JAMB - Physics (1982 - No. 24)
A heater marked 50W will evaporate 0.005kg of boiling water in 50 seconds. The specific latent heat of vaporization of water in J/kg is
5.0 x 106
1.0 x 106
2.5 x 106
2.5 x 105
5.0 x 105
Wyjaśnienie
Heat energy = Electrical energy
mL = power x time
0.005 x L = 50 x 50
L = 5 x 105J/kg
mL = power x time
0.005 x L = 50 x 50
L = 5 x 105J/kg