Light of frequency 1.5 times the threshold frequency is incident on a photosensitive material. If the frequency is halved and intensity doubled, the photoelectric current becomes:
Correct answer: D. Zero times the original current
- A. 4 times the original current
- B. 2 times the original current
- C. Half the original current
- D. Zero times the original current
Explanation
Original frequency = 1.5v₀. Halving gives 0.75v₀, which is below the threshold frequency v₀, so no photoelectrons are emitted, regardless of intensity.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Dawn of Modern Physics
Classical physics cannot explain blackbody radiation and related observations, leading to Planck’s quantum theory, in which energy is emitted or absorbed in discrete packets. Photons provide the particle model of light, with energy and momentum linked to frequency and wavelength, including the photoelectric effect and its threshold frequency.
Practise Dawn of Modern Physics
739 free Dawn of Modern Physics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Dawn of Modern Physics questions
The graph between the frequency of incident light and the stopping potential is a:
A metallic surface ejects photoelectrons when hit by green light but none when hit by yellow light. Will electrons be ejected if the same surface is hit by red light?
The human eye can barely detect yellow light (6000 Å) that delivers 1.7 × 10⁻¹⁸ watt to the retina. Nearly how many photons per second does the retina receive?
What is the force exerted by a photon of intensity 1.4 kW/m² if it falls on a perfect absorber of radius 2 meters?
The rest mass of a photon is:
Which of the following graphs correctly represents the variation of particle momentum with associated de broglie wavelength?