Question 381: Ray Optics

Question

A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in such a way that its enf closer to the pole is 20 cm away from the mirror. The length of the image is

Accepted Answer

Image position of end A
$${1 \over {{v_A}}} + {1 \over { - 20}} = {1 \over { - 10}}$$
$$ \Rightarrow $$ v
A
= - 20 cm
Image position of the end B
$${1 \over {{v_B}}} + {1 \over { - 30}} = {1 \over { - 10}}$$
$$ \Rightarrow $$ v
B
= -15 cm
Length of the image is
L
A'B'
= |v
A
| - |v
B
| = 20 - 15 = 5 cm

Answer

10 cm

Answer

15 cm

Answer

2.5 cm

Answer

5 cm

Ray Optics

A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in such a way that its enf closer to the pole is 20 cm away from the mirror. The length of the image is

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