Momentum

Step 1: Understanding the radiation momentum transfer
The momentum of a photon is given by the relation: where is the energy of the radiation and is the speed of light.
Step 2: Effect of a perfectly reflecting surface
When radiation falls normally on a perfectly reflecting surface, the total momentum transfer is due to the change in momentum. Since the surface reflects the radiation completely, the momentum change is: For a perfectly reflecting surface, the photon momentum reverses direction, meaning the change in momentum is: Thus, the total momentum transferred to the surface is: Final Answer: The correct option is , which corresponds to option (2).