Physics Quiz on Light

An object is placed 20 cm in front of a plane mirror. The mirror is moved 2 cm towards the object. The distance between the positions of the original and final images seen in the mirror is:

• 2 cm

• 4 cm

• 10 cm

• 22 cm

Focal length of plane mirror is

• At infinity

• Zero

• Negative

• None of these

Which of the following can make a parallel beam of light when light from a point source is incident on it?

• Concave mirror as well as convex lens

• Convex mirror as well as concave lens

• Two plane mirrors placed at 90° to each other

• Concave mirror as well as concave lens

In order to obtain a magnification of, -0.6 (minus 0.6) with a concave mirror, the object must be placed:

• At the focus

• Between pole and focus

• Between focus and center of curvature

• Beyond the center of curvature

A ray of light that strikes a plane mirror PQ at an angle of incidence of 30o, is reflected from the plane mirror and then strikes a second plane mirror QR placed at right angles to the first mirror. The angle of reflection at the second mirror is:

• 30o

• 45o

• 60o

• 90o

Image formed by plane mirror is

• Real and erect

• Real and inverted

• Virtual and erect

• Virtual and inverted

A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is

• -30 cm

• -20 cm

• -40cm

• -60 cm

A man runs towards the plane mirror at 2 m/s. The relative speed of his image with respect to him will be:

• 4 ms⁻¹

• 2 ms⁻¹

• 8 ms⁻¹

• 10 ms⁻¹

An object is placed at 100 mm in front of a concave mirror which produces an upright image (erect image). The radius of curvature of the mirror is:

• Less than 100 mm

• Between 100 mm and 200 mm

• Exactly 200 mm

• More than 200 mm

A concave mirror gives real, inverted and same size image if the object is placed

• At F

• At infinity

• At C

• Beyond C