11 A coil of wire is connected into a circuit containing a variable resistor and a battery. The variable resistor is adjusted until the potential difference across the coil is 1.8 V. In this condition, the current in the circuit is 0.45 A. Calculate the resistance of the coil, resistance = the thermal energy released from this coil in 9 minutes. energy released = The coil in part is replaced by one made of wire which has half the diameter of that in . When the potential difference across the coil is again adjusted to 1.8 V, the current is only 0.30 A. Calculate how the length of wire in the second coil compares with the length of wire in the first coil. length of wire in second coil is ………………………… the length of wire in first coil 0625_s10_qp_31 THEORY 2010 Paper 3, Variant 1 View
An electric kettle contains water at a temperature of 19 °C. The kettle has a power rating of 3.0 kW and is switched on for 3.5 minutes. Calculate the energy supplied to the kettle by the electricity supply. electrical energy = At 3.5 minutes, the temperature of the water reaches 100 °C. The volume of the water in the kettle is 1700 cm3 and its density is 1.0 g / cm3. The specific heat capacity of water is 4200 J / (kg °C). Calculate the thermal energy gained by the water. thermal energy = Calculate the efficiency of the kettle. efficiency = 0625_w19_qp_43 THEORY 2019 Paper 4, Variant 3 View