SI unit of power of lens is
metre
horse power
dioptre
watt
The ratio of the sine of the angle of incidence to the sine of angle of refraction is constant and is called
Malu's law
Snell's law
Optical density
Relative density
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 man is using concave mirror for shaving.If his face is 20 cm from the mirror having magnification 2,what will be the radius of curvature of the mirror?
60 cm
80 cm
50 cm
40 cm
A beam of light passes from air into a substance X.If the angle of incidence be 72° and the angle of refraction be 40°,calculate the refractive index of substance X .(Given :sin 72° = 0.951 and sin 40° = 0.642)
1.48
1.62
1.75
1.22
What is called reciprocal of focal length of a lens ?
Power
Radius
Centre of curvature
Focus
Power of a lens is - 4D and for the second lens,power is + 2D.The total power for the two in contact is
6 D
-6 D
-2 D
-8 D
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
The refraction of light is commonly known as
bending
scattering
reflection
interference
The sum of the reciprocals of object distance and image distance is equal to the
focal length of a mirror
reciprocal of the focal length
radius of curvature
magnification
