Magnetism and the Photoelectric Effect Lecture Preparation

Vocabulary terms and definitions covering magnetic properties, electromagnetic induction devices, and the principles of the photoelectric effect based on the lecture transcript.

Magnetic Field

A region of space surrounding a magnetic material or a moving charge that exerts a force on other moving charges.

Magnetic Domain

A region of a material with aligned electron spin.

Permanent Magnets

Materials where magnetic domains are aligned without an external magnetic field (ex. neodymium).

Ferromagnetic

Materials whose magnetic domains will readily align with external magnetic fields (ex. iron).

Paramagnetic

Materials whose magnetic domains will not align with external magnetic fields (ex. aluminum).

Solenoid

A coil of wire wrapped around a central axis with a very strong magnetic field inside the coil.

Magnetic Flux

The amount of magnetic field that passes through a certain area.

Electromagnetic Induction

The creation of voltage and current in a closed loop of wire due to a change in magnetic flux through the loop.

Lenz’s Law

A principle stating that an induced voltage always gives rise to a current whose magnetic field opposes the original change in magnetic flux; used to determine the direction of induced current.

Photoelectric Effect

The phenomenon where electrons are emitted when light of a certain frequency shines on a piece of metal.

Photon

A particle of light.

Work Function

The minimum amount of energy required for the photoelectric effect to occur.

Light Intensity (Photoelectric Effect)

If increased, more electrons are emitted from the metal.

Light Frequency (Photoelectric Effect)

Determines the energy of a photon; increasing it beyond the threshold results in emitted electrons having more kinetic energy, though the number of electrons stays constant.

Speaker

A device where moving charges create a magnetic field and force on a current-carrying wire, causing a cone to vibrate and emit sound waves.

Microphone

A device where sound waves cause a coil of wire to vibrate in a magnetic field, generating a current (electromagnetic induction).

Transformer

A device using two different sized solenoids and electromagnetic induction to result in a larger or smaller voltage; only works if the input current is AC.

Motor

A device that converts electrical energy to mechanical energy by running current through coils of wire in a magnetic field to cause rotation.

Generator

A device that converts mechanical energy to electrical energy by rotating a coil of wires in a magnetic field to induce a current.

Solar Cell

An application of the photoelectric effect where light from the sun strikes metal, emitting electrons that are collected and stored as electrical energy.