All Solutions
Page 553: Lesson Check
$$
C<A=B
$$
C<A=B
$$
$$
I_{f}=I_{i}costheta_{1}costheta_{2}=left(37.0 {rm W/m^{2}}right)left(cos45text{textdegree}right)left(cos45text{textdegree}right)=9.25
$$
In the case B, we have
$$
I_{f}=I_{i}costheta_{1}costheta_{2}=left(37.0 {rm W/m^{2}}right)left(cos45text{textdegree}right)left(cos45text{textdegree}right)=9.25
$$
In case C, we have
$$
I_{f}=I_{i}costheta_{1}costheta_{2}=left(37.0 {rm W/m^{2}}right)left(cos45text{textdegree}right)left(cos90text{textdegree}right)=0
$$
text{a)} I_{f} = 9.25
$$
$$
text{b)} I_{f} = 9.25
$$
$$
text{c)} I_{f} = 0
$$
Law of Malus :$I_f=I_i cos^2 theta$
we can the deduce the following:
$$
I_f=I_2 cos^2 theta_2=I_1 cos^2 theta_2*cos^2 theta_1= frac{1}{2} I_i cos^2 theta_2 cos^2 theta_1=
frac{1}{2} (25.5frac{W}{m^2}) cos^2 45*cos^2 45=3.2 frac{W}{m^2}
$$
$$
I_f=frac{1}{2} I_i cos^2 theta_2 cos^2 theta_1=
frac{1}{2} (25.5frac{W}{m^2}) cos^2 45*cos^2 0=6.4 frac{W}{m^2}
$$
tt{(a)$3.2 frac{W}{m^2}$,(b)$6.4 frac{W}{m^2}$}
$$