| Question (1):
The bending of a beam of light when it passes obliquely from one medium to another is known as _______. |
| 1. |
reflection
|
| 2. |
refraction
|
| 3. |
dispersion |
| 4. |
deviation |
|
| Ans: 2 |
|
| Question (2):
The part of the lens through which the ray of light passes without suffering deviation is called ________. |
| 1. |
optical centre
|
| 2. |
focus
|
| 3. |
centre of curvature |
| 4. |
pole |
|
| Ans: 1 |
|
| Question (3):
Convex lens always gives a real image if the object is situated beyond _______. |
| 1. |
optical centre
|
| 2. |
centre of curvature
|
| 3. |
focus |
| 4. |
radius of curvature |
|
| Ans: 3 |
|
| Question (4):
Parallel rays of light entering a convex lens always converge at _______. |
| 1. |
centre of curvature
|
| 2. |
the principal focus
|
| 3. |
optical centre |
| 4. |
the focal plane |
|
| Ans: 2 |
|
| Question (5):
Where should an object be placed so that a real and inverted image of the same size is obtained, using a convex lens? |
| 1. |
Between O and F
|
| 2. |
At F
|
| 3. |
At 2 F |
| 4. |
At infinity |
|
| Ans: 3 |
|
| Question (6):
SI unit of the power of a lens is ___________. |
| 1. |
dioptre
|
| 2. |
cm
|
| 3. |
metre |
| 4. |
watt |
|
| Ans: 1 |
|
| Question (7):
1 D is the power of the lens of focal length of ______ cm. |
| 1. |
100
|
| 2. |
10
|
| 3. |
1/100 |
| 4. |
1/10 |
|
| Ans: 1 |
|
| Question (8):
In a simple microscope lens used is __________. |
| 1. |
biconvex
|
| 2. |
biconcave
|
| 3. |
plano convex |
| 4. |
cylindrical |
|
| Ans: 1 |
|
| Question (9):
Reciprocal of focal length in metres is known as the ______ of a lens. |
| 1. |
focus
|
| 2. |
power
|
| 3. |
power of accommodation |
| 4. |
far point |
|
| Ans: 2 |
|
| Question (10):
A convex lens is called _________. |
| 1. |
converging lens
|
| 2. |
diverging lens
|
| 3. |
both converging and diverging lens |
| 4. |
refracting lens |
|
| Ans: 1 |
|
| Question (11):
A positive magnification greater than unity indicates _____________________. |
| 1. |
real image
|
| 2. |
virtual image
|
| 3. |
neither real not virtual image |
| 4. |
distorted image |
|
| Ans: 2 |
|
| Question (12):
The power of a convex lens of focal length 50 cm is ______. |
| 1. |
+ 2D
|
| 2. |
- 2D
|
| 3. |
50 D |
| 4. |
- 5D |
|
| Ans: 1 |
|
| Question (13):
The focal length of a lens whose power is -1.5 D is _______. |
| 1. |
-66.66 cm
|
| 2. |
+ 1.5 m
|
| 3. |
+ 66.66 cm |
| 4. |
-1.5 m |
|
| Ans: 1 |
|
| Question (14):
Real images formed by single convex lenses are always ________________. |
| 1. |
on the same side of the lens as the object
|
| 2. |
inverted
|
| 3. |
erect |
| 4. |
smaller than the object |
|
| Ans: 2 |
|
| Question (15):
An object is placed 12 cm from a convex lens whose focal length is 10 cm. The image must be. |
| 1. |
virtual and enlarged
|
| 2. |
virtual and reduced in size
|
| 3. |
real and reduced in size |
| 4. |
real and enlarged |
|
| Ans: 4 |
|
| Question (16):
When a person uses a convex lens as a simple magnifying glass, the object must be placed at a distance. |
| 1. |
less than one focal length
|
| 2. |
more than one focal length
|
| 3. |
less than twice the focal length |
| 4. |
more than twice the focal length |
|
| Ans: 1 |
|
| Question (17):
The image produced by a concave lens is ________. |
| 1. |
always virtual and enlarged
|
| 2. |
always virtual and reduced in size
|
| 3. |
always real |
| 4. |
sometimes real, sometimes virtual |
|
| Ans: 2 |
|
| Question (18):
A virtual image is formed by _______. |
| 1. |
a slide projector in a cinema hall
|
| 2. |
the ordinary camera
|
| 3. |
a simple microscope |
| 4. |
telescope |
|
| Ans: 3 |
|
| Question (19):
An object is placed 25 cm from a convex lens whose focal length is 10 cm. The image distance is ________ cm. |
| 1. |
50 cm
|
| 2. |
16.66 cm
|
| 3. |
6.66 cm |
| 4. |
10 cm |
|
| Ans: 2 |
|
| Question (20):
The least distance of distinct vision is ______. |
| 1. |
25 cm
|
| 2. |
25 m
|
| 3. |
0.25 cm |
| 4. |
2.5 m |
|
| Ans: 1 |
|
| Question (21):
A convex lens has a focal length of 20 cm. Its power in dioptres is ___________. |
|
|
| Ans: 2 |
|
| Question (22):
An object is placed before a concave lens. The image formed _____________-. |
| 1. |
is always erect
|
| 2. |
may be erect or inverted
|
| 3. |
is always inverted |
| 4. |
is always real |
|
| Ans: 1 |
|
Question (23):
A ray of light travels from a medium of refractive index n1 to a medium of refractive index n2. If angle of incidence is i and the angle of refraction is r.
Then  is equal to |
| 1. |
n1
|
| 2. |
n2
|
| 3. |
n21 |
| 4. |
n12 |
|
| Ans: 3 |
|
| Question (24):
Two thin lenses of power +5 D and -2 D are placed in contact with each other. Focal length of the combination is |
| 1. |
+3 m
|
| 2. |
-3 m
|
| 3. |
0.33 m |
| 4. |
-0.33 m |
|
| Ans: 3 |
|
| Question (25):
The lens formula in cartesian frame is ______________. |
|
|
| Ans: 3 |
|
