Question

A p.d. of 10 V is needed to make a current of 0.02 A flow through a wire. What p.d. is needed to make a current of 250 mA flow through the same wire?

Answer 1

125 volts is needed to make a current of 250 mA flow through the same wire.

Explanation:

Given:

A p.d. of 10 V is needed to make a current of 0.02 A flow through a wire.

The resistance of wire 'r' is given by

$r = \frac{v}{i}$

$r = \frac{10}{0.02}$

$r = 500 \: ohm$

To make a current of 250 mA i.e. 0.25 A flow through the same wire.

The potential difference is given by

$v = i \times r$

$v = 0.25 \times 500$

$v = 125 \: volts$

125 volts is needed to make a current of 250 mA flow through the same wire.

Answer 2

Potential Difference Needed is 125 V

Explanation:

Here, $I_1 = 0.02$ amp, $V_1$ = 10 volt

V = IR

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

= $\frac {10}{0.02}$

= $500 \Omega$

Again,

$I_2 = 250 mA$

= 0.25 A

R = $500\ \Omega$

$V_2 = I_2R$

= $0.25 \times 500$  

= 125 V