AMU 2026 — science PYQ
AMU | science | 2026If the maximum kinetic energy of electrons is , the stopping potential is :
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If the maximum kinetic energy of electrons is 3 eV, the stopping potential is :
4 V
3 V
(Correct Answer)2 V
−2 V
3 V
In the photoelectric effect, when light of a sufficiently high frequency shines on a metal surface, electrons are emitted. The emitted photoelectrons possess a range of kinetic energies up to a certain maximum value, Kmax.
The stopping potential (V0) (or retarding potential) is the minimum negative voltage applied to the collector plate relative to the emitter plate that is just sufficient to stop the fastest moving photoelectrons from reaching the collector, thereby reducing the photoelectric current to zero.
The work done by the stopping potential in stopping the most energetic electron must equal its maximum kinetic energy. The mathematical equation representing this relationship is:
Kmax=e⋅V0
Where:
Kmax is the maximum kinetic energy of the photoelectrons.
e is the elementary charge of an electron (1.6×10−19 C).
V0 is the magnitude of the stopping potential (measured in volts, V).
We are given:
Maximum kinetic energy (Kmax) = 3 eV
Substitute the value of Kmax into the formula:
3 eV=e⋅V0
Since 1 eV=1 e⋅1 V, the unit charge factor (e) cancels out directly from both sides of the equation:
V0=3 V
Thus, the magnitude of the stopping potential needed to halt the photocurrent is 3 V.
The correct option is (b) 3 V.
In the photoelectric effect, when light of a sufficiently high frequency shines on a metal surface, electrons are emitted. The emitted photoelectrons possess a range of kinetic energies up to a certain maximum value, Kmax.
The stopping potential (V0) (or retarding potential) is the minimum negative voltage applied to the collector plate relative to the emitter plate that is just sufficient to stop the fastest moving photoelectrons from reaching the collector, thereby reducing the photoelectric current to zero.
The work done by the stopping potential in stopping the most energetic electron must equal its maximum kinetic energy. The mathematical equation representing this relationship is:
Kmax=e⋅V0
Where:
Kmax is the maximum kinetic energy of the photoelectrons.
e is the elementary charge of an electron (1.6×10−19 C).
V0 is the magnitude of the stopping potential (measured in volts, V).
We are given:
Maximum kinetic energy (Kmax) = 3 eV
Substitute the value of Kmax into the formula:
3 eV=e⋅V0
Since 1 eV=1 e⋅1 V, the unit charge factor (e) cancels out directly from both sides of the equation:
V0=3 V
Thus, the magnitude of the stopping potential needed to halt the photocurrent is 3 V.
The correct option is (b) 3 V.