Questions
1
In the case of a concave mirror, the image of an object is
Answer: Real, inverted and diminished when the object lies beyond the centre of curvature
2
To increase the magnifying power of a telescope, the focal length of
Answer: Eye-piece lens should be decreased
3
Which of the following is used to split white light into different colours?
Answer: Prism
4
'Short-sight' in human eye can be corrected by using proper
Answer: concave lens
5
Which one of the following lenses should be used to correct the defect of astigmatism?
Answer: Cylindrical lens
6
A mirage occurs because of
Answer: total internal reflection by layers of air
8
Which of the following is incorrect?
Answer: The virtual image given by a concave mirror is inverted
9
What would be the number of images formed of an object in two mirrors placed at right angles to each other?
Answer: three
11
How far must an object be from a concave mirror if the image formed is to be inverted?
Answer: more than its focal length
12
How far must a girl stand in front of a concave spherical mirror of radius 120 cm to see an erect image of her face four times its natural size?
Answer: 45 cm from the mirror
13
The human eye is like a camera and hence it contains a system of lens. The eye lens forms
Answer: an inverted, real image of the object on the retina
14
The ratio of the focal length of the objective to the focal length of the eyepiece is greater than one for
Answer: a telescope
15
Which one among the following is used to make periscope?
Answer: Plane mirror
16
What type of a mirror is used in anti-shop-lifting-devices?
Answer: Convex mirror
17
Due to which phenomena the stick if immersed in water appears to be bent?
Answer: Refraction
20
Due to which phenomena light rays emerging from a cinema machine spread wide on the screen?
Answer: Diffraction
