JEE Main202330 Jan 2023Morning ShiftPhysicsDual Nature of MatterActual
A small object at rest, absorbs a light pulse of power 20 mW and duration 300 ns . Assuming speed of light as 3 × 10 8 m s - 1 . The momentum of the object becomes equal to :
Options
- A0 . 5 × 10 - 17   kg   m   s - 1
- B2 × 10 - 17   kg   m   s - 1
- C3 × 10 - 17   kg   m   s - 1
- D1 × 10 - 17   kg   m   s - 1
Correct answer
B. 2 × 10 - 17   kg   m   s - 1
Step-by-step solution
Momentum p = Energy E Speed   of   light c = Power × time c = 20 × 10 - 3 W 300 × 10 - 9 s 3 × 10 8   m   s - 1 = 2 × 10 - 17   kg   m   s - 1 As momentum is conserved, therefore momentum of object will be 2 × 10 - 17   kg   m   s - 1 .