On a bench beneath three electromagnets are three separate piles of small nails, P, Q and R. One group of nails is copper, another is soft iron and the third is steel. Diagram 1 illustrates what happens when the electromagnets are switched on. Diagram 2 illustrates what happens after the electromagnets are switched off. Which row correctly names the materials from which the nails are made?
- Acopper: P; soft iron: Q; steel: R
- Bcopper: P; soft iron: R; steel: Q
- Ccopper: Q; soft iron: P; steel: R
- Dcopper: Q; soft iron: R; steel: P