Question

How much current will an electric bulb draw from a $220V$ source, if the resistance of the bulb filament is $660\Omega$? How much current will an electric heater coil draw from a $220V$ source, if the resistance of the heater is $100\Omega$?

Answer 1

Step 1: Given data and formula

Case 1: Given data,

1. Source voltage is $V=220V$
2. Resistance of the bulb filament is $R=660\Omega$

Formula:

According to Ohm's law, the formula to calculate the current in the circuit is given by

$I=\frac{V}{R}$

where $I$ is the current drawn by the electric bulb.

Step 2: Finding the current drawn by the electric bulb

Substituting the values of voltage and resistance into the formula to calculate the current.

$$\begin{gathered} I=\frac{220V}{660\Omega } \\ I=\frac{22}{66} \\ I=0.33A \end{gathered}$$

Step 3: Given data and formula

Case 2: Given data,

1. Source voltage is $V=220V$
2. Resistance of the heater is $R\text{'}=100\Omega$

Formula:

According to Ohm's law, the formula to calculate the current in the circuit is given by

$I\text{'}=\frac{V}{R\text{'}}$

Where $I\text{'}$ is the current drawn by the coil of heater.

Step 4: Finding the current drawn by the coil of the heater

Substituting the values of voltage and resistance into the formula to calculate the current.

$$\begin{gathered} I\text{'}=\frac{220V}{100\Omega } \\ I\text{'}=\frac{22}{10} \\ I\text{'}=2.20A \end{gathered}$$

Hence, an electric bulb will draw $0.33A$ current and an electric heater coil will draw $2.20A$ current.