Module 4.3 - Electricity: Electrical Circuits

Question 1

What is Kirchhoff’s First Law?

Answer 1

The sum of the currents entering a junction in a circuit is equal to the sum of the currents leaving the junction
Consequence of the conservation of charge

Question 2

What is Kirchhoff’s Second Law?

Answer 2

In any closed loop, the sum of the e.m.f. is equal to the sum of the products of the current and resistance (potential difference)
Consequence of the conservation of energy

Question 3

Points about series circuits using Ohm’s Law

Answer 3

Current has the same value at any point in the circuit
The e.m.f. of the cell is equal to the sum of the potential differences across the resistors
The total resistance of the circuit is equal to the sum of the individual resistors

Question 4

Voltage rule for parallel circuits

Answer 4

The components in each branch of a parallel circuit share the same voltage as the cell

Question 5

Current rule for parallel circuits

Answer 5

The total current in a parallel circuit is the sum of the individual branch currents

Question 6

Define potential divider circuit

Answer 6

Uses two resistors in series to split or divide the voltage of the supply in a chosen ratio so that a chosen voltage can be provided to another device or circuit

Question 7

Define the terminal p.d.

Answer 7

The potential difference recorded across the terminals of a cell

Question 8

Define lost volts

Answer 8

The difference between the e.m.f. and the terminal p.d. when charge flows in the cell

Question 9

Define internal resistance

Answer 9

The resistance to electric current of the materials inside (chemicals, wires or components)