1.

A narrow beam of monochromatic light of wavelength lamda emitted from a source of power P is propogating in the positive x-direction. After being reflected from a perfectly reflecting plane mirror of area vector vecA=A(-hati-hatj), the beam falls on a metal plate of surface area A[vecA is along outward normal at mirror]. the force exerted by light beam on the mirror is vecF and Deltavecp is change in momentum of each photon then [cis speed of light in vacuum]

Answer»

`DeltavecF=(P)/(C)(hati+hatj),DELTAVECP=(H)/(LAMDA)(-hati-hatj)`
`DeltavecF=(P)/(c)(hati+hatj),Deltavecp=(h)/(lamda)(hati+hatj)`
`DeltavecF=(P)/(c)(-hati-hatj),Deltavecp=(h)/(lamda)(-hati-hatj)`
`DeltavecF=(P)/(c)(-hati-hatj),Deltavecp=(h)/(lamda)(+hati+hatj)`

Solution :`|vecF|=(2Pcostheta)/(c)[bot` to mirror & directed TOWARD it]


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