In the given figure, two mirrors P and Q are situated at an angle of 60°with each other and a ray of light is incident on mirror P at an angle of 55°. What is the value of angle A if the ray again reflected by the mirror Q?
A 35°
B 55°
C 50°
D 70°
Ans 5:
Ans 6:
Class : Class 7
Answer is (a). This is observed due to this reasonThere's a line which is making an angle 55° and is a linear pair. Hence the angle of line (mirror) p is 180°. But 55° is not the angle of incidence. To get the sum of angle of incidence and reflection, we multiply 55° by 2 and get 70°. Since angle of incidence =angle of reflection, 70°÷2=35°. The angle of incident ray and the reflected ray of P and Q are same thus the sum of the angle of incidence and angle of reflection would be the same (70°). We know, angle of incidence=angle of reflection, hence 70°÷2=35°. Or A=35°