Physics Chapter 2 Electricity circuit symbols resistance current

Physics Chapter 2 – Electricity – circuit symbols, resistance, current and potential difference Draw the symbols for the below components: Cell: Draw a series circuit and include the components: battery, bulb, voltmeter and ammeter: Describe what potential difference is: State the equation to calculate resistance (give units). Battery: Describe the rule for calculating potential difference in a series and parallel circuit. Switch closed: Switched open: Diode: LED: Draw a parallel circuit and include the components: battery, 2 x bulbs, voltmeter, ammeter and variable resistor: Resistor: Calculate the resistance of a car headlamp when the potential difference is 12 V and the current is 3 A. Show your working out and remember units. Describe what resistance is and how this affects a circuit: Variable resistor: State the equation to calculate charge flow(give units). Fuse: Describe how to calculate resistance in a series circuit: LDR: Describe what current is: Thermistor: Calculate the current when 80 C flows in 16 seconds. Show your working out and remember your units. Lamp/bulb: Voltmeter: Ammeter: Describe the rule for calculating current in a series and parallel circuit. Calculate the resistance in the circuit below:

Physics Chapter 2 – Electricity – I-V graphs, LDR, diode and thermistors. Describe what Ohm’s Law is and give an example of an electrical component that follows this. Describe how a thermistor works: Give examples of where we would use thermistors. Describe how a diode works: Give examples of where we would use a diode. Describe how a LDR works: Give examples of where we would use LDR’s. Describe why the I-V graph of a filament bulb does not follow Ohm’s Law. Draw a current – potential difference graph (I-V) for the following components: Potential difference (V) Current (A) Resistor at a constant temperature Thermistor at a high and low temperature Potential difference (V) Current (A) Filament bulb Current (A) Diode

Physics Chapter 2 – Electricity – in the home, transmitting and power Draw a potential difference graph to show D. C. and A. C current. Label the parts of a plug – state the colours of the wires. Explain why the National grid steps-up the potential difference to 400000 V. Potential difference (V) + 0 Explain the role of transformers in the National Grid including the differences between step-up and step-down. - Describe the difference between A. C and D. C current. What is the role of the neutral wire? Write the equations to calculate energy transferred for power and time. Include units. Write the equations to calculate energy transferred for charge flow and potential difference. Include units. Write the equation to calculate power. Include units. Write the equation that links power, current and resistance. Include units. What is the role of the live wire? What is the National Grid? Draw a brief diagram to show the National Grid and give the potential differences at each stage. What is the role of the earth wire? Convert 1 k. W to Watts and 1 hour to seconds.

Physics Chapter 2 – Electricity –maths skill and 2 x required practical. Calculate the energy transferred for an electric oven with a power rating of 2. 5 k. W that is switched on for 45 minutes. Describe a method used to investigate the I-V characteristics for a filament lamp, a diode and a resistor at a constant temperature. Include a diagram of your set up. Describe a method used to investigate how the resistance of a piece of copper wire changes when its length is changed. Include a diagram of your set up. Independent variable – Dependent variable – Control variables - Write a risk assessment for this practical. Include the risk, hazard and control for at least 1 risk. How does the resistance of the wire change with length and explain why. Calculate the potential difference across the device when it transfers a total of 1800 J of energy with a charge of 75 C. Calculate the power of an electric heater that takes a current of 4 A when connected to a 230 V supply. Calculate: a. The current of the lamp when it has power of 36 W when connected to a 12 V supply. a. The resistance of the lamp.