A current of 0.2 A flows through a wire whose ends are at a potential difference of 20 V. Calculate —

(i) the resistance of the wire, and

(ii) the heat energy produced in 1 minute.

(a) Given,

Current (I) = 0.2 A

Potential difference (V) = 20 V

From Ohm's law

V = IR

Substituting the values in the formula above, we get,

$20 = 0.2 \times R \\[0.5em] \Rightarrow R = \dfrac{20}{0.2} \\[0.5em] \Rightarrow R = \dfrac{200}{2} \\[0.5em] \Rightarrow R = 100 Ω$

Hence, the resistance of the wire = 100 Ω

(ii) Given,

Time (t) = 60 sec

heat energy produced in 1 minute = ?

From relation,

Heat energy (H) = I²Rt

Substituting the values in the formula above, we get,

H = 0.2² x 100 x 60 = 240 J