NEET 2026 (Phase 1) · ChemistryPrevious Year Question
A bulb is rated at $150$ watt, converting $8\%$ of its energy into light. If the energy of one photon is $4.42 \times 10^{-19}$ J, how many photons are emitted by the bulb per second?
- A.$2.71 \times 10^{19}$✓
- B.$4.06 \times 10^{19}$
- C.$27.2 \times 10^{19}$
- D.$1.35 \times 10^{19}$
Correct Answer
(A) $2.71 \times 10^{19}$
Solution & Explanation
\textbf{Answer:} (A) $2.71 \times 10^{19}$ \textbf{Solution:} Energy per second $= 150$ J. Energy converted to light $= 150 \times \dfrac{8}{100} = 12$ J. Number of photons $= \dfrac{12}{4.42 \times 10^{-19}} = 2.71 \times 10^{19}$.
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