Test 3: Ch. 31-34 – Flashcards
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Ch. 31 Q. 1 An ac source of period T and maximum voltage V is connected to a single unknown ideal element that is either a resistor, and inductor, or a capacitor. At time t = 0 the voltage is zero. At time t = T/4 the current in the unknown element is equal to zero, and at time t = T/2 the current is I = -Imax, where Imax is the current amplitude. What is the unknown element?
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A capacitor
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Ch. 31 Q. 2 When an LRC series circuit is at resonance, which one of the following statements about that circuit is accurate? (There may be more than one correct choice.)
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The current amplitude is a maximum.
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Ch. 31 Q. 3 In a series LRC circuit, the frequency at which the circuit is at resonance is f0. If you double the resistance, the inductance, the capacitance, and the voltage amplitude of the ac source, what is the new resonance frequency?
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f0/2
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Ch. 31 Q. 4 Which one of the phasor diagrams shown below best represents a series LRC circuit driven at resonance?
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3
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Ch. 31 Q. 6 A resistor is connected to an ideal ac power supply. The current in the resistor
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is in phase with the voltage across the resistor.
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Ch. 31 Q. 7 A resistor is connected to an ideal ac power supply. How does the average power dissipated in the resistor change as the frequency in the ac power supply decreases?
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It does not change.
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Ch. 31 Q. 8 When an LRC series circuit is driven at resonance, which of the following statements about the circuit is correct?
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The inductive reactance and the capacitive reactance are exactly equal to each other.
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Ch. 31 Q. 9 The primary coil of a transformer has 100 turns and its secondary coil has 400 turns. If the ac voltage applied to the primary coil is 120 V, what voltage is present in its secondary coil?
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480 V
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Ch. 31 Q. 10 The plate on the back of a certain computer scanner says that the unit draws 0.34 A of current from a 120 V, 60 Hz line. Find the root mean square current:
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0.34 A
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Ch. 31 Q. 11 The plate on the back of a certain computer scanner says that the unit draws 0.34 A of current from a 120 V, 60 Hz line. Find the current amplitude:
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0.48 A
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Ch. 31 Q. 12 The plate on the back of a certain computer scanner says that the unit draws 0.34 A of current from a 120 V, 60 Hz line. Find the average current:
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????
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Ch. 31 Q. 13 A capacitor C and an inductance L are operated at the same angular frequency. If L = 5.00 mH and C = 3.50 micro Farad, what is the numerical value of the angular frequency?
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7560 Rad/sec
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Ch. 31 Q. 14 A capacitor C and an inductance L are operated at the same angular frequency. If L = 5.00 mH and C = 3.50 micro Farad, what is the reactance of each element?
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37.8 Ohm
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Ch. 31 Q. 15 What is the reactance of a 3.00 - H inductor at a frequency of 80.0 Hz?
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1510 Ohm
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Ch. 31 Q. 16 What is the inductance of an inductor whose reactance is 120 Ohm at 80.0 Hz?
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0.239 H
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Ch. 31 Q. 17 What is the reactance of a 4.00 micro F capacitor at a frequency of 80.0 Hz?
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497 Ohm
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Ch. 31 Q. 18 What is the impedance of the circuit?
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224 Ohm
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Ch. 31 Q. 19 What is the current amplitude?
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0.134 A
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Ch. 31 Q. 20 What are the voltage amplitudes across the resistor and across the inductor?
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26.8 V; 13.4 V
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Ch. 31 Q. 21 A transformer is needed to step down a high-voltage, low-current input to a low-voltage, high-current output. The secondary voltage must not exceed 670 volts and the primary current must not exceed 0.11 amperes. If the power is to be 900 watts, what is the smallest possible ratio of turns (primary to secondary) in the transformer?
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12
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Ch. 31 Q. 22 An L-R-C series circuit is connected to a 120 - Hz ac source that has root mean square voltage = 80.0 V. The circuit has a resistance of 75.0 ohm and impedance at this frequency of 105 Ohm. What average power is delivered to the circuit by this source?
