Think of some other similar uses in control circuits. The potentiometer will also be used for measuring displacement. 4: Using a thermistor 1. You need a thermistor and 150 k resistor in series as a potential divider across the power supply. Connect the multimeter across the thermistor. Note the voltmeter reading. Use the hairdryer to warm up the thermistor gently. Note the new voltmeter reading and the warming time used. 2. Change the resistor to 100 k. Allow the thermistor time to cool down. Repeat step 1. Warm the thermistor with the hairdryer for the same time. Explain why changing the resistor alters the result. What must happen to the pd across the resistor as the thermistor warms up? Using a light dependent resistor (LDR) 1. You need a LDR and 100 k resistor as a potential divider across the power supply. Connect the multimeter across the resistor. Note the voltmeter readings when (i) the lamp is placed close to the LDR, (ii) the lamp is off and (iii) the LDR is covered up. 2. Change the resistor for one of lower value and repeat. What is the effect of changing the resistor value? Try controlling logic devices Electronic switches such as the transistor and logic gates are digital devices. They are 'off' below a threshold voltage (often 0.6 V) and 'on' above that voltage. Changing the resistor value in the potential divider allows you to set the conditions that 'turn on' the device. External references This activity is adapted from Advancing Physics Chapter 2, 200E A series circuit is connected as shown in the diagram. 1. What is the potential difference between A and B? 2. An additional resistor of 100 is connected between the 50 and the cells.  resistor What is the potential difference between A and B now? 3. The additional 100 resistor is now connected in parallel with the first 100 resistor.   What is the potential difference between A and B now? 4. A potential divider is made from a 4 k and a 6 k resistor connected in series with
Think of some other similar uses in control circuits. The potentiometer will also be used for measuring displacement. 4: Using a thermistor 1. You need a thermistor and 150 k resistor in series as a potential divider across the power supply. Connect the multimeter across the thermistor. Note the voltmeter reading. Use the hairdryer to warm up the thermistor gently. Note the new voltmeter reading and the warming time used. 2. Change the resistor to 100 k. Allow the thermistor time to cool down. Repeat step 1. Warm the thermistor with the hairdryer for the same time. Explain why changing the resistor alters the result. What must happen to the pd across the resistor as the thermistor warms up? Using a light dependent resistor (LDR) 1. You need a LDR and 100 k resistor as a potential divider across the power supply. Connect the multimeter across the resistor. Note the voltmeter readings when (i) the lamp is placed close to the LDR, (ii) the lamp is off and (iii) the LDR is covered up. 2. Change the resistor for one of lower value and repeat. What is the effect of changing the resistor value? Try controlling logic devices Electronic switches such as the transistor and logic gates are digital devices. They are 'off' below a threshold voltage (often 0.6 V) and 'on' above that voltage. Changing the resistor value in the potential divider allows you to set the conditions that 'turn on' the device. External references This activity is adapted from Advancing Physics Chapter 2, 200E A series circuit is connected as shown in the diagram. 1. What is the potential difference between A and B? 2. An additional resistor of 100  is connected between the 50 resistor and the cells. What is the potential difference between A and B now? 3. The additional 100  resistor is now connected in parallel with the first 100  resistor. What is the potential difference between A and B now? 4. A potential divider is made from a 4 k and a 6 k resistor connected in series with