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Examoogle • User • info@examoogle.com • EE-2024-8821
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Calculate the kinetic energy of an electron accelerated through a potential difference of 500 V.
8×10−17 J
1.6×10−17 J
5×10−17 J
4×10−16 J
8×10−17 J
The kinetic energy gained by a charged particle accelerated through an electric potential difference is equal to the work done on the particle by the electric field. This is calculated using the product of the charge of the particle and the potential difference.
The kinetic energy gained by a charged particle accelerated through an electric potential difference is equal to the work done on the particle by the electric field. This is calculated using the product of the charge of the particle and the potential difference.
Think of the potential difference as the 'height' of a slope and the electron as a ball rolling down it; the higher the voltage, the more 'speed' (kinetic energy) the electron gains by the time it reaches the bottom.
Remember 'KE = qV' (Kinetic Energy equals quality Voltage).
K=qV — Relation between kinetic energy, charge, and potential difference
q=1.6×10−19 C — Fundamental charge of an electron
When an electron with charge q=1.6×10−19 C is moved through a potential difference V=500 V, the work done W is given by W=qV. Since this work done is entirely converted into kinetic energy K, we calculate K=(1.6×10−19 C)×(500 V)=800×10−19 J, which simplifies to 8×10−17 J.
The electron volt (eV) is a unit of energy equal to 1.6×10−19 J.
Energy gained is independent of the path taken, provided the potential difference is constant.
Potential difference acts as an 'electric pressure' pushing the charge.
Allows direct conversion between electrical potential and particle speed.
Does not account for relativistic effects if the electron is accelerated to speeds approaching the speed of light.
Electron microscopes
Cathode ray tubes
The charge of an electron is 1.602×10−19 C.
Option B, C, and D are incorrect calculations resulting from misapplying the powers of ten or the multiplication factor.
A is correct — The kinetic energy is the product of the charge of the electron (1.6×10−19 C) and the potential difference (500 V), yielding 8×10−17 J.
When solving for energy in electrostatics, always ensure your charge is in Coulombs and potential is in Volts to get the answer directly in Joules.