4. The inductance of an iron-core coil decreases if
A. the iron core is removed
B. the length of the coil decreases
C. the number of turns is decreased
D. none of the above
4. The inductance of an iron-core coil decreases if
A. the iron core is removed
B. the length of the coil decreases
C. the number of turns is decreased
D. none of the above