How much work does a $12\mathrm{V}$ battery do when it moves $2.4\mathrm{C}$ from the negative terminal to the positive terminal?

The luminous efficiency of a lightbulb is the ratio of luminous flux to electric power input.

(a) What is the luminous efficiency of a 100-W, 1600-lm bulb?

(b) How many 40-W, 60-lm/W fluorescent lamps would be needed to provide an illuminance of 250 lm/m² on a factory floor of area 22 m x 30 m? Assume the lights are 10 m above the floor and that half their flux reaches the floor.

An electron moves from point A to point B. The potential difference between these two points is 100 V. What is 

a. the point of higher potential?

b. the work done on the electron?

c. the final speed of the electron if its initial speed is zero?

What work is needed to assemble an equilateral triangle of side length 5 cm, with a 5µC charge at each vertex?

A particle with charge $+4.20$ nC is in a uniform electric field $E$ directed to the left. The charge is released from rest and moves to the left; after it has moved $6.00$ cm, its kinetic energy is $+2.20x{10}^{-6}$ J. What is the work done by the electric force?

A point charge $q_1=+2.40$ $\mu$C is held stationary at the origin. A second point charge $q_2=-4.30$ $\mu$C moves from the point $x=0.150$ m, $y=0$ to the point $x=0.250$ m, $y=0.250$ m. How much work is done by the electric force on $q_2$?

How much charge does a 9.0 V battery transfer from the negative to the positive terminal while doing 27 J of work?

Light from the sun allows a solar cell to move electrons from the positive to the negative terminal, doing 2.4×10⁻¹⁹ J of work per electron. What is the emf of this solar cell?