The principle on which mirror work is

• refraction

• polarization

• reflection

• total internal reflection

John's face is 20 cm in front of a concave shaving mirror. If he observes his image to be twice as big and upright. What is the focal length of the mirror?

• 10 cm

• 20 cm

• 30 cm

• 40 cm

• 50 cm

A converging lens with focal length of 12 cm produces a 3 cm high virtual image of a 1cm tall object. Which entry is correct?

• Image Distance Image Location 8cm same side of lens as object

• Image Distance Image Location

  8 cm opposite side of lens from object

• Image Distance Image Location

  12 cm opposite side of lens from object

• Image Distance Image Location

  24 cm opposite side of lens from object

• Image Distance Image Location

  24 cm same side of lens from object

Describe fully the image of an object which is 10 cm high and 28 cm from a diverging lens of focal length -7.0 cm.

• virtual, upright, smaller, 5.6 cm in front of lens, 2.0 cm high

• virtual, inverted, smaller, 9.3 cm in front of lens, 3.3 cm high

• virtual,upright, larger, 5.6 cm in front of lens, 20.0 cm high

• real, inverted, smaller, 5.6 cm in front of lens, 2.0 cm high

If you wish to take a picture of your image while standing 5 m in front of a plane mirror, for what distance should you set your camera to provide sharpest focus?

• 10 m

• 5 m

• 2 m

• 2.5 m

A convex spherical mirror has a focal length of -20 cm. An object is placed 10 cm in front of the mirror on the mirror's axis. Where is the image located?

• 20 cm behind the mirror

• 6.7 cm in front of the mirror

• 6.7 cm behind the mirror

• 20 cm in front of the mirror

The bending of light as it moves from one medium to another with differing indices of refraction is due to a change in what of property of light?

• amplitude

• speed

• period

• colour

The speed of light in material A is 1.25 times as large as it is in material B. What is the ratio of the refractive indices, nA/nB, of these materials?

• 1

• 1.25

• 2.5

• 0.8

Light enters a substance from air at 40° to the normal. It continues through the substance at 25° to the normal. What would be the critical angle for total internal reflection for this substance?

• 37.6 ⁰

• 41.1⁰

• 51.4⁰

• 20.5⁰

A mirage is formed because of

• reflection

• refraction

• diffraction

• interference