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43.5 W
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Ch. 31 Q. 23 The power of a certain CD player operating at 120 V rms is 20.0 W. Assuming that CD player behaves like a pure resistance, find the maximum instantaneous power.
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40 W
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Ch. 31 Q. 24 The power of a certain CD player operating at 120 V rms is 20.0 W. Assuming that CD player behaves like a pure resistance, find the rms current.
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0.167 A
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Ch. 31 Q. 25 The power of a certain CD player operating at 120 V rms is 20.0 W. Assuming that CD player behaves like a pure resistance, find the resistance of this player.
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720 Ohm
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Ch. 31 Q. 26 What could you do to operate your blower via the 240 - V line in Europe?
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Use step down transfermer with N1 = 2N2
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Ch. 31 Q. 27 What current will your blower draw from an European outlet?
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6.67 A
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Ch. 31 Q. 28 What resistance will your blower appear to have when operated at 240 V?
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36 Ohm
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Ch. 31 Q. 29 What is the power factor for this circuit?
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0.697
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Ch. 31 Q. 30 What is the impedance of this circuit?
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344
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Ch. 31 Q. 31 What is the rms voltage of the source?
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155 V
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Ch. 31 Q. 32 What Average power is delivered by the source?
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48.6 W
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Ch. 31 Q. 33 What is the average rate at which electrical energy is converted into thermal energy in the resistor?
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48.6
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Ch. 31 Q. 34 What is the average rate at which electrical energy is dissipated in capacitor?
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Zero
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Ch. 31 Q. 35 You have a 200 Ohm resistor, a 0.400 H inductor, a 5.00 micro C capacitor, and a variable-frequency ac source with an amplitude of 3.00 V. You connect all four elements together to form a series circuit. (a) At what frequency will the current in the circuit be greatest? (b)...What will be the current amplitude at this frequency?(c) What will be the current amplitude at an angular frequency of 400 rad/sec?At this frequency will the source voltage lead or lag the current?
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(a)707.0 Rad/Sec; (b) 0.015A (c) .0076A
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Ch. 32 Q. 1 A capacitor is hooked up to a resistor and an AC voltage source as shown in the figure. The output of the source is given by V(t) = V0 sin ωt. The plates of the capacitor are disks of radius R. Point P is directly between the two plates, equidistant from them and a distance R/2 from the center axis. At point P
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there is a time-varying magnetic field.
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Ch. 32 Q. 2 Which one of the following lists is a correct representation of electromagnetic waves from longer wavelength to shorter wavelength?
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radio waves, microwaves, infrared, visible, UV, X-rays, gamma rays
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Ch. 32 Q. 3 In an electromagnetic wave, the electric and magnetic fields are oriented such that they are
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perpendicular to one another and perpendicular to the direction of wave propagation
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Ch. 32 Q. 4 If the magnetic field of an electromagnetic wave is in the +x-direction and the electric field of the wave is in the +y-direction, the wave is traveling in the
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-z - direction
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Ch. 32 Q. 5 An electromagnetic wave is propagating towards the west. At a certain moment the direction of the magnetic field vector associated with this wave points vertically up. The direction of the electric field vector of this wave is
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horizontal and pointing south
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Ch. 32 Q. 6 An electromagnetic wave propagates along the +y direction as shown in the figure. If the electric field at the origin is along the +z direction, what is the direction of the magnetic field?
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+x
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Ch. 32 Q. 7 The energy per unit volume in an electromagnetic wave is
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equally divided between the electric and magnetic fields
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Ch. 32 Q. 8 If an electromagnetic wave has components Ey = E0 sin(kx - ωt) and Bz = B0 sin(kx - ωt) , in what direction is it traveling?
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+x
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Ch. 32 Q. 9 When an electromagnetic wave falls on a white, perfectly reflecting surface, it exerts a force F on that surface. If the surface is now painted a perfectly absorbing black, what will be the force that the same wave will exert on the surface?
