Exercises: Motors, Generators, and Transformers

Electromagnetic induction — a changing flux induces a current in the coil.

Magnetic force on a current-carrying loop creates a torque that rotates the coil.

The battery pushes current through the coil, and the current itself generates rotation.

Electrostatic attraction between the coil and the magnets causes rotation.

A generator uses a different physical law than a motor — they share no common principle.

A generator converts mechanical rotation to electrical energy via induction; a motor converts electrical energy to mechanical rotation via magnetic force — they are the same device operated in opposite directions.

A generator only produces DC; a motor only runs on AC.

A generator requires permanent magnets; a motor requires electromagnets.

$\frac{V_s}{V_p} = \frac{N_s}{N_p}$

$V_s \cdot N_s = V_p \cdot N_p$

$\frac{V_s}{V_p} = \frac{N_p}{N_s}$

$V_s = V_p + (N_s - N_p)$

To increase the current through the coil and produce more torque.

To prevent the coil from overheating by alternating the current direction.

To ensure the torque always acts in the same rotational direction, maintaining continuous rotation.

To convert AC from the power supply to DC for the coil.

The EMF is constant because the field is uniform.

The EMF varies sinusoidally because the rate of flux change is sinusoidal.

The EMF increases linearly as the coil rotates faster.

The EMF is zero whenever the coil is parallel to the field.