A spherical mirror and a thin spherical lens both have a focal length of -10 cm. The mirror and the lens are likely to be-

Question

Question

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RRB JE CBT I - (Held On: 30 May 2019 Shift 1)

Answer 1

The correct answer is both concave

Key Points

The focal length of a mirror or lens can be positive or negative, indicating whether it is converging or diverging.
A negative focal length indicates that both the spherical mirror and the thin spherical lens are diverging in nature.
For mirrors, a concave mirror has a positive focal length, and a convex mirror has a negative focal length.
For lenses, a convex lens has a positive focal length, and a concave lens has a negative focal length.
Thus, both the spherical mirror and the thin spherical lens having a focal length of -10 cm indicates that they are both concave in nature.

Additional Information

A concave mirror is also known as a converging mirror because it converges the light rays that fall on it.
A concave lens is also known as a diverging lens because it diverges the light rays passing through it.
The properties of concave mirrors and lenses make them useful in various applications such as telescopes, microscopes, and corrective lenses for myopia.
Understanding the sign convention in optics is crucial for correctly identifying the nature of mirrors and lenses.