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Question

Physics Question on Ray optics and optical instruments

A wire is bent in the shape of a right angled triangle and is placed in front of a concave mirror of focal length ff, 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

Explanation

Solution

Distance of point A is f/2
Let A' is the image of A from mirror, for this image
1v+1f2=1f\frac{1}{v} + \frac{1}{-\frac{f}{2}} = \frac{1}{-f}
1v=2f1f=1f\frac{1}{v} = \frac{2}{f} - \frac{1}{f} = \frac{1}{f}
ffu=h2h1\frac{f}{f-u} = \frac{h_{2}}{h_{1}}
h2=f(fx)f+xh_{2} = \frac{-f\left(f-x\right)}{-f+x}
h2=fh_{2} = f