As a result of annihilation of electron and positron, number of γ-ray (Gama ray) photons are: ________?
Correct answer: A. Two
- A. Two
- B. Three
- C. Four
- D. One
Explanation
When an electron and positron annihilate at rest, their rest energy is converted into two gamma-ray photons moving in opposite directions so that momentum is conserved. Students may choose one photon by applying only energy conservation and overlooking the need to conserve momentum.
Last updated
About Photons and the Particle Model of Light
The particle model treats light as photons with energy E equals hf and momentum related to wavelength. Questions involve the photoelectric effect, work function, threshold frequency, stopping potential and photon energy, while distinguishing particle behaviour from the wave description of interference and diffraction.
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.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
A ball of mass 1g is moving with a velocity of 10³ m/s. The De_Broglie wavelength of the ball is:
A beam of light of wavelength "λ" and with illumination "L" falls on a clean surface of sodium. If "N" photoelectron are emitted each with kinetic energy E:
A change in energy of a photon occurs when it collides with an electron at rest and is known as:
A device whose working is based upon photoelectric effect is:
A particle of mass 5 mg moves with a speed of 8 m/s. Calculate its de Broglie wavelength (h = 6.63 x 10^-34 J s).