Question

A wire is bent in the shape of a right-angled triangle and is placed in front of a concave mirror of focal length f, as shown in the figure. Which of the figures shown in the four options qualitatively represent(s) the shape of the image of the bent wire? (These figures are not to scale.)?

• A.
  
• B.
  
• C.
  
• D.
  

Answer 1

Distance of point A is f/2

Ref image .1

Let A’ is the image of A from mirror, for this image

$\frac{1}{v}+\frac{1}{-f/2}=\frac{1}{-f}$

$\frac{1}{v}=\frac{2}{f}-\frac{1}{f}=\frac{1}{f}$

Ref image .2

Image of line AB should be perpendicular to the principle axis & image of F will form at infinity, therefore correct image diagram is

Ref image.3

$\frac{f}{f-u}=\frac{h_2}{h_1}$

$h_2=\frac{-f(f-x)}{-f+x}$

$h_2=f$.