Question

The angle between an incident ray and the mirror is ${60}^0$. Total angle turned by the ray of light is:

• A. ${60}^0$
• B. ${120}^o$
• C. ${30}^o$
• D. ${90}^o$

Answer 1

Answer: (B)

${120}^o$

Glancing angle of incidence$={60}^0$, given.

So, angle of incidence $={90}^0-{60}^0={30}^0$

And, obviously, angle of reflection$={30}^0$

$\therefore$ total angle turned by the ray$=$ angle of deviation $={180}^0-$ angle of incidence$+$angle of reflection$={180}^0-[{30}^0+{30}^0]={120}^0$