Question

An electric heater draws a current of 5 A when connected to 220 V mains supply. Calculate the resistance of the filament used.

Answer 1

Hint: Whenever current passes through any conductor then it gets heated up. The amount of heat generated is due to the collision of the moving electrons with the ions of the conductor and more the collisions greater will be the heat generated inside it.

Complete step by step solution:
Current, i= 5 A
Potential difference, V= 220 V
We know the relationship between the voltage and current from Ohm’s law is given by: \[V=iR\]
Substituting the values, we get,
\[\begin{align}
  & 220=5R \\
 & \Rightarrow R=\dfrac{220}{5} \\
 & \Rightarrow R=48\Omega \\
\end{align}\]
So, the resistance of the conductor is 48 \[\Omega \]

Additional Information:
power and current has direct relationship. Also, the total resistance in the circuit is also determined using the formula. Ohm’s law can be applied to any conductor which is Ohmic and follows ohm’s law at all conditions of temperature and pressure. The relationship for power and the current and the resistance is given by the formula, \[P={{i}^{2}}R\]

Note:
Not all conductors obey ohm’s law. The conductors in which the current remains proportional to the applied voltage under all conditions of temperature and pressure are called ohmic conductors. Examples are copper, Aluminium, nickel etc. While there are others which do not follow ohm’s law under all conditions of temperature and pressure and they are called non ohmic. For example, mercury, in case of mercury when the temperature goes below 4 then the resistance drops to zero and starts behaving like a superconductor.