If a balloon is placed on an Erlenmeyer flask on a hot plate, what would happen to the balloon

Explain why the aperture of the spherical mirror should be small compared to the radius of curvature of the mirror.

Light traveling in a medium with a refractive index 1.19 is incident on a plate of another medium with index of refraction 1.79. at what angle of incidence is the reflected light fully polarized?

Acoil suspended freely, points in some direction when no current is passed through it . can you tell what will happen when a current is passed though it?