A small bulb is placed at the focus of a concave mirror of focal length 12 cm. The reflected beam is
Aa parallel beam
Ba converging beam to 12 cm
Ca diverging beam
Dfocused at 24 cm
Answer & Solution
Correct answer: A. a parallel beam
Rays from an object at the focus reflect parallel to the principal axis — this is the principle of searchlights and headlamps.
Related questions
For a concave mirror, as an object moves from infinity towards the focus, the real imageThe power of a lens is −2.5 D. The lens isWhich mirror is used as a rear-view mirror in vehicles, and why?An object 4 cm tall is placed 15 cm from a convex lens of focal length 10 cm. The image heA ray of light travelling in air enters water (n = 4/3). It bendsThe laws of reflection hold good forA convex lens forms a real image three times the size of the object on a screen. If the foAn object is placed at the centre of curvature of a concave mirror. The image formed is