A transformer has an efficiency of 92.5%. the ratio number of turns in the primary coil to that in the secondary coil is 128 : 45. If the current passing through the secondary coil is 9.0A, calculate the current passing through the primary-coil.
An immersion heater is rated 1500W. How long does it take the heater to raise the temperature of 1 kg of water by 30°C? (Assume heat lost to the surrounding is negligible, Specific heat capacity of water 4200Jkg-1K-1)
