A42-cm-long solenoid, 1.8 cm in diameter, is to produce a 0.030-t magnetic field at its center. part a if the maximum current is 4.3 a , how many turns must the solenoid have?

The magnetic field at the center of a solenoid (in vacuum) is given by

where
is the magnetic permittivity in vacuum
is the number of turns
is the length of the solenoid
is the current.

Re-arranging the formula and using , we find the number of turns N:

Ais the answer hope this

stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.