Questions about circuits with parallel connections

What the Activity is for

These diagnostic questions are used for two main reasons:

• To encourage students to talk and think through their understandings of electric circuits.
• To provide the teacher with formative assessment information about the students' understandings of electric circuits.

What to Prepare

• printed copies of the questions (see below)

What Happens During this Activity

It would be a good idea to get the students to work in pairs on these questions, encouraging each pair to talk through their ideas. Collect responses from all of the pairs and discuss them in a whole-class plenary.

Alternatively, the questions might be set for homework prior to the lesson, so that you have time to read through the responses.

The questions review key points relating to parallel circuits.

Answers to the question sheet listed below:

Question 1

The potential difference across both resistors in a parallel circuit is the same, irrespective of resistance (the current through each resistor is different).

Question 2

This is just the same as question 1.

Question 3

When the switch is closed, the ammeter reading stays the same, as does the bulb brightness. This is because the potential difference across B1 stays the same.

Question 4

A₁ is 2 ampere. A₂ is 1 ampere (current equal in equal arms);

A₃ is 6 ampere and A₄ is 4 ampere (current inversely proportional to resistance. Big resistance, small current);

A₅ is 4 ampere (current inversely proportional to resistance) and A₆ is 5 ampere.