Question

To get three images of a single object one should have two plane mirrors at

• A. $30°$
• B. $60°$
• C. $90°$
• D. $120°$

Answer 1

The correct option is C

$90°$

Step 1: Given information

Number of images, $\mathrm{n}=3$

Let,

The number of images formed of two plane mirrors is placed at an angle $\mathrm{\theta }$be:

$\mathrm{n}=\frac{360°}{\mathrm{\theta }}-1$

Step 2: Calculation

By substituting the values in the above expression, we get

$$\begin{gathered} \Rightarrow 3=\frac{360°}{\mathrm{\theta }}-1 \\ \Rightarrow \mathrm{\theta }=\frac{360°}{4} \\ \Rightarrow =90° \end{gathered}$$

Therefore, to get three images of a single object one should have two plane mirrors at $90°$ that is option C.