Question:medium
\( 10^{20} \) photons of wavelength 660 nm are emitted per second from a lamp. The wattage of the lamp is:
\[
\text{(Planck's constant} \, h = 6.6 \times 10^{-34} \, \text{Js})
\]
\( 10^{20} \) photons of wavelength 660 nm are emitted per second from a lamp. The wattage of the lamp is:
\[
\text{(Planck's constant} \, h = 6.6 \times 10^{-34} \, \text{Js})
\]
Show Hint
To find the power emitted by a lamp that emits photons, first calculate the energy of each photon using Planck's equation, then multiply by the number of photons emitted per second.
Updated On: Nov 28, 2025
- 30 W
- 60 W
- 100 W
- 500 W
Top Questions on Photoelectric Effect
- The work function of a metal is 2 eV. What is the threshold frequency for the photoelectric emission? (Take Planck's constant $ h = 6.63 \times 10^{-34} \, \text{Js} $, $ 1 \, \text{eV} = 1.6 \times 10^{-19} \, \text{J} $)
- BITSAT - 2025
- Physics
- Photoelectric Effect
- If \(\phi\) is the work function of photosensitive material in eV and light of wavelength of numerical value \(\lambda = \frac{hc}{e}\) metre, is incident on it with energy above its threshold value at an instant then the maximum kinetic energy of the photo-electron ejected by it at that instant (Take \(h\)-Planck’s constant, \(c\)-velocity of light in free space) is (in SI units):
- NEET (UG) - 2024
- Physics
- Photoelectric Effect
- The maximum kinetic energy of the photoelectrons varies.
- MHT CET - 2024
- Physics
- Photoelectric Effect
- Want to practice more? Try solving extra ecology questions todayView All Questions