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F/2
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Ch. 32 Q. 10 Given that the wavelengths of visible light range from 400 nm to 700 nm, what is the highest frequency of visible light? (c = 3.0 x 108 m/s)
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7.5 × 10^14 Hz
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Ch. 32 Q. 11 The magnitude of the electric field at a point P for a certain electromagnetic wave is 570 N/C. What is the magnitude of the magnetic field for that wave at P? (c = 3.0 x 108 m/s)
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1.90 µT
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Ch. 32 Q. 12 The magnitude of the magnetic field at point P for a certain electromagnetic wave is 2.12 μT. What is the magnitude of the electric field for that wave at P? (c = 3.0 x 108 m/s)
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636 N/C
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Ch. 32 Q. 13 If the electric field and magnetic field of an electromagnetic wave are given by E = E0 sin(kx - ωt) and B = B0 sin(kx - ωt), and if the value of E0 is 51 µV/m, what is the value of B0? (c = 3.0 x 108 m/s)
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1.7 × 10^-13 T
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Ch. 32 Q. 14 A planar electromagnetic wave is propagating in the +x direction. At a certain point P and at a given instant, the electric field of the wave is given by = (0.082 V/m) . What is the magnetic vector of the wave at the point P at that instant? (c = 3.0 x 108 m/s)
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0.27 nT in k direction
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Ch. 32 Q. 15 A sinusoidal electromagnetic wave is propagating in vacuum. (a) At a given point and at a particular time the electric field is in the +x-direction and the magnetic field is in the -y-direction. What is the direction of propagation of the wave? (b) At the above point the intensity of the wave is What is the electric field amplitude at this point?
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(a) -z-direction (b) 25 V/m
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Ch. 32 Q. 16 If the intensity of an electromagnetic wave is 80 MW/m2, what is the amplitude of the magnetic field of this wave? (c = 3.0 x 108 m/s, μ0 = 4π × 10-7 T ∙ m/A, ε0 = 8.85 × 10-12 C2/N ∙ m2)
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0.82 mT
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Ch. 32 Q. 17 A source of light produces electric field amplitude of 9.10 V/m, 44 m from the source. What is the power output from the source?
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2672 W
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Ch. 32 Q. 18 If a beam of electromagnetic radiation has an intensity of 120 W/m2, what is the maximum value of the electric field? (c = 3.0 x 108 m/s, μ0 = 4π × 10-7 T ∙ m/A, ε0 = 8.85 × 10-12 C2/N ∙ m2)
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0.30 kV/m
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Ch. 32 Q. 19 An electromagnetic wave has a peak electric field of 3.0 kV/m. What is the intensity of the wave? (c = 3.0 x 108 m/s, μ0 = 4π × 10-7 T ∙ m/A, ε0 = 8.85 × 10-12 C2/N ∙ m2)
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12 kW/m^2
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Ch. 32 Q. 20 The magnetic field of an electromagnetic wave has a peak value of 5.0 × 10-10 T. What is the intensity of the wave? (c = 3.0 x 108 m/s, c = 3.00 × 108 m/s, μ0 = 4π × 10-7 T ∙ m/A, ε0 = 8.85 × 10-12 C2/N ∙ m2)
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3.0 × 10^-5 W/m^2
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Ch. 32 Q. 21 An electromagnetic wave has a wavelength of 2.90 × 10-5 m in air and a wavelength of in a certain dielectric material. Find the dielectric constant for the material.
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2.78
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Ch. 32 Q. 22 The electric field amplitude near a certain radio transmeter is 3.85 × 10-3 V/m. What is the amplitude of the magnetic field?
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1.28 × 10^-11
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Ch. 33 Q. 1 A ray of light is incident on a plane surface separating two sheets of glass with refractive indexes 1.70 and 1.58. The angle of incidence is 62.0° and the ray originates in the glass with n = 1.70. Compute the angle of refraction.
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71.8°
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Ch. 33 Q. 2 Unpolarized light is incident upon two polarization filters that do not have their transmission axes aligned. If 18% of the light passes through this combination of filters, what is the angle between the transmission axes of the filters?
