Physics – 4.5.5 The d.c. motor | e-Consult

The magnetic turning effect on a coil is directly proportional to the number of turns in the coil. This is because each individual loop of wire experiences a magnetic force when a current flows through it in a magnetic field. The magnitude of this force is given by F = BIlsinθ, where B is the magnetic field strength, I is the current, l is the length of the conductor in the field, and θ is the angle between the magnetic field and the direction of the current.

When the number of turns in the coil increases, each loop experiences the magnetic force independently. Therefore, the total magnetic force on the coil is the sum of the forces on all the individual loops. Since the force on each loop is proportional to the number of turns, the total force on the coil is also directly proportional to the number of turns. This results in a larger turning effect.

In simpler terms, more turns mean more forces acting on the coil, leading to a greater overall torque and thus a stronger turning effect.