Home Practice
For learners and parents For teachers and schools
Full catalogue
Learners Leaderboard Classes/Grades Leaderboard Schools Leaderboard
Pricing Support
Help centre Contact us
Log in

We think you are located in United States. Is this correct?

11.4 Chapter summary

11.4 Chapter summary (ESBQH)

temp text

Presentation: 243S

  • Ohm's Law states that the amount of current through a conductor, at constant temperature, is proportional to the voltage across the resistor. Mathematically we write \(I = \frac{V}{R}\)

  • Conductors that obey Ohm's Law are called ohmic conductors; those that do not are called non-ohmic conductors.

  • We use Ohm's Law to calculate the resistance of a resistor. \(R = \frac{V}{I}\)

  • The equivalent resistance of resistors in series (\(R_{s}\)) can be calculated as follows: \(R_{s} = R_{1} + R_{2} + R_{3} + \ldots + R_{n}\)

  • The equivalent resistance of resistors in parallel (\(R_{p}\)) can be calculated as follows: \(\frac{1}{R_{p}} = \frac{1}{R_{1}} + \frac{1}{R_{2}} + \frac{1}{R_{3}} + \ldots + \frac{1}{R_{n}}\)

  • Electrical power is the rate at which electrical energy is converted in an electric circuit.

  • The electrical power dissipated in a circuit element or device is \(P=VI\) and can also be written as \(P=I^2R\) or \(P=\frac{V^2}{R}\) and is measured in joules (J).

  • The electrical energy dissipated is \(E=Pt\) and is measured in joules (J).

  • One kilowatt hour refers to the use of one kilowatt of power for one hour.

Physical Quantities
Quantity Unit name Unit symbol
Current (\(I\)) Amperes \(\text{A}\)
Electrical energy (\(E\)) Joules \(\text{J}\)
Power (\(P\)) Watts \(\text{W}\)
Resistance (\(R\)) Ohms \(\text{Ω}\)
Voltage (\(V\)) Volts \(\text{V}\)

Table 11.1: Units used in electrostatics