Physics and Magnetism Lecture Notes Review

Flashcards covering principles of magnetism, sound waves, basic wave mechanics, circuit electricity, and electromagnetic induction.

Magnet

Any substance which attracts pieces at Iron towards itself and always comes to rest in N-S direction.

Magnetic Materials

Substances such as iron, nickel, and cobalt that are strongly attracted to magnets and show strong magnetic effects.

Magnetic Domains

Small regions in magnets in which each region acts as a tiny magnet.

Magnetic fields

The region around the magnet where force acts.

Magnetic field lines

Imaginary lines used to represent magnetic fields that travel from north to south outside the magnet and continue from south to north inside to form a closed loop.

Galvanometer

A device to measure small currents.

Electric Motor

A device that converts electricity into mechanical energy.

Temporary magnet

An object that becomes a magnet only while under the influence of another magnet and usually loses its magnetism when the magnet is removed.

Electromagnet

A magnet made by passing electric current through a coil at wire; its strength can be controlled by changing the current or number at turns.

Sound

Produced by vibrations, it is a mechanical wave that needs matter such as air, water, or solids to travel through.

Compressions

A region in sound waves where particles are squeezed closely together, making it a high pressure region.

Rarefactions

A region in sound waves where particles are spread farther apart, making it a low pressure region.

Longitudinal wave

A wave where particles vibrate parallel (back and forth) to the wave's direction, such as sound waves or shock waves.

Pitch / frequency

How high or low a sound is, which depends on the frequency at vibrations per second measured in Hertz ($Hz$).

Wave

A disturbance that transfers energy from one place to another without transferring matter.

Mechanical wave

A wave that needs a medium (matter) to travel through, such as Air, Water, A rope, A spring, or a solid object.

Transverse Wave

A wave where particles at the medium move perpendicular to the direction at wave travel, such as waves on a rope, water waves, or light waves.

Frequency ($f$)

The number at waves produced per second, calculated as $f = \frac{1}{T}$, where $T$ is the period.

Period ($T$)

The time taken to complete one full wave; it is inversely proportional to frequency.

Wavelength ($\lambda$)

The distance between two consecutive crests or two consecutive troughs.

Wave Speed ($v$)

The speed at which a wave travels through a medium, which depends on the medium and type at wave but not on amplitude, frequency, or wavelength.

Rigid Boundary

A fixed end where a wave is reflected and inverted, meaning a crest becomes a trough and a trough becomes a crest.

Loose (free) Boundary

An end that is free to move where the reflected wave is not inverted and keeps its original orientation.

Constructive Interference

Occurs when two waves meet so that a crest meets a crest and a trough meets a trough, creating a wave with a larger amplitude.

Destructive Interference

Occurs when two waves meet so that a crest meets a trough, causing their displacements to subtract and produce a smaller amplitude.

Standing wave

Formed when two waves at the same frequency and amplitude moving in different directions interfere, producing points that appear not to move.

Node

A point in a standing wave where displacement is always zero formed due to complete destructive interference.

Antinode

A point in a standing wave where displacement is maximum.

Refraction

When the speed, wavelength, and direction at a wave change due to a change in medium.

Diffraction

The spreading at waves as they pass a gap (an opening) or around an obstacle.

Current ($I$)

The rate at flow at electric charge through a circuit, measured in Ampere ($A$).

Voltage ($V$)

The energy transferred per unit charge between two points in a circuit, acting as the push that makes charges move, measured in Volt ($V$).

Resistance ($R$)

The opposition to the flow at electric current, measured in ohm ($\Omega$).

Ohm's law

States that the current through a conductor increases as the voltage increases as long as the temperature remains constant ($V = IR$).

Series Circuit

A circuit where the same current flows through all components, voltage is shared, and total resistance increases as resistors are added ($R_{eq} = R_1 + R_2 + R_3...$).

Parallel Circuit

A circuit where current splits between branches, each branch gets full source voltage, and total resistance decreases when branches are added.

Power ($p$)

The rate at which energy is transferred or how fast energy is being used or converted.

Superconductors

A material with zero electrical resistance ($R = 0$) where current flows without opposition and no energy loss occurs.

Induced Current

Electric current produced in a conductor due to a change at magnetic flux, always directed opposite to the change in flux.

Generator

A device or machine that converts mechanical energy into electrical energy.

Electromotive force (EMF)

The voltage supplied by a source at electrical energy, such as a battery, providing energy to the circuit.

Induced EMF

A voltage produced when a conductor experiences a changing magnetic field; it occurs without a battery.

Lenz's law

States that induced current flows in a direction that opposes the change in magnetic flux that produced it.

Eddy Currents

Circular currents induced in a conductor due to a change in magnetic flux.

Transformer

A device used to increase or decrease AC voltage.

Step-up transformer

A transformer that increases voltage ($V_s > V_p$) and has more turns on the secondary coil than the primary.

Step-down transformer

A transformer that decreases voltage ($V_p > V_s$) and has more turns on the primary coil than the secondary.