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53°
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Ch. 33 Q. 3 Unpolarized light passes through three polarizing filters. The first one is oriented with a horizontal transmission axis, the second filter has its transmission axis 25.7° from the horizontal, and the third one has a vertical transmission axis. What percent of the light gets through this combination of filters?
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7.6%
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Ch. 33 Q. 4 Sunlight reflects off the smooth surface of a swimming pool. (a) For what angle of reflection is the reflected light completely polarized? (b) What is the corresponding angle of refraction?
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(a) 53.1° (b) 36.9°
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Ch. 33 Q. 5 An oil layer that is 5.0 cm thick is spread smoothly and evenly over the surface of water on a windless day. What is the angle of refraction in the water for a ray of light that has an angle of incidence of 45° as it enters the oil from the air above? (The index of refraction for the oil is 1.15, and for water it is 1.33.)
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32°
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Ch. 33 Q. 6 The speed of light in a material is 0.50 c. What is the critical angle of a light ray at the interface between the material and a vacuum?
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30°
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Ch. 33 Q.7 What is the critical angle for light traveling from crown glass (n = 1.52) into water (n = 1.33)?
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61°
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Ch. 33 Q. 8 The critical angle in air for a particular type of glass is 39.0°. What is the speed of light in this class glass? (c = 3.00 × 10∧8 m/s)
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1.89 × 10^8 m/s
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Ch. 33 Q. 9 In the figure, the orientation of the transmission axis for each of three polarizing sheets is labeled relative to the vertical direction. A beam of light, polarized in the vertical direction, is incident on the first polarized with an intensity of 1000 W/m2. What is the intensity of the beam after it has passed through the three polarizing sheets when θ1 = 30°, θ2 = 30° and θ3 =60°?
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563 W/m^2
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Ch. 33 Q. 10 In Fig. 33.7, a ray of light in air is incident on a flat piece of glass, at an angle of φo = 62° with respect to the normal. The glass has an index of refraction What is the angle θ between the reflected (ray b) and refracted (ray c) rays?
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82°
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Ch. 33 Q. 11 A ray of light traveling in air makes a 63.0° angle with respect to the normal of the surface of a liquid. It travels in the liquid at a 43.8° angle with respect to the normal. Find the critical angle for total internal reflection. (Assume n=1 for air.)
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51.0°
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Ch. 33 Q. 12 When unpolarized light from air (n = 1) is incident on a piece of glass with index of refraction the reflected light is found to be completely polarized when the angle of incidence is θB. What is the angle of refraction in this case? Give a numerical answer.
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36.7°
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Ch. 33 Q. 13 Three linear polarizers are oriented as follows: The axis of the second is at an angle of 59.0° relative to the first. The axis of the third is at an angle of 31.0° relative to the second, so the axis of the third polarizer is perpendicular to the axis of the first. Unpolarized light of intensity Io= 60.7 W/m^2 is incident on the first polarizer. (a) What is the intensity of the light after it passes through all three polarizers? (b) What is the intensity of the transmitted light if the second polarizer is removed?
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(a) 5.91 W/m2 (b) 0
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Ch. 33 Q. 14 Light of wavelength 475 nm in vacuum enters a plastic as shown in Fig. 33.9. Measurements of the light in the plastic indicate that its wavelength there is 394 nm. (a) What is the frequency of the light in the plastic? (b) At what direction does the light travel with respect to the normal in the plastic?
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(a) 6.32 × 1014 Hz (b) 22.9°
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Ch. 33 Q.15 A tank contains benzene, which has index of refraction 1.50. A dime is on the bottom of the tank. When viewed at normal incidence the dime appears to be 63 cm below the surface of the benzene. What is the actual depth of the benzene?
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95 cm
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Ch. 33 Q.16 A parallel beam of light in air makes an angle of 47.5° with the surface of a glass plate having an index of refraction n=1.66 (a) What is the angle between the reflected part of the beam and the surface of the glass? (b) What is the angle between the refracted beam and the surface of the glass?
