Question 1

The objective of this question is to work out the unknown resistance \( R \).

We have the following information:

  • the current flow through the circuit (1 A); and
  • the driving source voltage of the circuit (5 V).


This circuit may be solved using Ohm's Law:

\( R = \frac{V_{\mathrm{s}}}{I} = \frac{5}{1} = 5 \) i.e. \( R \) = 5 Ω #.


Question 2


The objective of this question is to work out the unknown current \( I \).

We have the following information:

  • the resistance of the circuit (10 Ω); and
  • the voltage applied to the circuit (2 V).


This circuit may be solved using Ohm's Law:

\( I = \frac{V}{R} = \frac{2}{10} \) i.e. \( I \) = 0.2 A #.


Question 3


Question 3 is similar to Question 2.

The objective of this question is to work out the unknown current \( I \).

We have the following information:

  • the resistance of the circuit (27 Ω); and
  • the voltage applied to the circuit (9 V).


This circuit may be solved using Ohm's Law:

\( I = \frac{V}{R} = \frac{3}{9} \) i.e. \( I \) = 0.333 A (to 3 sf) #.


Question 4


The objective of this question is to work out the unknown voltage \( V \).

We have the following information:

  • the resistance of the circuit (12 Ω); and
  • the current flow in the (5 A).


This circuit may be solved using Ohm's Law:

\( V = IR = 5 \cdot 12 \) i.e. \( V \) = 60 V #.


Question 5


The objective of this question is to work out the unknown supply voltage \( V \), similarly to Question 1.

We have the following information:

  • the current flow through the circuit (5 A); and
  • the total resistance of the circuit (2 Ω).


This circuit may be solved using Ohm's Law:

\( V_{\mathrm{s}} = IR = 5 \cdot 2 = 10 \) i.e. \( V_{\mathrm{s}}\) = 10 V #.

Question 6


No applicable answer.


Question 7


The objective of this question is to work out the unknown current \( I \), given the circuit as shown.

We have the following information:

  • the circuit has two 5 Ω resistors in series; and
  • the voltage applied to the circuit is 10 V.


This circuit may be solved using two rules:

  • Series resistance; and
  • Ohm's Law.

The series resistance formula gives us a total resistance (\( R_{\mathrm{TOT}} \)) of \( 5 + 5 \) = 10 Ω.

\( I = \frac{V}{ R_{\mathrm{TOT}}} = \frac{10}{10} \) i.e. \( I \) = 1 A #.


Question 8


The objective of this question is to work out the unknown current \( I \), given the circuit as shown.

We have the following information:

  • the circuit has a 10 Ω resistor and a 37 Ω resistor in series; and
  • the voltage applied to the circuit is 10 V.


This circuit may be solved using two rules:

  • Series resistance; and
  • Ohm's Law.

The series resistance formula gives us a total resistance (\( R_{\mathrm{TOT}} \)) of \( 10 + 37 \) = 47 Ω.

\( I = \frac{V}{ R_{\mathrm{TOT}}} = \frac{10}{47} \) i.e. \( I \) = 0.213 A (to 3 sf) #.


Question 9


The objective of this question is to work out the unknown current \( I \), given the circuit as shown.

We have the following information:

  • the circuit has the following series resistors: 2 Ω, 7 Ω, 5 Ω, 4 Ω, and 8 Ω; and
  • the voltage applied to the circuit is 50 V.


This circuit may be solved using two rules:

  • Series resistance; and
  • Ohm's Law.

The series resistance formula gives us a total resistance (\( R_{\mathrm{TOT}} \)) of \( 2 + 7 + 5 + 4 + 8 \) = 26 Ω.

\( I = \frac{V}{ R_{\mathrm{TOT}}} = \frac{50}{26} \) i.e. \( I \) = 1.92 A (to 3 sf) #.


Question 10


This answers to the question are as shown below. All the currents shown on this worksheet are conventional current. They are conventional current because all currents in circuits are assumed conventional unless otherwise stated.


Last modified: Thursday, 7 May 2020, 10:43 AM