Question

How many images of an object will be formed when the object is placed between teo plane mirrors who are inclined at the following angles to one another?

• A. ${120}^0$
• B. ${45}^0$
• C. ${180}^0$
• D. ${60}^0$
• E. ${90}^0$

Answer 1

Answer: (D)

${60}^0$

$\begin{array}{c}\text{The formula to calculate the no of images of}\\ \text{an object placed between}2\text{plane mirrors.}\\ (\frac{360}{\theta }-1)\text{where}\theta \text{is angle b/w mirrors}\end{array}$

A) $\theta ={120}^{\circ }$

$n=\frac{360}{120}-1$

$=3-1=2$ images formed

B) $\begin{array}{cc}\theta & =45\\ n& =\frac{360}{45}-1\end{array}$

$=8-1=7$ images formed

c) $\theta ={180}^{\circ }$

$n=\frac{360}{180}-1$

$=2-1=1$ image formed

D) $\begin{array}{cc}\theta & ={60}^{\circ }\\ n& =\frac{360}{60}-1=6-1\end{array}$

$=5$ images formed

E) $\theta ={90}^{\circ }$

$n=\frac{360}{90}-1=4-1$

$=3$ images