Question

A
pulse of light of duration 10−6 s is absorbed completely by a small object initially at rest. If the power of the pulse is 60 × 10−3 W, calculate the final momentum of the object.

Answer 1

Answer:

t=100×10

−9

sec, P=30×10

−3

Watt,

C=3×10

8

m/s

Incident energy =Pt

By debroglie wavelength, λ=h/p

and Energy of photon is E=hc/λ

From above two equations, E=pc

Momentum p=

C

Pt

=

3×10

8

30×10

−3

×100×10

−9

=1.0×10

−17

kg ms

−1

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