Question

The number of images formed by two
plane mirrors inclined at 60° of an object
placed symmetrically between mirror is?
(A) 6
(B) 7
(C) 5
(D) Infinite​

Answer 1

Given :

▪ Angle b/w two plane mirrors = 60°

To Find :

▪ The number of images formed by two plane mirrors.

Concept :

→ When two plane mirrors are inclined at an angle Φ and an object is placed b/w them, the number of images of an object are formed due to multiple reflections.

⚾ Condition-1 :

$\bigstar\:\underline{\boxed{\bf{\red{n=\dfrac{360\degree}{\theta}=even}}}}$

☞ Number of images = (n - 1)

⚾ Condition-2 :

$\bigstar\:\underline{\boxed{\bf{\blue{n=\dfrac{360\degree}{\theta}=odd}}}}$

☞ Number of images = (n - 1)

(For symmetric position of object)

☞ Number of images = n

(For asymmetric position of object)

Calculation :

$\dashrightarrow\sf\:n=\dfrac{360\degree}{\theta}\\ \\ \dashrightarrow\sf\:n=\dfrac{360\degree}{60\degree}\\ \\ \dashrightarrow\sf\:n=6\:(even)\\ \\ \dashrightarrow\sf\:Number\:of\:images=n-1\\ \\ \dashrightarrow\underline{\boxed{\bf{\orange{Number\:of\:Images=5}}}}\:\gray{\bigstar}$