In the set up below, the suspended metre rule is in equilibrium balanced by the magnet and the weight shown. The iron core is fixed to the bench:
![PhycF4T1P2Q18b](https://www.easyelimu.com/images/form_4_past_papers/Form_4_term_1_opener_2021/phyc/phyc/PhycF4T1P2Q18b.PNG)
- State and explain the effect on the metre rule when the switch S, is closed.
- What would be the effect of reversing the battery terminals?