Your electric jug element produces 1.5kW of power. What is the minimum time it will take to heat 1.5L of water from 20 degrees Celcius to boiling
heat=power*time
mc*deltaTemp=power*time
1.5kg*c*80C=1.5j/hr*timeinhours
so you need c in Joules/kgC
and solve for time in hours.