Question

The time required for 1 kw heater to raise the temperature of 10 litres of water through 10 c is

Answer 1

100°c is the answer of

Answer 2

1 calorie of heat is needed yo rise the temp of 1 ml (cc) of water.

4.2 joules = 1 calorie. and 4.2 watt-sec = 1 joule.

total heat required = 10000X10 =100000 Cal's

!kw heater gives 1000/4.2 = 238.1Cal's per sec

hence time required to heat to l0 l to 10 o c = 100000/238.1 =420 s = 7 minutes