4. Nails can be turned into magnet by
A. coiling å wire around it and letting the electricity flow into it
B. coiling a wire around the dry cells or batteries.
C coiling dry cells or batteries in the wire
D. letting the electricity pass through it

5. How can you increase the strength of an electromagnet?
A. by letting the electricity pass through it
B. by adding more dry cells or batteries
C. by adding the more magnets
D. by adding longer wires​