If we double the radius of a coil keeping the current through it unchanged, then the magnetic field at any point at a large distance from the centre becomes approximately
A. double
B. three times
C. four times
D. one-fourth
Answer:C
If we double the radius of a coil keeping the current through it unchanged, then the magnetic field at any point at a large distance from the centre becomes approximately
A. double B. three times C. four times D. one-fourth