In the photoelectric effect, if the frequency of incident light is doubled, what
Practice Questions
Q1
In the photoelectric effect, if the frequency of incident light is doubled, what happens to the kinetic energy of the emitted electrons?
It doubles
It quadruples
It remains the same
It becomes zero
Questions & Step-by-Step Solutions
In the photoelectric effect, if the frequency of incident light is doubled, what happens to the kinetic energy of the emitted electrons?
Correct Answer: Kinetic energy increases by a factor of four.
Step 1: Understand the photoelectric effect. It is the phenomenon where light causes electrons to be emitted from a material.
Step 2: Know the formula for kinetic energy (KE) of emitted electrons: KE = hf - φ, where 'h' is Planck's constant, 'f' is the frequency of the incident light, and 'φ' is the work function of the material.
Step 3: Recognize that if the frequency 'f' of the incident light is doubled, we replace 'f' with '2f' in the formula.
Step 4: Substitute '2f' into the kinetic energy formula: KE = h(2f) - φ.
Step 5: Simplify the equation: KE = 2hf - φ.
Step 6: Compare the new kinetic energy (2hf - φ) with the original kinetic energy (hf - φ).
Step 7: Notice that the new kinetic energy is twice the original kinetic energy plus the same work function φ, which means the kinetic energy increases.
Step 8: Understand that since KE is proportional to frequency, if the frequency is doubled, the kinetic energy increases by a factor of four (since KE is proportional to the square of the frequency).
