1. Magnification produced by a plane mirror is ?

infinity

+1

zero

-1

Answer: +1

Explanation:


2. An object 20cm high is placed at a distance of 100 cm from a plane mirror .The size of the image will be ?

100cm

10cm

20 cm

40cm

Answer: 20 cm

Explanation:


3. If the image is formed in front of the mirror, then the image distance will be ?

neither positive nor negative

positive

negative

positive or negative depending on the size of the object

Answer: negative

Explanation:


4. If an incident ray passes through the focus, the reflected ray will ?

pass through the centre of curvature

retrace its path

be parallel to the principal axis

pass through the pole

Answer: be parallel to the principal axis

Explanation:


5. The nature of image formed by a convex mirror when the object distance from the mirror is less than the distance between pole and focal point (F) of the mirror would be ?

virtual, upright and diminished in size

virtual, upright and enlarged in size

real, inverted and enlarged in size

real, inverted and diminished in size

Answer: virtual, upright and diminished in size

Explanation:

Convex mirror always forms a virtual, erect diminished image irrespective of the position of object in front of it.


6. A10 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 ?

– 60 cm

– 40 cm

– 20 cm

– 30 cm

Answer: – 20 cm

Explanation:

Given h0 = +10 mm = + 0.1 cm h2 = – 5 mm = -0.5 cm for real image, v = – 30 cm


7. When object moves closer to convex lens, the image formed by it shift ?

first away and then towards the lens

first towards and then away from the lens

away from the lens

towards the lens

Answer: away from the lens

Explanation:

As object moves from infinity towards optical centre of the convex lens image is shifted away from its focal point and towards infinity.


8. The nature of the image formed by concave mirror when the object is placed between the focus (F) and centre of curvature (C) of the mirror observed by us is ?

virtual, upright and enlarged

virtual, erect and smaller in size

real, inverted and diminished

real, inverted and enlarged

Answer: real, inverted and enlarged

Explanation:

When object lies between C and F, the real, inverted and enlarged image is formed beyond C.


9. In which of the following, the image of an object placed at infinity will be highly diminished and point sized ?

Convex lens only

Concave mirror, convex mirror, concave lens and convex lens.

Convex mirror only

Concave mirror only

Answer: Concave mirror, convex mirror, concave lens and convex lens.

Explanation:

The incident ray coming from the object placed at infinity will be parallel to the principal axis. When the parallel beam of light incident on a mirror or lens, irrespective of their nature, after reflection/refraction, will pass or appear to pass through their principal focus. Hence highly diminished and point size image will be formed at their focus.


10. According to new cartesian sign convention ?

Focal length of both concave and convex mirrors is positive

Focal length of concave mirror is negative and that of convex mirror is positive

Focal length of concave mirror is positive and that of convex mirror is negative

Focal length of both concave and convex mirrors is negative

Answer: Focal length of concave mirror is negative and that of convex mirror is positive

Explanation:

This is because the focus of a concave mirror is in front of the mirror, on the left side, and the focus of a convex mirror is behind the mirror, on the right side.