Home Practice
For learners and parents For teachers and schools
Textbooks
Full catalogue
Leaderboards
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?

10.6 Chapter summary

10.6 Chapter summary (ESCQ2)

Presentation: 27XW

  1. Ohm's Law governs the relationship between current and potential difference for a circuit element at constant temperature. Mathematically we write \(I=\frac{V}{R}\).

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

  3. Ohm's Law can be applied to a single circuit element or the circuit as a whole (if the components are ohmic).

  4. The equivalent resistance of resistors in series (\({R}_{s}\)) can be calculated as follows: \({R}_{s}={R}_{\text{1}}+{R}_{\text{2}}+{R}_{\text{3}}+...+{R}_{n}\)

  5. The equivalent resistance of resistors in parallel (\({R}_{p}\)) can be calculated as follows: \(\frac{\text{1}}{{R}_{p}}=\frac{\text{1}}{{R}_{\text{1}}}+\frac{\text{1}}{{R}_{\text{2}}}+\frac{\text{1}}{{R}_{\text{3}}}+...+\frac{\text{1}}{{R}_{n}}\)

  6. Real batteries have an internal resistance.

  7. The potential difference \(V\) of the battery is related to its emf \(\mathcal{E}\) and internal resistance \(r\) by:

    \begin{align*} \mathcal{E}& = V_{\text{load}} + V_{\text{internal resistance}}\\ &\text{or} \\ \mathcal{E}& = IR_{Ext} + Ir \end{align*}
  8. The external resistance in the circuit is referred to as the load.

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 / Potential difference (\(V\)) Volts \(\text{V}\)

Table 10.1: Units used in electric circuits

temp text