Three resistors Of 5 Ω, 10 Ω and 15 Ω are connected in series with a 12 V power supply.

(a) Calculate their combined resistance and the current that flows in the circuit and in each resistor.

(b) Find the potential difference across each resistor.

(a) What is the reason of spraying of water on the roads in the evening of hot summer?

(b) Explain the benefits of high specific heat capacity of water.

(a) The melting point of naphthalene is 80° C and the room temperature is 25°. A sample of liquid naphthalene at 90° is cooled down to room temperature. Draw a temperature-time graph to represent this cooling. On the graph mark the region which corresponds to the freezing process.

(b) It takes a much longer time to boil off (change to steam) a certain quantity of water rather than bring it to its boiling point from room temperature, say 25°C. Explain the reason for this.

(a) Draw a schematic diagram of main circuit.

(b) Define conductivity.

(c) Of the three connecting wires in a household circuit, which two of the three wires are at the same potential?