JEE Advanced2013PhysicsDual Nature of MatterActual
A pulse of light of duration 100 ns is absorbed completely by a small object initially at rest. Power of the pulse is 30 mW and the speed of light is 3 ×10 8 ms -1 . The final momentum of the object is
Options
- A0.3 × 1 0 - 1 7 kg ms -1
- B1.0 × 1 0 - 1 7 kg ms -1
- C3.0 × 1 0 - 1 7 kg ms -1
- D9.0 × 1 0 - 1 7 kg ms -1
Correct answer
B. 1.0 × 1 0 - 1 7 kg ms -1
Step-by-step solution
Power = E t E = Energy ∴ E = Power × time = hc λ hc λ = 3 0 × 1 0 - 3 × 1 0 0 × 1 0 - 9 ∴ p = h λ = 3 × 1 0 - 9 3 × 1 0 8 = 1 × 1 0 -1 7 kg ms