ELECTRICITY 1. Figure below shows a circuit with three resistors, a power supply and four voltmeters. a. Calculate the combined resistance of the three resistors. b. Write down two relationships for the currents in the circuit. c. Write down two relationships for the voltmeter readings in the circuit. 2. The circuit of figure below is set up to run a small immersion heater from a 6.0 V battery. a. State the name and purpose of component X. b. The heater is designed to work from a 3.6 V supply. It has a power rating of 4.5 W at this voltage. (i) Calculate the current in the heater when it has the correct potential difference across it. (ii) Calculate the resistance of component X if there is to be the correct potential difference across the heater. The battery and the ammeter both have zero resistance. 3. Look at the diagram. a. Find the p.d across 3 Ω. b. Find the current across 6 Ω. 4. Below is the circuit of electricity. The cell has an internal resistance 0.4 Ω. a. Calculate the p.d across 9 Ω. b. Calculate the p.d across 1 Ω. c. Calculate the current across 6 Ω. 5. Figure below shows a circuit containing a battery, three resistors and an ammeter. a. Calculate the current in the circuit. b. A voltmeter is to be used to measure the potential difference across the resistors in parallel. (i) Draw the voltmeter in position in the circuit, using the correct circuit symbol. (ii) The ammeter reads 1.6 A. Calculate the reading on the voltmeter. 6. Figure below shows a circuit containing a 12 V power supply, some resistors and an ammeter whose resistance is so small that it may be ignored. a. Calculate the p.d across 2 Ω and 4 Ω. b. Calculate the current across 3 Ω.