Question:
Electron-positron annihilation produces photons. Momentum of each photon is: (m = $9\times10^{-31}$ kg)
Electron-positron annihilation produces photons. Momentum of each photon is: (m = $9\times10^{-31}$ kg)
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Photon momentum: $p = \frac{E}{c}$.
Updated On: Jun 17, 2026
- $36\times10^{-23}$ kg m s$^{-1}$
- $9\times10^{-23}$ kg m s$^{-1}$
- $27\times10^{-23}$ kg m s$^{-1}$
- $18\times10^{-23}$ kg m s$^{-1}$
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The Correct Option is C
Solution and Explanation
Step 1: Electron and positron annihilate at rest, so total energy: \[ E = 2mc^2 \]
Step 2: Each photon has energy: \[ E_\gamma = mc^2 \]
Step 3: Photon momentum: \[ p = \frac{E}{c} = mc \]
Step 4: Substitute: \[ p = 9\times10^{-31} \times 3\times10^8 \]
Step 5: \[ p = 27\times10^{-23}\ \text{kg m s}^{-1} \]
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