Question

1.. An alternating current, when passed through a resistor immersed in water for 5 min, just raised the temperature of the water to boiling point. When a direct current of 4 A was passed through the same resistor under identical conditions, it took 8 min to boil the water. Find the r.m.s. value of the alternating current. Neglect factors other than heat given to the water. If a rectifier type of ammeter connected in series with the resistor read 5.2 A when the alternating current was flowing, find the form factor of the alternating current

An alternating current i is represented by i = 10sin942t amperes. Determine: (a) the frequency; (b) the period; (c) the time taken from t = 0 for the current to reach a value of 6 A for a first and second time; (d) the energy dissipated when the current flows through a 20 Ω resistor for 30 min.

Answer 1