High School

A 6 V battery is connected to the terminals of a 3 m long wire of uniform thickness and resistance of 100 ohms along with another 100 ohm resistor in series. The difference of potentials between points on the wire separated by a distance of 50 cm will be:

(1) 2 V
(2) 3 V
(3) 1 V
(4) 0.5 V

Answer :

To find the potential difference between two points on the wire separated by 50 cm, let's follow these steps:

Firstly, understand that the circuit consists of a 6 V battery, a 3 m long wire with 100 ohms resistance, and another 100 ohm resistor in series.

  1. Total resistance in the circuit:

    The total resistance of the circuit is the sum of the resistance of the wire and the additional resistor:

    [tex]R_{total} = 100 \,\Omega + 100 \,\Omega = 200 \,\Omega[/tex]

  2. Current in the circuit:

    Using Ohm's law, we find the current [tex]I[/tex] in the circuit:

    [tex]V = IR \quad \Rightarrow \quad I = \frac{V}{R_{total}}[/tex]

    [tex]I = \frac{6 \, V}{200 \,\Omega} = 0.03 \, A[/tex]

  3. Potential drop along the wire:

    The potential drop [tex]V_{wire}[/tex] across the entire wire (3 m) is calculated using:

    [tex]V_{wire} = I \times R_{wire} = 0.03 \, A \times 100 \, \Omega = 3 \, V[/tex]

  4. Potential drop for 50 cm of the wire:

    Since the potential drop is uniform along the wire, we calculate the potential difference across 50 cm (or 0.5 m) using proportion:

    [tex]\frac{V_{0.5m}}{V_{wire}} = \frac{0.5}{3} \quad \Rightarrow \quad V_{0.5m} = \frac{0.5}{3} \times 3 \, V = 0.5 \, V[/tex]

Therefore, the potential difference between points on the wire separated by a distance of 50 cm is 0.5 V.

The correct multiple-choice option is (4) 0.5 V.