Coloration that is produced by the interference of light is referred to as $textbf{iridescence}$. Iridescence is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes.

Coloration that is produced by the interference of light is referred to as $textbf{iridescence}$. Iridescence is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes.

If the slit spacing on a diffraction grating is increased which means a grating with less lines per centimeters, the grating spread the colors of the light through a $textbf{smaller angle}$. This occurs because a small value of slit spacing and a large value of angle, $theta$ , have the same effect as a large slit spacing and a small angle.

If the slit spacing on a diffraction grating is increased which means a grating with less lines per centimeters, the grating spread the colors of the light through a $textbf{smaller angle}$.

If the wavelength is increased in a diffraction grating, the angle to the first principal maximum will also $textbf{increase}$. From the constructive interference by a diffraction grating expression, the wavelength is directly proportional to the angle.

If the wavelength is increased in a diffraction grating, the angle to the first principal maximum will also $textbf{increase}$. From the constructive interference by a diffraction grating expression, the wavelength is directly proportional to the angle.

$textbf{Given values:}$

$$
begin{align*}
m &= 1 \
theta &= 1.25 text{textdegree} \
lambda &= 587.5 text{ nm}
end{align*}
$$

The split spacing for the diffraction grating to the first order principal maximum of the yellow light from a helium discharge tube can be obtain by applying the expression for constructive interference by a diffraction grating :

$$
begin{align*}
d sin theta &= m lambda \
d &= dfrac{m lambda}{sin theta} \
&= dfrac{1 (587.5 cdot 10^{-9} text{ m})}{sin 1.25 text{textdegree}}
end{align*}
$$

$$
{boxed{d = 26.93 ~ mu text{m}}}
$$

$$
{d = 26.93 ~ mu text{m}}
$$

$textbf{Given values:}$

$$
begin{align*}
m &= 2 \
d &= 1.92 cdot 10^{-6} text{ m} \
lambda &= 692 text{ nm}
end{align*}
$$

The angle to the second order principal maximum of a light on a diffraction grating can be obtain by applying the expression for constructive interference by a diffraction grating :

$$
begin{align*}
d sin theta &= m lambda \
sin theta &= dfrac{m lambda}{d} \
theta &= {sin}^{-1} left( dfrac{m lambda}{d} right) \
&= {sin}^{-1} left( dfrac{2 (692 cdot 10^{-9} text{ m})}{1.92 cdot 10^{-6} text{ m}} right)
end{align*}
$$

$$
{boxed{theta = 46.12 text{textdegree}}}
$$

$$
{theta = 46.12 text{textdegree}}
$$

$textbf{Given values:}$

$$
begin{align*}
m &= 1 \
d &= 2.2 ~ mu text{m} \
theta &= 21 text{textdegree}
end{align*}
$$

The wavelength of the light that shines on a diffraction grating through an angle to the first order principal maximum can be obtain by applying the expression for constructive interference by a diffraction grating :

$$
begin{align*}
d sin theta &= m lambda \
lambda &= dfrac{d sin theta}{m} \
&= dfrac{2.2 cdot 10^{-6} text{ m} (sin 21 text{textdegree})}{1}
end{align*}
$$

$$
{boxed{lambda = 788.41 text{ nm}}}
$$