Q63PP - University Physics with Modern Physics

Question

Next, unpolarised light is reflected off a smooth horizontal piece of glass, and the reflected light shines on the insect. Which statement is true about the two types of cells? (a) When the light is directly above the glass, only type V detects the reflected light. (b) When the light is directly above the glass, only type H detects the reflected light. (c) When the light is about 35° above the horizontal, type V responds much more strongly than type H does. (d) When the light is about 35° above the horizontal, type H responds much more strongly than type V does.

Step-by-Step Solution

Answer

The correct answer is option (d) when the light is about 35° above the horizontal, type H responds much more strongly than type V does.

Step1: Calculating the values of the polarised angle

The light could be polarized by total reflection. This is Brewster’s law, which states that if the incident angle equals to the polarized angle, the light will be polarized. Brewster’s law is in the form:

$\tan {\theta }_p=\frac{n_b}{n_a}$

Step 2: Calculating the value

Now to calculate the value of the polarized angle \theta

$$\begin{gathered} {\theta }_p={\tan }^{-1}\frac{n_b}{n_a} \\ ={\tan }^{-1}\frac{1.5}{1} \\ =56.30 \end{gathered}$$

The glass is horizontal hence the incident light will be:

$$\begin{gathered} {\theta }_a=90-35 \\ =55 \end{gathered}$$

The angle is close to the polarized angle hence the correct answer is option.