A bulb is rated at 150 watt, converting 8% energy into light. If energy of one photon is 4.42 × 10-19 J, how many photons are emitted by the bulb per second?
- 27.2 × 1019
- 4.06 × 1019
- 1.35 × 1019
- 2.71 × 1019
Answer
(4) 2.71 × 1019
Solution
Energy given out as light per second = 8% of 150 J = 8100 × 150 = 12 J
Number of photons per second = energy per secondenergy of one photon
⇒ n = 124.42 10-19 = 2.71 × 1019
Answer: (4)