WAEC - Physics (2024 - No. 33)
The inside portion of a hollow metal sphere of diameter 20 cm is polished. The portion will therefore form a
Concave mirror of focal length 5cm.
Concave mirror of focal length 10 cm.
Convex mirror of focal length 10 cm
Convex mirror of focal length 5cm
Giải thích
Diameter = 20cm
The radius of curvature, R = 10cm
But, focal length, f = \(\frac{R}{2} = \frac{10}{2}\) = 5 cm.
When the inside portion of a hollow metal is polished, the outside is the reflecting surface. This forms a convex mirror.