*This activity is spread over two sessions. 4.2.1.4 How the The resistance of 1.5 Draw the I-V graphs for a Required practical *: resistance of components such as filament lamp and a diode. Use circuit diagrams to electrical filament lamps, diodes, Explain the of the resulting construct appropriate circuits components thermistors and LDRs is not graph in terms of resistance and change with constant; it changes with the to investigate the I–V current. external current through the characteristics of a variety of conditions. component. Draw graphs to show how the circuit elements including a resistance of an LDR will vary filament lamp, a diode and a The resistance of a filament with light intensity and of a lamp increases as the resistor at constant Current-potential thermistor with temperature. temperature of the filament temperature. (8.2.4) difference graphs increases. Why do the current-potential for electrical Plot the graphs for these difference graphs for diodes and components. The current through a diode components and explain the filament lamps look different to flows in one direction only. that of an ohmic conductor? resulting shape in terms or The diode has a very high resistance. resistance in the reverse Calculate the resistance of an direction. LDR or a thermistor the Plan and carry out an range of resistances for that investigation into how the The resistance of a component and the conditions thermistor decreases as the resistance of an LDR varies that it is placed in. temperature increases. with light intensity and how Describe and explain real world the resistance of a thermistor The resistance of an LDR applications of thermistors and varies with temperature. decreases as light intensity LDRs including thermostats and increases. switching on lights.
*This activity is spread over two sessions. 4.2.1.4 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 light intensity increases. 1.5 Draw the I-V graphs for a filament lamp and a diode. Explain the 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 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. (8.2.4) Plot the graphs for these components and explain the resulting shape in terms or resistance. Plan and carry 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-8463-SOW-ELEC.DOCX