ELECTRICITY
In this area, the topics covered are: electrical charge carriers; potential difference (voltage); Ohm’s law; practical electrical
and electronic circuits; electrical power.
and electronic circuits; electrical power.
SUB UNIT HEADING |
DETAILS |
Electrical charge carriers |
- Definition of electrical current as the electric charge transferred per unit time. - Use of an appropriate relationship to solve problems involving charge, current and time. Q = It - Knowledge of the difference between alternating and direct current. - Identification of a source (as a.c. or d.c.) based on oscilloscope trace or image from data logging software. |
Potential difference (voltage) |
- Knowledge that a charged particle experiences a force in an electric field. - Knowledge of the path a charged particle follows: between two oppositely charged parallel plates; near a single point charge; between two oppositely charged points; between two like charged points. - Knowledge that the potential difference (voltage) of the supply is a measure of the energy given to the charge carriers in a circuit. |
Ohm’s law |
- Calculation of the gradient of the line of best fit on a V/I graph to determine resistance. - Use of appropriate relationships to solve problems involving potential difference (voltage), current and resistance. V = IR V2 = (R2/(R1+R2))Vs V1/V2 = R1/R2 - Knowledge of the qualitative relationship between the temperature and resistance of a conductor. - Description of an experiment to verify Ohm’s law. |
Practical electrical and electronic circuits |
- Measurement of current, potential difference (voltage) and resistance, using appropriate meters in simple and complex circuits. - Knowledge of the circuit symbol, function and application of standard electrical and electronic components: cell, battery, lamp, switch, resistor, voltmeter, ammeter, LED, motor, microphone, loudspeaker, photovoltaic cell, fuse, diode, capacitor, thermistor, LDR, relay, transistor. - For transistors, knowledge of the symbols for an npn transistor and an n-channel enhancement mode MOSFET. Explanation of their function as a switch in transistor switching circuits. - Application of the rules for current and potential difference (voltage) in series and parallel circuits. Is = I1 = I2 = ... Vs = V1 + V2 + ... Ip = I1 + I2 + ... Vs = V1 = V2 = ... - Knowledge of the effect on the total resistance of a circuit of adding further resistance in series or in parallel. - Use of appropriate relationships to solve problems involving the total resistance of resistors in series and in parallel circuits, and in circuits with a combination of series and parallel resistors. Rt = R1 + R2 + ... 1/Rt = 1/R1 + 1/R2 + ... |
Electrical power |
- Definition of electrical power in terms of electrical energy and time. - Use of an appropriate relationship to solve problems involving energy, power and time. E = Pt - Knowledge of the effect of potential difference (voltage) and resistance on the current in and power developed across components in a circuit. - Use of appropriate relationships to solve problems involving power, potential difference (voltage), current and resistance in electrical circuits. P = IV P = I^2 R P = V^2/ R - Selection of an appropriate fuse rating given the power rating of an electrical appliance. A 3 A fuse should be selected for most appliances rated up to 720 W, a 13 A fuse for appliances rated over 720 W. |
Summary Notes & Questions
Remember to continual check your past paper attempts and review unknown areas with your summary notes. Websites like BBC Bitesize and Mr MacKenzie Fizzics will also help your revision. Ask your teacher if you are unsure of how to proceed with your revision plan and to clarify areas you are unsure about.