Which mirror type is used in solar furnaces to focus sunlight?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. Concave.
A Concave mirror is used in solar furnaces because of its unique converging property. When sunlight, which consists of parallel rays, strikes the curved surface of a large concave mirror, it is reflected and concentrated at a single point known as the principal focus. By placing a vessel or furnace at this focal point, the intense concentration of solar energy produces extremely high temperatures, often exceeding 3,000°C, which is ideal for melting metals or generating steam for power.
Other options:
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Convex: This mirror diverges light rays outward, spreading the energy over a larger area rather than concentrating it, which would make it useless for heating.
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Plane: A flat mirror reflects light at the same angle it hits, meaning it cannot focus rays to a single point to generate intense heat.
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Biconvex: This is a type of lens, not a mirror; while it can focus light through refraction, it is impractical and too expensive for large-scale solar furnaces compared to mirrors.