What happens when convex lens of refractive index 1.2 is immersed in liquid of refractive index of 1.3. It's focal length remains same It behaves as concave lens It behaves as converging lens No changes take place. How will a ray of light travel if refractive index of lens and outside are same? It will bend towards normal It will bend away from normal It travels in straight path None of these. Two lens of power +10D and -10D are placed in cintact with each other. What will be the combined power and focal length. The power will be zero and focal length also zero The power will be zero and focal length infinity The power will be infinity and focal length zero Ther won't be any change. Every lens has two focal length. Under what condition are these two focal length not equal? When medium on both sides are same When medium on both side are different When light travels from rarer to denser When light travels from denser to rarer. A convex lens forms virtual image where is the object? At focal point beyond radius of curvature between focal point and optic centre At radius of curvature. A glass is immersed in water will its power change? Power will increase Power will decrease Power does not change The question is not correct. Sun glasses have curved surfaces, yet their power is zero. Why? The radius of curvature on both sides are different The radius of curvature on both side are same It is not possible to have zero power none of these. What type of lens is an air bubble inside water? A bi-concave lens A plano convex lens A bi-convex lens A plano concave lens. A convex lens has focal length 25cm. What will be its power? -2D +2D -4D +4D. Refractive index of a plano convex lens is 1.5. If its radius of curvature for curved side is 20 cm then its focal length will be? 80cm 60cm 40cm 20cm.