1.

Light with an energy flux` 20 W//cm^2` falls on a non-reflecting surface at normal incidence. If the surface has an area of `30 cm^2`. the total momentum delivered ( for complete absorption)during 30 minutes isA. `36 xx 10^5 kg-m//s`B. `36xx10^4 kg-m//s`C. `1.08 xx 10^4 kg -m//s`D. `1.08xx10^7 kg-m//s`

Answer» Correct Answer - B
In case of perfectly non reflecting surface,
`Deltap=E/c`
where
`e = 20xx30xx30xx60`
`= 1.08xx10^6 j`
`Deltap=(1.08xx10^6)/(3xx10^8)`
`36xx10^-4 kg-m//s`.


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