Video Transcript
A charge of 10 coulombs flows
through a circuit in a time of five seconds. What is the current in the
circuit?
In this question, we’ve been asked
to find the current in an electric circuit. Let’s begin by recalling that
electric current is the flow of electric charge and that current is measured in
units of amperes. Specifically, the electric current
in a circuit measures how much charge flows past a point in the circuit in one
second. To calculate current, represented
by capital 𝐼, we use the formula 𝐼 equals 𝑄 divided by 𝑡, where 𝑄 is the amount
of charge that flows by over some time 𝑡. Here, we’ve been told that over
five seconds, a charge of 10 coulombs flows through the circuit. Therefore, we have that the charge
𝑄 equals 10 coulombs and the time 𝑡 equals five seconds.
Since we have values for 𝑄 and 𝑡,
let’s go ahead and substitute them into the formula for current. We have 𝐼 equals 𝑄 divided by 𝑡
or 𝐼 equals 10 coulombs divided by five seconds. But before we move on, let’s think
about the units here. It’s important to remember that
current is measured in amperes and that one ampere is equal to one coulomb divided
by one second.
Now, looking back at the units in
our equation, we see coulombs divided by seconds, which is the same thing as
amperes. This is a good sign since after
all, we’re working to find a current value and current is measured in units of
amperes. Now, getting back to the math, we
have 10 divided by five, which is equal to two. And we’re working in units of
amperes, so we know that the current 𝐼 equals two amperes. Therefore, we have found that the
current in the circuit is two amperes.
