Question

A smart phone charger delivers charge to the phone, in the form of electrons, at a rate of -0.75 c/s. What is the rate of charge delivered by the charger?

1) -0.75 c/s
2) 0.75 c/s
3) 1.5 c/s
4) -1.5 c/s

Answer 1

The rate of charge delivered by the charger is 0.75 c/s, as current is a scalar quantity and is defined with respect to positive charge even if the actual charge carriers are electrons.

Step-by-step explanation:

The rate of charge delivered by a smartphone charger, which gives off charge at a rate of -0.75 coulombs per second (c/s), is asking for the magnitude of current. In physics, when we talk about the rate of charge, we refer to the magnitude, which is always a positive value because it is a scalar quantity.

Therefore, even though electrons are negatively charged, the rate at which charge is delivered by the charger is a positive value because current is defined as the flow of positive charge. The answer to the question is 0.75 c/s, which is option (2).