Stopping Potential and its Significance
The minimum negative potential applied to the collector plate that completely stops the photocurrent, indicating the maximum kinetic energy of photoelectrons.
What is Stopping Potential and its Significance?
The minimum negative potential applied to the collector electrode with respect to the emitter electrode, at which the photoelectric current becomes zero.
Key formula / rule: Relation between Stopping Potential and Maximum Kinetic Energy
Key points
- Define stopping potential.
- Explain the experimental setup to measure stopping potential.
- Relate stopping potential to the maximum kinetic energy of photoelectrons.
- Understand the dependence of stopping potential on frequency and intensity of incident light.
Common exam trap
Confusing stopping potential with the threshold potential.
Definitions
- Term
Stopping Potential (V₀)
- Meaning
The minimum negative potential applied to the collector electrode with respect to the emitter electrode, at which the photoelectric current becomes zero.
- Term
Photoelectron
- Meaning
An electron emitted from a material as a result of the photoelectric effect.
- Term
Work Function (Φ)
- Meaning
The minimum energy required to remove an electron from the surface of a solid.
Learning objectives
Define stopping potential.
Explain the experimental setup to measure stopping potential.
Relate stopping potential to the maximum kinetic energy of photoelectrons.
Understand the dependence of stopping potential on frequency and intensity of incident light.
Apply Einstein's photoelectric equation.
Formulae
- Name
Relation between Stopping Potential and Maximum Kinetic Energy
- Note
Where KEmax is the maximum kinetic energy of photoelectrons, e is the elementary charge, and V₀ is the stopping potential.
- Expression
KEmax = e V₀
- Name
Einstein's Photoelectric Equation (modified for V₀)
- Note
Where h is Planck's constant, ν is the frequency of incident radiation, and Φ is the work function of the metal.
- Expression
e V₀ = hν - Φ
- Name
Stopping Potential in terms of frequency and work function
- Note
This shows V₀ is linearly dependent on frequency ν and independent of intensity.
- Expression
V₀ = (hν/e) - (Φ/e)
Prerequisites
Photoelectric effect
Work function of a metal
Kinetic energy
Electric potential and potential difference
Electromagnetic waves (nature of light)
Common mistakes
Confusing stopping potential with the threshold potential.
Assuming stopping potential depends on light intensity.
Incorrectly applying Einstein's photoelectric equation.
Forgetting the negative sign associated with the collector plate potential.
Keywords
Stopping Potential
Cut-off Potential
Photoelectric Effect
Photoelectrons
Maximum Kinetic Energy
Work Function
Einstein's Photoelectric Equation
Frequency
Intensity
Planck's Constant
Practice preview
The stopping potential V_0 for a certain metal is measured for different frequencies of incident light. A graph is plotted between V_0 and frequency (ν). The slope of the graph will be:…
medium
What is the stopping potential?…
easy
When monochromatic light of frequency ν is incident on a metal surface, the stopping potential is V_s. If the frequency is increased to 2ν, the new stopping potential is V_s'. If the frequency is decreased to ν/2, the st…
hard