Paper 1 Magnetic Fields Answers

Q	Answer	Reason
1	B	Magnetic field lines leave north and enter south outside the magnet.
2	B	Closer spacing indicates larger field magnitude.
3	B	Dot means arrow tip coming out.
4	B	Cross means arrow tail going into the page.
5	B	Straight-wire field lines are concentric circles.
6	B	Use right-hand grip rule for fields around currents.
7	A	For a given distance, $B\propto I$.
8	A	More turns add field contributions.
9	B	Long solenoid field is nearly uniform inside.
10	C	Soft iron concentrates magnetic flux.
11	B	Anticlockwise current viewed from an end gives north pole.
12	B	Magnetic field lines do not start/end on isolated poles.
13	A	Uniform field is drawn with parallel equal-spaced lines.
14	B	Fields between same-direction currents partly oppose.
15	B	Compass needle follows local magnetic field.
16	B	Currents/moving charges produce magnetic fields.
17	A	SI unit of magnetic flux density is tesla.
18	B	Arrows indicate magnetic field direction.
19	A	Solenoid field is proportional to current approximately.
20	B	Right-hand grip direction reverses with current.