Correct Answer - Option 1 : 7.73 × 10
-24 kg m s
-1
The correct answer is option 1) i.e. 7.73 × 10-24 kg m s-1
CONCEPT:
- The energy of a photon:
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Photons have wave-like and particle-like properties. Light is a form of energy and this energy comes from the energy of the photons that constitute light.
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Photon is a bundle of electromagnetic energy.
The energy of a photon (E) is given by:
\(E =\frac{hc}{λ}\)
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Momentum of a photon: The momentum (p) of a photon is related to its wavelength (λ) as follows
p = \(\frac{h}{λ}\)
Where h is Planck's constant (6.63 × 10-34 J s)
CALCULATION:
Given that:
Wavelength of the photon, λ = 600 nm = 600 × 10-9 m
We know, \(E =\frac{hc}{λ}\)
Substituting p = \(\frac{h}{λ}\) in E we get, E = pc
Since it loses 30% of its energy to the electron, the energy it will have now = 70%
If p is the initial momentum, the new momentum p' = 70% of p = 0.7p (∵ speed of light (c) is a constant)
p' = 0.7p = 0.7 × \(\frac{h}{λ}\) = 0.7 × \(\frac{6.63 × 10^{-34}}{600 × 10^{-9}}\) = 7.73 × 10-28 kg m s-1
