An electric circuit consists of a battery, a variable resistor and connecting wires. Sections PQ and QR of the connecting wire are in a region of space where there is a uniform magnetic field. In Fig. 7.1, the shaded area represents the magnetic field. [Figure 7.1] The direction of the magnetic field is into the page. A current-carrying wire in a magnetic field can experience a force.

1. (a)In the table, mark one tick (✔) in each column to indicate the force on PQ and the force on QR. section PQ section QR no force on this section a force towards the top of the page a force towards the bottom of the page a force out of the page a force into the page a force towards the left of the page a force towards the right of the page[2]
2. (b)The battery in the circuit in Fig. 7.1 is reversed. State and explain the effect of this on PQ and QR.[2]
3. (c)The variable resistor is adjusted and the current in the circuit decreases. Suggest one effect of decreasing the current.[1]

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