Question

An electric kettle working on a 220v mains draws a current of 1.4 amp .If the efficiency of the kettle is 70% find the mass of water whose temperature can be raised from 20° C to 100°C by the kettle in 20 minutes

Answer 1

Answer:

772.57 g

Explanation:

Heat generated by the kettle=

VIt=220*1.4*20*60=369.6kJ

Output heat=70%*369.6=258.72kJ

Let mass be m grams

We know

Q=Sm*(change in temperature)

258720=4.186*m*80

m= 772.57g (approx)