If radiation is totally absorbed and energy incident on surface in time $t$ be $U$,then write the equation for the momentum imparted to the surface.

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(A) The relationship between the energy $U$ of electromagnetic radiation and its momentum $p$ is given by $p = U/c$,where $c$ is the speed of light.
When radiation is totally absorbed by a surface,the entire momentum of the incident radiation is transferred to the surface.
Therefore,the momentum imparted to the surface is $p = U/c$.

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