Electromagnetic Induction - AP Physics C: Electricity and Magnetism

Reverses current direction, maintaining output polarity. Mechanical switching device that converts AC to pulsed DC.

An electromotive force (EMF). Changing magnetic flux creates electric field and drives current.

EMF is induced to oppose the increase. Lenz's law - EMF opposes the flux increase.

Right-hand rule. Determines direction of induced current from flux change direction.

$\text{EMF} = -2 \text{V}$. EMF = $-100 \times 0.02 = -2$ V from Faraday's law.

$E = 9 \text{J}$. Using $E = \frac{1}{2} \times 2 \times 3^2 = 9$ J.

$\text{Φ}_B \text{approx. } 3.18 \text{Wb}$. $1.5 \times 3 \times \cos(45°) = 1.5 \times 3 \times 0.707 ≈ 3.18$ Wb.

$\text{Φ}_B = B \times A \times \text{cos}(\theta)$. Product of magnetic field, area, and cosine of angle between them.

Rotation of coil in magnetic field. Rotating coil changes flux continuously, creating sinusoidal EMF.

$\text{EMF} = 4 \text{V}$. Motional EMF: $0.8 \times 1 \times 5 \times \sin(90°) = 4$ V.

To reduce eddy currents. Thin insulated sheets reduce circulating currents and energy loss.

$\text{EMF} = B \times l \times v \times \text{sin}(\theta)$. Motional EMF from conductor moving through magnetic field.

$\text{Φ}_B = B \times A \times \text{cos}(\theta)$. Product of magnetic field, area, and cosine of angle between them.

$\text{EMF} = -10 \text{V}$. $\frac{d\text{Φ}_B}{dt} = \frac{0.5 \times 2}{0.1} = 10$, so EMF = $-10$ V.

The relative orientation of the coils. Geometric arrangement determines magnetic coupling strength between coils.

$\text{EMF} = -80 \text{V}$. $\frac{d\text{Φ}_B}{dt} = \frac{2 \times 4}{0.1} = 80$, so EMF = $-80$ V.

Increased induced voltage. More turns in secondary winding increases output voltage.

Henry (H). Named after Joseph Henry, measures opposition to current change.

Induction of EMF in one coil due to changing current in another. Changing current in one coil affects nearby coil's flux.

EMF is zero; no change in flux. No flux change means no induced EMF by Faraday's law.

Volt (V). Standard unit for electrical potential difference and EMF.

Induced EMF is proportional to the number of turns. More turns means more flux linkages and greater total EMF.

Magnetic flux in the core. Alternating primary current creates changing flux in core.

Speed of rotation and magnetic field strength. Both factors determine the rate of flux change.

The core. Iron core provides magnetic coupling while electrically isolating windings.

Induced EMF opposes the change in magnetic flux. Conservation of energy principle - induced effects oppose their cause.

$\text{Φ}_B = 1.2 \text{Wb}$. $0.6 \times 2 \times \cos(0°) = 1.2$ Wb using flux formula.

Using laminated cores. Prevents eddy currents that waste energy as heat.

Induced EMF is proportional to flux change. Faraday's law establishes this direct proportional relationship.