The focal lengths of four convex lenses P,Q,R and S are 20 cm,15 cm,5 cm and 10 cm, respectively.The lens having greatest power is :
P
Q
R
S
If R is the radius of curvature of a spherical mirror and f is its focal length,then :
R = f
R = 2f
R = f/2
R = 3f
A converging lens has a focal length of 50 cm.The power of this lens is :
+0.2 D
-2.0 D
+2.0 D
-0.2 D
Light enters from air into a glass plate having refractive index 1.50. What is the speed of light in glass ?(The speed of light in vacuum is 3 x 108 m/s)
2 x 108 m/s
1.82 x 108 m/s
4 x 108 m/s
2 x 106 m/s
The middle point of spherical mirror is :
Focus
Center of curvature
Pole
Axial point
The refraction of light is commonly known as
bending
scattering
reflection
interference
Linear magnification (m) produced by a rear view mirror fitted in vehicles :
is equal to one
is less than one
is more than one
can be more or less than one depending on the position of object
A concave mirror cannot be used as :
a magnifying mirror
a torch reflector
a dentist's mirror
a rear view mirror
The focal length of a spherical mirror of radius of curvature 30 cm is :
10 cm
15 cm
20 cm
30 cm
The mirror used in astronomical telescope :
Concave
Convex
Spherical
Plano-convex lenses
