Question

What is the resistance of an electric arc lamp, if the lamp uses $20A$ when connected to a $220V$?

Answer 1

Ohm’s law can be stated as that electric current in the circuit is directly proportional to the voltage applied and inversely proportional to the resistance. This law gives us the relation between voltage, resistance, and electric current. To answer the above question we need to use this ohm’s law. To find the resistance we need to rearrange this formula and substitute the values.

Complete step by step answer:
Given that the electric lamp uses electric current $20A$ and voltage $220V$.
We can write ohm’s law mathematically,
$V = IR$
Here, $V$ is the voltage
$I$ is the electric current
$R$ is the resistance
Rearranging the above formula,
$\dfrac{V}{I} = R$
$\dfrac{{220}}{{20}} = R$
$\Rightarrow R = 11\Omega$
Therefore the resistance offered by the electric lamp is $11\Omega$

Note: As we see in the above problem ohm’s can be applied to determine either the voltage or current or resistance. This can be applied in a linear electric circuit in which the other two values are given. It can also be applied to power calculations. Ohm’s law was discovered by the German scientist Georg Simon Ohm. Ohm’s law is said to be one of the most fundamental laws in electricity. In unilateral networks, ohm’s law is not applicable. A unilateral network means that the network allows the current to flow in one direction.