*This activity is spread over two sessions. 6.2.1.4 How the The resistance of 1.5 Draw the I-V graphs for a Required practical *: resistance of components such as filament filament lamp and a diode. Use circuit diagrams to electrical lamps, diodes, thermistors Explain the shape of the resulting construct appropriate circuits components and LDRs is not constant; it graph in terms of resistance and change with changes with the current to investigate the I–V current. external through the component. characteristics of a variety of conditions. Draw graphs to show how the circuit elements including a The resistance of a filament resistance of an LDR will vary filament lamp, a diode and a lamp increases as the with light intensity and of a temperature of the filament resistor at constant Current-potential thermistor with temperature. increases. temperature. (10.2.16) difference graphs Why do the current-potential for electrical The current through a diode Plot the graphs for these difference graphs for diodes and components. flows in one direction only. components and explain the filament lamps look different to The diode has a very high that of an ohmic conductor? resulting shape in terms or resistance in the reverse resistance. direction. Calculate the resistance of an LDR or a thermistor given the Plan and out an The resistance of a range of resistances for that investigation into how the thermistor decreases as the component and the conditions temperature increases. resistance of an LDR varies that it is placed in. with light intensity and how The resistance of an LDR Describe and explain real world the resistance of a thermistor decreases as intensity applications of thermistors and varies with temperature. increases. LDRs including thermostats and switching on lights.
*This activity is spread over two sessions. 6.2.1.4 How the resistance of electrical components change with external conditions. Current-potential difference graphs for electrical components. The resistance of components such as filament lamps, diodes, thermistors and LDRs is not constant; it changes with the current through the component. The resistance of a filament lamp increases as the temperature of the filament increases. The current through a diode flows in one direction only. The diode has a very high resistance in the reverse direction. The resistance of a thermistor decreases as the temperature increases. The resistance of an LDR decreases as intensity increases. 1.5 Draw the I-V graphs for a filament lamp and a diode. Explain the shape of the resulting graph in terms of resistance and current. Draw graphs to show how the resistance of an LDR will vary with light intensity and of a thermistor with temperature. Why do the current-potential difference graphs for diodes and filament lamps look different to that of an ohmic conductor? Calculate the resistance of an LDR or a thermistor given the range of resistances for that component and the conditions that it is placed in. Describe and explain real world applications of thermistors and LDRs including thermostats and switching on lights. Required practical *: Use circuit diagrams to construct appropriate circuits to investigate the I–V characteristics of a variety of circuit elements including a filament lamp, a diode and a resistor at constant temperature. (10.2.16) Plot the graphs for these components and explain the resulting shape in terms or resistance. Plan and out an investigation into how the resistance of an LDR varies with light intensity and how the resistance of a thermistor varies with temperature.
AQA-8464F-SOW-ELEC.DOCX