Using Ohm's law

This activity has nine questions in two sections:

  • section one is about the relationship between current, voltage and resistance according to Ohm's law
  • section two is about using Ohm's law to calculate unknown values.

Note:

  • You can print this page and write you answers onto it.

 

Section 1 – Relationship between current, voltage and resistance

Instructions:

For each question:

  • use the Ohm's law triangle to assist with the following three questions
  • choose the correct answer
  • write down your answer.

 

1. What is the correct formula to calculate current?

  1. I = V ÷ R.
  2. I = R ÷ V.
  3. I = V x R.

 

2. What is the correct formula to calculate voltage?

  1. V = I ÷ R.
  2. V = R ÷ I.
  3. V = I x R.

 

3. What is the correct formula to calculate resistance?

  1. R = I ÷ V.
  2. R = V ÷ I.
  3. R = I x V.

 

Section 2 – Using Ohm's law to calculate unknown values

Instructions:

For each question:

  • use the Ohm's law circuit to assist with the next six questions.
  • choose the correct answer
  • write down your answer.

 

3. Increasing the circuit voltage has what effect on the current flow?

  1. It increases.
  2. It decreases.
  3. It remains the same.

 

4. Increasing the circuit resistance has what effect on the current flow?

  1. It increases.
  2. It decreases.
  3. It remains the same.

 

5. Set the battery voltage to 12V and resistance to 4Ω, note the current flow (3A). Now double the voltage (eg 24V) . What happens to the current flow?

  1. Halves.
  2. Doubles.
  3. It remains the same.

 

6. Set the battery voltage to 12V and resistance to 4Ω, note the current flow (3A). Now halve the voltage (eg 6V) . What happens to the current flow?

  1. Halves.
  2. Doubles.
  3. It remains the same.

 

7. Set the battery voltage to 12V and resistance to 6Ω, note the current flow (2A). Now double the resistance (eg 12Ω) . What happens to the current flow?

  1. Halves.
  2. Doubles.
  3. It remains the same.

 

8. Set the battery voltage to 12V and resistance to 6Ω, note the current flow (2A). Now reduce the resistance by half (eg 3Ω) . What happens to the current flow?

  1. Halves.
  2. Doubles.
  3. It remains the same.

 

If you had trouble answering the questions about Ohm's law, get more information from:

  • Electrical principles section in Resources
  • text books
  • internet sites
  • your trainer.

When you have finished:

  • show your answers to your trainer
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