Work From Electric Force Practice Problems

A region of space has an electric field directed vertically upward. A point charge q = +12.0 × 10^-9 C is held at rest in the electric field. When freed, the charge travels upward. The kinetic energy of the charge is found to be +3.6 µJ when it has traveled a distance of 3.40 cm. Calculate the work done by the electric force.  

A stationary particle of charge +3.25 μC is located at the origin of an XY plane. The position of the second particle of charge -4.40 μC changes from (x,y) = (-8.50 cm, 0 cm) to (x,y) = (10.0 cm, 12.5 cm). Calculate the work done by the electric force on the second particle. 

A 12 V battery does 60 J of work pumping charge across a bulb's filament. Calculate the charge that flows from the negative terminal to the battery's positive terminal.

In a photoelectric device, electromagnetic radiation moves electrons from the cathode to the anode, doing 5.3 × 10 ^-19 J of work per electron. Calculate the emf (give magnitude only) created in the device.

A 5.0 V charging adapter sends a current of 2.0 A to a device. Calculate the work the charging adapter does to pump a charge of 0.8 C.

A power supply does 32 J of work to push 4.8 × 10 ¹⁹ electrons from a positive terminal to a negative terminal on a load in a duration of 3.0 s. Calculate the emf (give magnitude only) of the power supply.

You have two-point charges, each with a charge of +35 μC, positioned 8.0 cm apart. A +0.25 μC test charge is initially placed at a point equidistant from both charges. An external force is required to shift this test charge to a location 1.5 cm closer to one of the charges. What work is necessary for the external force to move the +0.25 μC test charge from its initial position to the new location 1.5 cm nearer one of the two charges?

A proton needs to travel from the negative plate to the positive plate of a parallel-plate capacitor. The plates are separated by a 2.0 mm gap and are charged to 85 V. What is the initial kinetic energy, in units of eV, that the proton must have in order to just barely reach the positive plate?

You are experimenting with a horizontal vacuum chamber that accelerates alpha particles using a potential difference. Can alpha particles move against gravity in this setup? What potential difference is needed to balance the downward gravitational force and keep an alpha particle stationary over a distance of 1.5 cm? Assume the mass of the alpha particle is 6.64  × 10⁻²⁷ kg, and its charge is +2e (where e = 1.6 × 10⁻¹⁹ C).