Capacitance

What is capacitance

• Q/V

• Q - size of charge on the plates of the capacitor

• V - potential difference between the plates

• Measured in farad

In a graph of Vmax against charge, what does the area represent

• the energy transferred when charging a capacitor,which is the electric potential energy

• E = 0.5 *VQ

• Or E = 0.5 * Q²/C

What is the time constant

• RC, unit s

Core Practical 11 - charging and discharging a capacitor

• A data logger is used to display and analyze the pd across a capacitor as it charges and discharges through a resistor, but sometimes if the time is too small, then oscilloscope is also used along with the data logger

• The capacitor is charged through the resistor by connecting the switch

• Discharged through same resistor by moving the switch to contact B

• Pd across capacitor is measured by voltage sensor and recorded by data logger, data is analyzed by computer

• A graph of voltage and time should be plotted by the computer.

What does a capacitor do?

• capacitors are used to store charge in a circuit