Question

A right-angled prism is set to deviate a ray of light through ${90}^o$ . If the same prism is to be used for deviating through ${180}^o$ , the prism must be turned from the previous set position through the angle :

• A. ${45}^o$
• B. ${90}^o$
• C. ${135}^o$
• D. ${180}^o$

Answer 1

The correct option is A ${45}^o$

From the figure we can see that the right angled prism needs to be rotated by ${45}^{\circ }$.

Hence the correct answer is option (A).