1, north magnetic force

2. Arrow curve

3. Magnetic fields North and South Pole

4. Strong magnetic pole

5. North and South

6. Get smaller first and then get bigger

7.a (N on the left and S on the right), the north pole of the 4-point small magnetic needle points horizontally to the right;

B (left is n, right is n), and the north pole of the small magnetic needle at the sun point is vertically downward. (Figure omitted)

8、B

9、B

10、A

1 1, sketch

Expansion and improvement

12, magnets do not overlap.

13 、( 1)C

(2) no.

(3) Geomagnetic field

Bian Xiao suggested: