Q1. (a) The diagram shows the information plate on an electric kettle. The kettle is plugged into the a.c. mains electricity supply. 230 V 2760 W 50 Hz Use the information from the plate to answer the following questions. (i) What is the frequency of the a.c. mains electricity supply? (ii) What is the power of the electric kettle? (b) To boil the water in the kettle, 2400 coulombs of charge pass through the heating element in 200 seconds. Calculate the current flowing through the heating element and give the unit. Use the correct equation from the Physics Equations Sheet. Choose the unit from the list below. amps volts watts......... Current =... (3) Page 1 of 10
(c) The amount of charge passing through the heating element of an electric kettle depends on the time the kettle is switched on. What pattern links the amount of charge passing through the heating element and the time the kettle is switched on?...... (Total 7 marks) Page 2 of 10
Q2. The data included in the diagrams gives the power of the electrical appliances. TV 160 W Radiant heater 1.0 kw Hairdryer 1100 W Sandwich toaster 1.1 kw Food processor 0.4 kw Table lamp 40 W (a) (i) Which appliance is designed to transform electrical energy to light and sound? (ii) Which two appliances transform energy at the same rate?... and... (b) During one week, the food processor is used for a total of 3 hours. (i) Use the equation in the box to calculate the energy transferred, in kilowatt-hours, by the food processor in 3 hours. energy transferred (kilowatt-hour, kwh) = power (kilowatt, kw) time (hour, h) Energy transferred =... kwh Page 3 of 10
(ii) Electricity costs 15 pence per kilowatt-hour. Use the equation in the box to calculate the cost of using the food processor for 3 hours. total cost = number of kilowatt-hours cost per kilowatt-hour Cost =... pence (c) A homeowner decides to monitor the amount of electrical energy used in his home. He can do this by using an electricity meter or by using a separate electronic device. Electricity meter Records to the nearest kilowatt-hour Electronic device Records to the nearest 1/100th kilowatt-hour (i) Use one word from the box to complete the following sentence. precise reliable valid The reading given by the electronic device is more... than the reading given by the electricity meter. Page 4 of 10
(ii) Monitoring the electrical energy used in a home may help people to save money by encouraging them to use less electricity. Explain why, apart from saving money, it is important for people to use less electricity. (Total 9 marks) Q3. (a) The diagram shows the traces produced on an oscilloscope when it is connected across different electricity supplies. Which of the traces could have been produced by the mains electricity supply?... Give a reason for your answer....... Page 5 of 10
(b) The picture shows two adaptors being used to plug five electrical appliances into the same socket. Explain why it is dangerous to have all five appliances switched on and working at the same time............. (Total 4 marks) Q4. (a) The resistance of a 24 W, 12 V filament lamp depends on the current flowing through the lamp. For currents up to 0.8 A, the resistance has a constant value of 2.5 Ω. (i) Use the equation in the box to calculate the potential difference across the lamp when a current of 0.8 A flows through the lamp. potential difference = current resistance Potential difference =... V Page 6 of 10
(ii) When the potential difference across the lamp is 12 V, the current through the lamp is 2 A. On the axes below, draw a current potential difference graph for the filament lamp over the range of potential difference from 0 to 12 volts. (iii) Why does the resistance of the lamp change when the current through the lamp exceeds 0.8 A? Page 7 of 10
(b) The lamp is now included in a circuit. The circuit is switched on for 2 minutes. During this time, 72 coulombs of charge pass through the lamp. Use the equation in the box to calculate the energy transformed by the lamp while the circuit is switched on. energy transformed = potential difference charge...... Energy transformed =... J (Total 7 marks) Q5. (a) The bar chart shows the power of three different electric hairdryers. (i) Which one of the hairdryers, A, B or C, would transfer the most energy in 5 minutes? Write the correct answer in the box. (ii) A small travel hairdryer has a power of 500 watts. Draw a fourth bar on the bar chart to show the power of the travel hairdryer. Page 8 of 10
(b) A family shares the same hairdryer. The hairdryer has a power of 1.2 kw. The hairdryer is used for a total of 2 hours each week. (i) Calculate how many kilowatt-hours (kwh) of energy the hairdryer transfers in 2 hours. Use the correct equation from the Physics Equations Sheet. Energy transferred =... kwh (ii) Electricity costs 15 pence per kwh. Calculate the cost of using the hairdryer for 2 hours. Cost =... pence (Total 6 marks) Page 9 of 10
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