Question

while doing an experiment to verify the law of reflection of sound an angel between one tube and normal is 40°,the perfect reflection of sound will take place only when:
(a) angel between the two tubes is 40°
(b) angel between the two tubes is 20°

Answer 1

We are given the angles between normal at the point of incidence and incident ray as 40°

we know that angles of incidence = angles of reflection = 40°

so angle of reflection = 40°

angle of reflection + angle of incidence = 40 +40 = 80°

so none of the options given above is correct.

the correct answer should be :

the angle between both the tubes should be 80° to hear the sound clearly