Dear

  Lets find out radiation pressure Pressure F/A

  F = dp/dt

  Pressure= dp/dt/A = dp/Adt

 

  dp= 2h/   ( Multiplication by 2 is beacause of reflection remember when the ball rebounds the momentum gets multiplied by 2 )

 

Pressure = 2h/ Adt

 

For n number of photons =n

 

Pressure = n2h/ Adt

 

By substituting With intensity " I "we can write

 

  Pressure = 2I/C     C = Velocity of light

 

 

 

Reflection coefiecient

 

 

 

When an electromagnetic wave approaches a surface, it may be either absorbed (absorption coefficient=1 for complete absorption) or reflected (reflection coefficient=1 for complete reflection) or just passes straight through (transmission coefficient=1 for complete transmission). Conservation of energy demands that the sum of these coefficients is equal to unity. In the first two cases, momentum 'p' is transferred from the photon to the object whose surface is struck. In this way, a force (dp/dt) is exerted on the struck object, giving rise to EMRPressure. If the electromagnetic radiation is completely absorbed, the struck object acquires both momentum and electromagnetic energy of the photon. If the electromagnetic wave is totally reflected, so that it rebounds with the same magnitude of momentum, but oppositely directed, conservation of momentum demands that the momentum transferred to the struck object is twice the magnitude of the momentum of the incoming wave. If it keeps on going straight through, no momentum or energy is exchanged. Generally, if a beam of EM waves strikes a surface, some waves will be reflected, some will be absorbed and some keep going straight through, depending on the target's properties AND frequency