10th Light

The radius of curvature of a convex lens is 20cm. What is its focal length?

• 10 cm

• 20 cm

• 30 cm

• 40 cm

Name the type of mirrors used in the following situations:

(i) Used by Dentist.

(ii) Rear-view mirror of vehicle

• (i) Diverging mirror

  (ii) Converging mirror

• (i) & (ii) Both Converging mirror

• (i) Converging mirror

  (ii) Diverging mirror

• (i) & (ii) Both Diverging mirror.

In the given ray diagram, which of the following path of the refracted ray is correct?

• 
• 
• 
• 

An object is kept at a distance of 4m in front of a spherical mirror, which forms its erect image at a distance of 1m

from the mirror. What is the magnification? Is the mirror concave or convex?

• m = +4

  Concave Mirror

• m = -4

  Convex mirror

• m = - 1/4

  Convex Mirror

• m = +1/4

  Convex Mirror

A concave mirror produces a three times magnified image on a screen. If the object is placed 20cm in front of the mirror, What is the image distance?

• -20 cm

• -40cm

• -60 cm

• -10 cm

Calculate the power of a lens whose focal length is +40 cm. Also Identify the nature of the lens.

• P = +0.25 D

  Concave lens.

• P = +2.5 D

  Convex lens

• P = +0.25 D

  Concave lens

• P = +2.5 D

  Convex Lens

Complete the path of the refracted ray of the given incident light on the given convex lens.

• 
• 
• 
• 

The image of a candle flame placed at a distance of 30cm from a mirror is formed on a screen placed in front of the mirror at a distance of 60cm from its pole. What is the nature of the mirror? Find its focal length.

• F = - 20 cm

  Concave Mirror

  Real & Inverted Image

• F = + 20 cm

  Concave Mirror

  Virtual & Erect Image

• F = - 20 cm

  Convex Mirror

  Real & Inverted Image

• F = + 20 cm

  Convex Mirror

  Virtual & Erect Image

A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top.

• Plane, convex and concave

• Convex, concave and plane

• Concave, plane and convex

• Convex, plane and concave

The refractive indices of glass and water with respect to air are 3/2 and 4/3 respectively. If the speed of light in glass is 2 x 10⁸ m/s, find the speed of light in water.

• 0.5 x 10⁸ m/s

• 3 x 10⁸ m/s

• 2.25 x 10⁸ m/s

• 2 x 10⁸ m/s