Question

Find the no. of electrons which constitute a current of 2A. If a potential difference of 13V was applied across a wire, how much work was done on the electrons??​

Answer 1

Given :

Current flow = 2A

Potential difference across the wire = 13V

To Find :

Number of electrons flowing in the wire and work done on the electrons.

Solution :

■ In order to find number of electrons flowing in the wire, first of all we need to find net charge flow in the wire.

• We know that, current is defined as the rate of charge flow per unit time.
• Mathematically, I = Q/t

By substituting the given values;

➠ I = Q/t

➠ 2 = Q/1

➠ Q = 2 C

As per law of charge quantization :

➨ Q = n × e

• n denotes number of electrons
• e denotes charge of electron

➨ 2 = n × (1.6 × $\sf10^{-19}$)

➨ n = 2/1.6 × 10¹⁹

➨ n = 1.25 × 10¹⁹ electrons

■ Work done in moving a charge of magnitude q from one point to another point having potential difference V is given by, W = q × V

➙ W = q × V

➙ W = 2 × 13

➙ W = 26 J