Find the current (in mA) flowing through a wire of resistance 25 kΩ when a potential difference of 12.5 V is applied across it.

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Question

This question was previously asked in

RRB ALP Fitter 21 Jan 2019 Official Paper (Shift 2)

Answer 1

CONCEPT:

Ohm’s law: At constant temperature and other physical quantities, the potential difference across a current-carrying wire is directly proportional to the current flowing through it.

V= RI

Where V is the potential difference, R is resistance and I is current.

EXPLANATION:

Given that:

Resistance (R) = 25 kΩ = 25 × 10³Ω.

Potential difference (V) = 12.5 V.

Using Ohm's law:

V = R I

I = \(V\over R\)

Substitute above values:

I =\(12.5\over25\times10^3\)\(=0.5\times10^{(-3)} A\)

Current (I) = 0.5 mA.

The electric current flowing through the wire is 0.5 mA. So option 1 is correct.