RAY OPTICS BASICS

What are the laws of reflection ?

• angle of incidence = angle of reflection

• incident ray , reflected ray and the normal at the point of incidence all are in the same plane

• incident ray , refracted ray and the normal at the point of incidence all are in the same plane

What are the laws of refraction ?

• angle of incidence = angle of reflection

• incident ray , refracted ray and the normal at the point of incidence all are in the same plane

• incident ray , reflected ray and the normal at the point of incidence all are in the same plane

Radius of curvature of a plane mirror

• zero

• infinity

• can be zero or infinity

• 25 cm

Angle between the incident and reflected ray falling on a plane mirror is 60⁰ . Find the angle of incidence ( i )and reflection (r)

• i = r = 60

• i = r = 30

• i = r = 45

• i = 30 , r = 60

Image formed by a plane mirror is

• real inverted and magnified

• virtual erect and enlarged

• virtual erect and same size

• virtual erect and diminished

Image formed by a plane mirror is

• real inverted and magnified

• virtual erect and enlarged

• virtual erect and same size

• virtual erect and diminished

Focal length of a convex mirror of radius of curvature (R) 20 cm is

• f = -20 cm

• f =-10 cm

• f = +10 cm

• f = +20 cm

• f = +40 cm

Focal length of a concave mirror of radius of curvature (R) 20 cm is

• f = -20 cm

• f =-10 cm

• f = +10 cm

• f = +20 cm

• f = +40 cm

A concave mirror forms complete image of a small candle placed in front of it on a screen. If the lower half of the mirror is cut and removed (or painted black) .

• complete image will be formed

• Half of the image will be formed

• intensity (brightness) of the image decreases

• Intensity (brightness) of the image remains the same

A convex lens forms complete image of a small candle placed in front of it on a screen. If lower half of the lens is painted black.

• complete image will be formed

• Half of the image will be formed

• intensity (brightness) of the image decreases

• Intensity (brightness) of the image remains the same