Question

An electrical appliance has a resistance of 4 ohms. When it is connected to a 12 V battery, the number of coulombs passing through it per second is
A: 1.2
B: 12
C: 0.3
D: 3

Answer 1

Hint: A coulomb is defined as the amount of electricity that is transmitted by a current of one ampere during a time of one seconds. It is nothing but the product of current and time. It is also termed as the unit for electric charge. In this case the number of coulombs flowing per second is nothing but the value of current. Hence we can approach the question with the help of Ohm’s law.

Formula used:
Ohm’s law: If a current of I is passing through a resistance of value R, then the potential difference would be V=IR.

Complete step by step answer:
In the question we are given that the given electrical appliance has a resistance of 4 ohms. It is connected to a 12V battery. We have to find the value of the number of coulombs passing through it per second, which is nothing but the value of current.
According to Ohm’s law,
$\begin{align}
 & V=IR \\
 & \Rightarrow I=\frac{V}{R}=\dfrac{12}{4}=3A \\
\end{align}$
Thus we can say that 3 coulombs of charge flows through the electrical appliance per second.

So, the correct answer is “Option C”.

Note:
Students must note the fact that Ohm’s law is not applicable to all electrical appliances or components.
Only the linear elements, that is, the ones that show linear dependence of current and voltage can use ohm's law. Devices like semiconductors don't show this dependency. Hence they don’t follow ohm's law.