Question

6.
A ray AB travelling parallel to principal axis incident on a concave mirror as shown below. If
Z BFC = 120°, then angle of incidence is
[Symbols have their usual meaning]
A
B
120°
C
F
(1) 30°
(3) 15°
(2) 60°
(4) 45°​

Answer 1

since AB || CF

so angle CFB + angle ABF = 180 ( co interior angle)

angle ABF = 180 - 120 = 60

angle ABF = angle of incidence + angle of reflection

60 = 2 angle of incidence ( because angle of incidence = angle of reflection)

30 = angle of incidence

Answer 2

Answer:

As per the data given in the above question

given,BFC = 120°,

we have to find the angle of incidence is

A concave mirror has a reflective surface that is curved inward and away from the light source. Concave mirrors reflect light inward to one focal point. Unlike convex mirrors, the image formed by a concave mirror shows different image types depending on the distance between the object and the mirror.

The principle when the light rays falls on the smooth surface, the angle of reflection is equal to the angle of incidence, also the incident ray, the reflected ray, and the normal to the surface all lie in the same plane

$so , i+r= 60°$

As according to principle,

$angle \: i = angle \: r = \frac{60}{2} = 30$Hence , angle of incidence ,i = 30°

Project code #SPJ2