JAMB - Physics (1989 - No. 11)
An electric heater is used to melt a block of ice of mass 1.5kg. If the heater is powered by a 12V battery and a current of 20A flows through the coil, calculate the time taken to melt the block of ice at 0oC. [specific latent heat of fusion of ice = 336 x 103Jkg-1]
76.0min
35.0min
21.0min
2.9min
설명
Elect. energy = heat energy
IVt = mL
20 X 12 t = 1.5 x 336 x 103
t = 2100 sec ; t = 35mins.
IVt = mL
20 X 12 t = 1.5 x 336 x 103
t = 2100 sec ; t = 35mins.