A student investigates the electrical current in a Force-Sensitive Resistor (FSR) under different applied forces using a circuit consisting of a DC power source, the FSR, an ammeter, and a variable resistor.
Explain how a voltmeter should be connected to monitor the voltage across the FSR.
State why it is necessary to keep the voltage across the FSR constant throughout the investigation.
Explain the purpose of including the variable resistor in this circuit.
The student records the current at different applied forces and plots the results on the graph below.
The student decides to use this circuit to make a simple force meter. Since both scales on the graph go up to 50, they label the ammeter scale directly in Newtons (assuming 1 mA corresponds to 1 N).
Give three reasons why this force meter is unlikely to show the correct force. You can refer to both the circuit and the graph to support your answer.
