Q17.Two identical photocathodes receive the light of frequencies f1 and f2 respectively. If the velocities of the photo-electrons coming out are v1 and v2 respectively, then (1) v21 −v22 = 2mh [f1 −f2] (2) v21 + v22 = 2hm [f1 + f2] (3) 2 h 21 (4) 2 h 21 v1 + v2 = [ m (f1 + f2)] v1 −v2 = [ m (f1 −f2)]
What This Question Tests
This question applies Einstein's photoelectric equation to relate the velocities of photoelectrons to the frequencies of incident light and the work function of the photocathode.
Concepts Tested
Formulas Used
KE_max = hf - Φ
KE_max = 1/2 mv²
📚 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?
11.3 — The Photoelectric Cut-Off Voltage In A Certain Experiment Is 1.5 V.
Physics Class 12 · Chapter 11
11.3 The photoelectric cut-off voltage in a certain experiment is 1.5 V. What is the maximum kinetic energy of photoelectrons emitted?
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
- 2021
- Shift
- 17 Mar Shift 2
- Q Number
- Q17
- Type
- MCQ
- NCERT Ref
- Class 12 Physics Ch 11: Dual Nature of Radiation and Matter
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