Question

True or False :-
1: A convex mirror cannot form a real image.
2: A concave mirror is used in solar cookers.
3: The normals drawn at different points of a concave mirror will all pass through the centre of curvature.

Answer 1

1)true:this is because a convex mirror will have no real focal point since any light rays reflected off the mirror would diverge from one another. Try drawing a diagram with an arc for the convex mirror. Now, draw lines coming perpendicularly off any local point of the mirror, they will never cross. Hence, there is no focal point, and the image on the mirror will never be inverted/real in appearance.
2)true:To focus the Infra red rays from the Sun in a pot the concave mirror is used.The spot at which the rays converge obtains high flux and hence the heat is concentrated at that point. the same point has the absorbing pot positioned.Hence the solar thermal effect is felt and is used for cooking.
3)false