Correct Answer - Option 4 : 60 cm from the mirror
CONCEPT:
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Concave mirror: The mirror in which the rays converge after falling on it is known as the concave mirror.
- Concave mirrors are also known as a converging mirror.
- The focal length of a concave mirror is negative according to the sign convention.
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Magnification: In a concave mirror, the magnification is the ratio of the height of the image to the height of the object.
- When the image is real, the magnification will be negative because the real image is inverted.
- When the image is virtual, the magnification will be positive because the virtual image is erect.
\(m = \frac{-v}{u}\)
where m is magnificent, v is the distance of the image from the mirror, and u is the distance of the object from the mirror.
CALCULATION:
Given that u = -20 cm and m = -3.
\(m = \frac{-v}{u} \)
\(-3=\frac{-v}{-20}\)
v = -60 cm
So the correct answer is option 4.
