Q27.A beam of light has two wavelengths of 4972Å and 6216Å with a total intensity of 3.6 × 10−3 Wm−2 equally distributed among the two wavelengths. The beam falls normally on an area of 1 cm2 of a clean metallic surface of work function 2.3eV. Assume that there is no loss of light by reflection and that each capable photon ejects one electron. The number of photoelectrons liberated in 2 s is approximately: (1) 6 × 1011 (2) 9 × 1011 (3) 11 × 1011 (4) 15 × 1011
What This Question Tests
This multi-concept question requires calculating the number of photons for two different wavelengths from given total intensity, checking which photons are energetic enough to cause photoemission, and then summing the emitted photoelectrons.
Concepts Tested
Formulas Used
E = hc/λ
I = N_p hf / AΔt
N_e = N_p_capable
📚 NCERT Sections This Tests
11.8 — Light Of Frequency 7.21 × 1014 Hz Is Incident On A Metal Surface.
Physics Class 12 · Chapter 11
11.8 Light of frequency 7.21 × 1014 Hz is incident on a metal surface. Electrons with a maximum speed of 6.0 × 105 m/s are ejected from the surface. What is the threshold frequency for photoemission of electrons?
11.7 — The Work Function For A Certain Metal Is 4.2 Ev. Will This Metal Give
Physics Class 12 · Chapter 11
11.7 The work function for a certain metal is 4.2 eV. Will this metal give hotoelectric emission for incident radiation of wavelength 330 nm?
11.2 — The Work Function Of Caesium Metal Is 2.14 Ev. When Light Of
Physics Class 12 · Chapter 11
11.2 The work function of caesium metal is 2.14 eV. When light of frequency 6 ×1014Hz is incident on the metal surface, photoemission of electrons occurs. What is the (a) maximum kinetic energy of the emitted electrons, (b) Stopping potential, and (c) maximum speed of the emitted photoelectrons?
📋 Question Details
- Chapter
- Dual Nature of Matter
- Topic
- Photoelectric effect
- Year
- 2014
- Shift
- 12 Apr Online
- Q Number
- Q27
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 11: Dual Nature of Radiation and Matter
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