Question

You set up a simple circuit with a 30W bulb with 40Ω resistance, attached to a cell of unknown voltage.

You attach an ammeter to the circuit before the bulb and attach a voltmeter in a parallel circuit around the bulb



a) The ammeter measures the current as 3A. Calculate the voltage.

Answer 1

Using Ohm's Law and the given current of 3A with the resistance of 40Ω, the voltage of the cell is calculated to be 120 volts.

Step-by-step explanation:

To calculate the voltage of the cell in the circuit with a 30W bulb with 40Ω resistance an ammeter is used to measure the current before the bulb and a voltmeter is used in parallel around the bulb.

Given that the ammeter measures a current of 3A, we can use Ohm's Law (V = IR) to find the voltage, where V is voltage, I is current, and R is resistance.

By substituting the given values in Ohm's Law:

V = I × R
V = 3A × 40Ω
V = 120V.

Therefore, the voltage of the cell is 120 volts.