Question

In the figure a particle is to be released at rest at point A and then is to be accelerated directly through point B by an electric field. The potential difference between points A and B is 100 V. Which point should be at higher electric potential if the particle is (a) an electron, (b) a proton, and (c) an alpha particle (a nucleus of two protons and two neutrons, 4He)? (d) Compute the kinetic energies of these particles at point B, and rank them greatest first. Use math formulas to prove answers

Answer 1

Answer 2

Part A)

For an electron, the higher potential needs to be at point B, since the electron is a negative charge

Part B)

Proton has a positive charge, so point A needs the higher potential

Part C)

Alpha Particle has a positive charge, so point A needs the higher potential

Part D)

KE = PE = qV

The alhpa particle has a greater charge, so greater KE

The proton and electron will be the same

For Alpha Particle

KE = 2(1.6 X 10^-19)(100)

KE = 5.0 X 10^-11 J

For the electron and proton, it will be half that since the charge is half the value

KE = 2.5 X 10^-11 J