Charge a capacitor to a known voltage using a d
Capacitors - OCR A-Level Physics
- ChargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C). a capacitor to a known voltageThe energyThe capacity to do work. Measured in joules (J). transferred per unit chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C). between two points. Measured in volts (V). Informal term for potential difference. using a d.c. supply, then switch to discharge through a known resistor.
- Use a data loggerAn electronic device that records measurements (e.g. voltage, current) at regular time intervals automatically. connected to a voltmeterAn instrument that measures potential difference. Connected in parallel across the component. Has very high resistance. across the capacitor to record V at regular time intervals.
- Plot V against t to observe the exponential decay curve.
- $Plot \ln$V against t. A straight line confirms exponential decay; the gradient gives -1/RC.
- Systematic errors: internal resistanceThe opposition to currentThe rate of flow of chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C).. Measured in amperes (A). flow. The ratio of potential difference to currentThe rate of flow of charge. Measured in amperes (A).. Measured in ohms (Ω).The resistanceThe opposition to currentThe rate of flow of charge. Measured in amperes (A). flow. The ratio of potential difference to current. Measured in ohms (Ω). within the source of EMFElectromotive force. The energy transferred per unit charge by a source in driving charge around a complete circuit. Measured in volts (V). itself, which causes energyThe capacity to do work. Measured in joules (J). to be dissipated inside the source. of the voltmeterAn instrument that measures potential difference. Connected in parallel across the component. Has very high resistance. provides a parallel discharge path. Use a voltmeterAn instrument that measures potential difference. Connected in parallel across the component. Has very high resistance. with very high resistanceThe opposition to current flow. The ratio of potential difference to current. Measured in ohms (Ω). (or a data logger) to minimise this.
- Repeat with different values of R and C to verify that \$tau = RC$.