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(a) 47.5°; (b) 66°
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Ch. 33 Q. 17 Light with frequency 5.80 × 1014 Hz travels in a block of glass that has an index of refraction of 1.52. What is the wavelength of the light (a) in vacuum and (b) in the glass?
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(a) 517 nm; (b) 340 nm
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Ch. 33 Q. 18 Light traveling in air is incident on the surface of a block of plastic at an angle of 62.7° to the normal and is bent so that it makes a 48.1° angle with the normal in the plastic. Find the sped of light in the plastic.
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2.51 × 10^8 m/s
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Ch. 33 Q. 19 A ray of light is traveling in a glass cube that is totally immersed in water. You find that if the ray is incident on the glass - water interface at an angle to the normal larger that 48.7° , no light is refracted into the water. What is the refractive index of the glass?
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1.77
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Ch. 33 Q. 20 A parallel ray of unpolarized light in air is incident at an angle of 54.5° (with respect to the normal) on a plane glass surface. The reflected beam is completely linearly polarized. (a) What is the refractive index of the glass? (b) What is the angle of refraction of the tranmitted beam?
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(a) 1.40; (b) 35.5°
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Chpt 34 Q1 A convex lens has focal length f. If an object is LOCATED EXTREMELY FAR FROM THE LENS (INFINITY), the image formed is located what distance from the lens? (the visual was on chegg, not in the quiz, but it helps)
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f
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Chpt 34 Q2 A convex lens has a focal length f. An object is placed at a distance BETWEEN F AND 2F on a line perpendicular to the center of the lens. The image formed is located at what distance from the lens?
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farther than 2f
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Chpt 34 Q3 A convex lens has a focal length f. An object is placed BETWEEN INFINITY AND 2F from the lens along a line perpendicular to the center of the lens. The image is located at what distance from the lens?
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between f and 2f (The focal length (f) is the distance from the lens that parallel light rays entering the lens will come together, or converge, at the same point. So an object very distant from the lens (whose light rays are essentially parallel) will produce an image at a distance f from the lens. As the object comes closer, the distance of the image will increase according to the formula: 1/do + 1/di = 1/f, where do is the distance of the object and di is the distance of the image. When the object is at a distance 2f, the image will also be at distance 2f on the other side of the lens. So when the object is between 2f and an infinite distance away, the image will be between f and 2f)
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Chpt 34 Q4 What is the size of the smallest vertical mirror in which a woman of height "h" can see her full-length image?
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h/2 (Since Incidence = Reflection and assuming you're standing perfectly straight, the vertical distance traveled before the light hits the mirror must be the same as the vertical distance traveled after it hits the wall. Thus, it must bounce right in the half way point between the floor and the top of your head. thus, mirror = h/2)
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Chpt 34. Q5 If you run away from a plane mirror at 2.40 m/s, at what speed does your image move away from you?
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2.4 m/s Speed of the man u = 2.4 m / s Speed of the image of the mirror v = 2.4 m / s So, speed of the image with respect to you = v + u = 4.8 m / s, then divide by 2, so the answer is 2.4 m/s
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Chpt 34. Q6 A object is 12 cm in front of a concave spherical mirror, and the image is 3.0 cm in front of the mirror. What is the focal length of the mirror?
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2.4 cm For a mirror 1/f = 1/v + 1/u here u = 12 cm ; v = 3 cm 1/f = 1/3+ 1/12 1/f = 5/12 f=12/5 cm=2.4 cm
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Chpt 34. Q7 A concave spherical mirror with a radius of 20 cm creates a real image 30 cm from the mirror. How far is the object from the mirror?
