Physics Β· Unit 1 Β· Electrical circuits Β· Current, potential difference and energy flow
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A portable electric heater operates at 240 V and draws a current of 8.5 A. The heater is used continuously for 2.5 hours to warm a workshop. Calculate the total energy transferred by the heater during this time. Show your working.
A crane lifts a steel beam of mass 850 kg vertically upward at a constant velocity. The beam is raised through a height of 12 m in 45 seconds. (Use $g = 10 \text{ m/s}^2$.) (a) Calculate the work done by the crane on the beam. [1] (b) Hence, calculate the power output of the crane in watts. [1] (c) Express the power output in kilowatts. [1]
A technician tests three light-emitting diode (LED) globes by running each for different time intervals and measuring the electrical energy consumed. The results are shown in the table below. Determine which globe has the highest power rating. Show your working.
A kettle transfers 180,000 J of energy in 90 s. What is the power rating of the kettle?