Question

A girl was playing with a thin beam of light from her laser torch by directing it from different directions on a convex lens held vertically. She was surprised to c that in a particular direction the beam of light continues to move along the same direction after passing through the lens. Of white light is used with (i)parallel (ii)non parallel sides

Answer 1

she would have passed the light through the optical centre



It means the beam of light is passing  through optical centre of lens. A beam of light that passes through the optical centre of convex lens continues to move along the same direction after passing through the lens, since the light beam travels at angle of 900 from the plane of the surface do not bend. 

Answer 2

Explanation:

hope this helps u guys