Question

An ammeter reads a current of 30 A when it is connected across the terminals of a cell of emf 2 V. Neglecting the meter resistance, find the amount of heat (in calories) in cell in 20 seconds.

Answer 1

Here, `I = 30A, V = 2V, t=20s`. Let r be the internal resistance of a cell. Then
`r = epsilon/I = 2.0/30 = 1/15 Omega`
Heat produced in cell, `H = (I^(2)rt)/(J)`
`= ((30)^(2) xx (1//15)xx 20)/4.2 = 285.7` cals