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15cm Radius of curvature R =20 cm focal length f = R / 2 = 10 cm distance of the image v = 30 cm we know ( 1/ u ) + (1/ v ) = ( 1/ f ) ( 1/ u ) = ( 1/ 10 ) - ( 1/ 30 ) = 0.0666666 from this distanc eof the object u = 15cm
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Chpt 34 Q8 The spherical side mirror on a car is convex and has a radius of curvature of 25 cm. Another car is following, 20 m behind the mirror. If the height of the car is 1.6 m, how tall is its image?
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0.99cm
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Chpt 34 Q9 A man's face is 30 cm in front of a concave spherical shaving mirror. If the image is erect and 1.5 times as large as his face, what is the radius of curvature of the mirror?
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180 cm follow workout attached to question, but then find radius of curvature: 2f, so 2x90 = 180 cm
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Chpt 34 Q10 A swimming pool is filled to a depth of 2.0 m. How deep does the pool appear to be from above the water, which has an index of refraction of 1.33?
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Apparent depth = Real depth/Refractive index of water 2/1.33 =1.504 m
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Chpt 34 Q11 A fish appears to be 2.00 m below the surface of a pond when viewed almost directly above by a fisherman. What is the actual depth of the fish? (nwater = 1.33)
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The refractive index= real depth/ apparent depth real depth = refractive index * apparent depth = 1.33 * 2 = 2.66 m
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Chpt 34 Q12 A thin converging lens is found to form an image of a distant building 24 cm from the lens. If an insect is now placed 16 cm from this lens, how far FROM THE INSECT will its image be formed?
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32 cm
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Chpt 34 Q13 It is desired to project the image of an object four times its actual size using a lens of focal length 20 cm. How far from the lens should the object be placed?
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25cm m = v/u v = -4u 1/20 = -1/4u - 1/u 1/20 = -5/4u u = -25 cm note that here image formed is virtual so you need to put m = -4
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Chpt 34 Q14 When an object is placed 166 cm from a diverging thin lens, its image is found to be 83 cm from the lens. The lens is removed, and replaced by a thin converging lens whose focal length is the same in absolute value as the diverging lens. This second lens is at the original position of the first lens. Where is the image of the object now?
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at Infinity (This is the workout, but with different numbers. I tried to replace with ours, but not sure how to get f correctly.) Given object distance = u = 118cm, image distance = v = 59cm. Hence the focal length is given by (1/f) = (1/v) + (1/u) = -0.01695 + 0.00848 (v is -ve since for concave lens, image is towards the object distance and hence from sign convention due to curvature, it will be -ve) = -0.00848 Hence f = -118 cm. (-ve sign implies that this is a concave lens). Now given a thin lens(convex) with same magnitude of focal length = f = 118.1cm is replaced here. The object distance is again the same. Hence by substituting the values in the formula (1/f) = (1/v) + (1/u) 0.00848 = (1/v) + 0.00848 (Here focal length, object and image distances will be +ve since its a convex lens). Hence (1/v) = 0 => v = infinity (which should be when an object is placed at a distance of focal length of the lens, its image will be at infinity).
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Chpt 34 Q15 An object 3.4 mm tall is placed 25 cm from the vertex of a convex spherical mirror. The radius of curvature of the mirror has magnitude 28 cm. (a) How far is the image from the vertex of the mirror? (b) What is the height of the image?
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a) 9 cm b) 1.2 mm
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Chpt 34 Q16 In Fig. 34.6, an object of height 2.00 mm is placed 35 cm to the left of a converging lens of focal length A diverging lens of focal length is 15 cm to the right of the first lens. Calculate the (a) location (relative to the second lens), (b) nature (real or virtual), (c) orientation (erect or inverted), and (d) height of the final image formed by the pair of lenses.
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15 cm to the left of the second lens (b) virtual (c) erect (d) 1.2 mm
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Chpt 34 Q17 A spherical, concave, shaving mirror has a radius of curvature of of 32.0 cm. (a) What is the magnification of a person's face when it is 12.0 cm to the left of the vertex of the mirror? (b) Where is the image? (c) Is the image real or virtual?
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(a) m =4; (b) v =-48 cm; (c) Virtual
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Chpt 34 Q18 The near point a certain hyperopic eye is 100 cm in front of the eye. To see clearly an object that is 25 cm in front of the eye, what contact lens is required?
