Understanding the Concepts
* Photon Energy: Photons are packets of light energy. Their energy (E) is related to their frequency (ν) by Planck's constant (h): E = hν.
* Photon Momentum: Photons also have momentum (p). The relationship between energy and momentum for a photon is: E = pc, where c is the speed of light.
Calculation
1. Convert eV to Joules:
* 1 eV = 1.602 x 10⁻¹⁹ J
* So, 140 eV = 140 * 1.602 x 10⁻¹⁹ J = 2.243 x 10⁻¹⁷ J
2. Calculate Momentum:
* p = E/c
* p = (2.243 x 10⁻¹⁷ J) / (3 x 10⁸ m/s)
* p ≈ 7.48 x 10⁻²⁶ kg m/s
Therefore, the momentum of a 140 eV photon is approximately 7.48 x 10⁻²⁶ kg m/s.
