Capacitors 101

The capacitance of an object is the amount of charge it is able to store per unit

• Resistance of the plates
• Potential difference across the plates
• Current per second supplied to the plates
• Mass per unit volume of the plates

A capacitor is made up of 2 conducting plates separated by

• A different conductor that is more conductive
• An insulator
• A source of EMF
• A different conductor that is less conductive

When charge builds up on a capacitor plate

• Both plates become negatively charged
• Both plates become positively charged
• The plate connected to the +ve terminal of the cell becomes negatively charged
• The plate connected to the -ve terminal of the cell becomes negatively charged

A 200μF capacitor is charged to a potential difference of 6V. How much charge is stored by the capacitor

• 1.2μC
• 1.2mC
• 4.5mC
• 30,000C

• The charging current is constant.
• The energy stored in the capacitor increases uniformly with time.
• The capacitance of the capacitor is constant.
• The power supply used to charge the capacitor had a constant terminal pd.

Initially a capacitor stores 600 µC of charge. When it loses half of this charge, the potential difference (pd) across it decreases by 50 V.What is the capacitance of the capacitor?

• 1.5μF
• 3.0μF
• 6.0μF
• 12.0μf

An uncharged 4.7 nF capacitor is connected to a 2.5 V supply and becomes fully charged.How many electrons are transferred to the negative plate of the capacitor during this charging process?

• 1.2x10^10
• 5.3x10^10
• 7.3x10^10
• 8.9x10^11

What factors affect the capacitance of a capacitor

• Potential difference of circuit and area of plates
• Area of plates and plate seperation
• Potential difference of circuit and resistance of circuit
• Resistance of circuit and plate seperation

What is a value of the permittivity of free space

• 9.00 x 10^9
• 8.85 x 10^-12
• 2.00 x 10^-17
• 1.6 x 10^-19

The relative permittivity of air is

• 0
• 1
• 5
• 100