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3 diopter, converging lens
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Chpt 34 Q19 The far point of a certain myopic eye is 50 cm in front of eye. to see clearly an object at infinity, what eyeglass lens is required? assume that the lens is worm 2 cm in front of the eye.
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-2.1 diopter, diverging lens -50cm+ 2cm = -48cm 1/-48 =-2.1 diopters
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Chpt 34 Q20 A concave mirror forms an image, on a wall 3.00 m from the mirror, of the filament of a headlight lamp 10.0 cm in front of the mirror. (a) What are the focal length and the radius of curvature of the mirror ? (b) What is the height of the image if the height of the object is 5.00 mm?
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(a) 97.0 cm; (b) -15 cm a) For all mirrors, we have the equation 1/f = 1/do + 1/di. In this case, do = 10e-2m = 0.1m, di = 3m. So 1/f = 1/0.1 + 1/3 = 10.33, f = 9.7cm. R = 2f = 19.4cm. b) Since hi/ho = di/do, hi = ho*di/do = 5e-3*3/0.1 = 0.15m.
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Chpt 34 Q21 A speck of dirt is embedded 3.50 cm below the surface of a sheet of ice with refractive index n = 1.309. What is its apparent depth?
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2.67 cm Use formula D(a) = D(r)/n Where D(a) = Apparent depth, D(r) = Real depth and n = refracting index of the medium. Now coming to your question here Dr is 3.5 and n is 1.309 so using formula Da = Dr/n Da = 3.5 / 1.309 = 2.67 So, Apparent depth will be 2.67 cm.
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Chpt 34 Q22 A fisherman in a stream 39 cm deep looks downward into the water and sees a rock on the stream bed. How deep does the stream appear to the fisherman? Assume that the index of refraction of the water is 1.33.
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29cm One needs to assume that the eyes are substantially above the water so that sin(theta) is approximately theta. ( small angle approximation). The point at which a ray leaving the fish hits the surface of the water is x to the side of the centreline and the depth of the water is d x/d = sin( angle of incidence) if the apparent depth of the water is h then x/h = sin( angle of refraction) and applying snells law 1 sin ( theta air) = 1.33 sin( theta water) 1 * x/h = 1.33 * x/d d/h = 1.33 or h/d = 1/1.33 h/30 = 1.33 h = 39 /1.33 = 29.33 cm so that is the apparent depth of the stream assuming:- 29 cm
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Chpt 34 Q23 In the figure, the thin lens forms a real image of the object 94.0 cm from the object. What is the focal length of the lens?
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22 cm The image distance is 94.0 - 35.0 = 59.0 cm . And then the focal length is . f = io / (i+o) = 59 * 35 / (59+ 35) = 22.0 cm
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Chpt 34 Q24 In the figure, the image is viewed on a screen and is 13.5 mm tall. What is the focal length of the lens?
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+20.4 h'/h=s'/s (s)(h'/h)=s' (35)(1.35/.97)=48.71=s' then use: (1/s)+(1/s')=(1/f) (1/35)+(1/48.71)=1/f =+20.4
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Chpt 34 Q25 An optical system comprises in turn, from left to right: an observer, a lens of focal length +30 cm, an erect object 20 mm high, and a convex mirror of radius 80 cm. The object is between the lens and the mirror, 20 cm from the lens and 50 cm from the mirror. The observer views the image that is formed first by reflection and then by refraction. What is the position of the final image, measured from the mirror?
answer
114 cm here the image is first formed by mirror: 1/s1 + 1/s1' = 1/f1 1/50 + 1/s1' = -1/40 s1' = -22.22 cm for lens: s2 = (20+50) + 22.22 s2 = 92.22 cm 1/s2 + 1/s2' = 1/f2 1/92.22 + 1/s2' = 1/30 s2' = 44.44 cm to the left of the lens position from the mirror = 44 + 70 = 114 cm
