Q73 / 180 · NEET 2026 (Cancelled) · Chemistry
A bulb is rated at $150$ watt, converting $8\%$ energy into light. If energy of one photon is $4.42 \times 10^{-19}$ J, how many photons are emitted by the bulb per second ?
- Correct answerA$2.71 \times 10^{19}$
- B$3.06 \times 10^{19}$
- C$27.2 \times 10^{19}$
- D$1.35 \times 10^{19}$
Solution
Power of the bulb, $P = 150$ W
Energy converted into light per second, $E = 8\%$ of $150$ J
$E = \dfrac{8}{100} \times 150 = 12$ J
Energy of one photon, $E_p = 4.42 \times 10^{-19}$ J
Number of photons emitted per second, $n = \dfrac{E}{E_p}$
$n = \dfrac{12}{4.42 \times 10^{-19}}$
$n = 2.71 \times 10^{19}$
Answer: $2.71 \times 10^{19}$
Energy converted into light per second, $E = 8\%$ of $150$ J
$E = \dfrac{8}{100} \times 150 = 12$ J
Energy of one photon, $E_p = 4.42 \times 10^{-19}$ J
Number of photons emitted per second, $n = \dfrac{E}{E_p}$
$n = \dfrac{12}{4.42 \times 10^{-19}}$
$n = 2.71 \times 10^{19}$
Answer: $2.71 \times 10^{19}$
Hence, the correct answer is option: 'A'.