1. Use the relation between energy and momentum for radiation

For electromagnetic radiation (photons), the momentum associated with energy $E$ is

$p = \frac{E}{c}$

where $c$ is the speed of light.

2. Effect of reflection from a perfectly reflecting surface

The radiation falls normally on the surface and is perfectly reflected.

• Initial momentum of radiation toward the surface: $p_i = \frac{E}{c}$
• After reflection, the radiation reverses direction, so final momentum is: $p_f = -\frac{E}{c}$

3. Change in momentum of radiation

$\Delta p_{\text{radiation}} = p_f - p_i = -\frac{E}{c} - \frac{E}{c} = -\frac{2E}{c}$

So the magnitude of change in momentum of radiation is

$\left|\Delta p_{\text{radiation}}\right| = \frac{2E}{c}$

4. Momentum transferred to the surface

By conservation of momentum, the surface receives equal and opposite momentum. Hence the momentum transferred to the surface is

$\frac{2E}{c}$

5. Check options

• A: $Ec$ — incorrect
• B: $2E/c$ — correct
• C: $E/c$ — incorrect
• D: $E/c^2$ — incorrect

Therefore, the correct answer is Option B.