about lights?

Question

Imagine you are lost in the wilderness and need a campfire to cook your food. Would it be better to have a convex or concave mirror to start a fire using sunlight? Where would you position the mirror relative to some dry leaves in order that they would catch fire?

Answer 1

If I had a mirror, I would want it to be concave.

Place the leaves at the focal length from the surface, where the rays of light converge.