The threshold frequency for a certain metal is ... - SS2 Physics Modern Physics - Quantum Mechanics Question
The threshold frequency for a certain metal is 5.0 × 1014 Hz. If light with a frequency of 6.0 × 1014 Hz is incident on the metal, calculate the kinetic energy of the emitted electrons. The work function of the metal is 4.0 eV.
To calculate the kinetic energy of the emitted electrons, we first need to determine if the incident light has enough energy to overcome the work function of the metal. If the frequency of the light is greater than or equal to the threshold frequency, it can emit electrons. In this case, the frequency (6.0 × 1014 Hz) is greater than the threshold frequency (5.0 × 1014 Hz), so electrons will be emitted.
The energy of a photon can be calculated using the equation: E = hf, where E is the energy, h is Planck's constant (6.63 × 10-34 J·s), and f is the frequency.
E = (6.63 × 10-34 J·s) × (6.0 × 1014 Hz) = 3.98 × 10-19 J
The kinetic energy of the emitted electrons can be calculated by subtracting the work function from the energy of the incident photons:
Kinetic energy = E - Work function
Kinetic energy = (3.98 × 10-19 J) - (4.0 eV × 1.6 × 10-19 J/eV)
= -2.88 × 10-20 J
Note: The negative sign indicates that the electrons have lost energy, which is consistent with the emission of electrons in the photoelectric effect.
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