**Q2: **

The graph shows the potential difference against time for three current sources.

Which two current sources have a potential difference with a magnitude that is always nonnegative?

- A(b) and (c)
- B(a) and (c)
- C(a) and (b)

Which current source has a potential difference that is constant over time?

- A(a)
- B(c)
- C(b)

What is the peak voltage of source (c)?

What is the peak voltage of source (b)?

Which of the current sources shown in the graph is most likely to be produced by a dynamo containing a commutator?

- A(b)
- B(c)
- C(a)

**Q3: **

The diagram shows four graphs of potential difference against time.

What type of current is produced by these four varying potential differences?

- ARectified alternating current
- BDirect current
- CPulsating current
- DAlternating current

Which graph shows a varying potential difference with the greatest frequency?

- A(d)
- B(b)
- C(a)
- D(c)

What is the peak voltage of graph (c)?

Which graph shows the varying potential difference with the lowest frequency?

- A(d)
- B(c)
- C(a)
- D(b)

What is the peak voltage of graph (d)?