Electricity and Magnetism Flashcards

Flashcards on Electricity and Magnetism for Grade 11 Physics.

The energy provided by a source per coulomb of charge; a type of voltage that drives current.

Electromotive Force (EMF)

Maximum potential difference when no current flows.

EMF

Battery with no internal resistance; voltage across terminals equals EMF.

Ideal Battery

Battery with internal resistance; terminal voltage drops when current flows.

Real Battery

The actual voltage available to the external circuit.

Terminal Voltage

V = ε − Ir

Terminal Voltage Formula

Each resistor adds more opposition to the flow of current, total resistance is the sum of individual resistances.

Total Resistance in Series

A single path for current; same current flows through all resistors; total resistance increases with each resistor added.

Series Circuit

Ensures the same current flows through all components; simple design for current sensors.

Why Use Series Circuits?

If one component fails, the entire circuit breaks; voltage is divided; each device gets less voltage as more are added.

Drawbacks of Series Circuits

Multiple paths for current to flow; each resistor is connected directly across the power source; all resistors share the same voltage.

Parallel Circuit

Each branch is connected directly to the battery, so each resistor gets the same voltage.

Voltage in Parallel

Total current splits among the branches; the branch with the smallest resistance gets the most current.

Current in Parallel

Multiple paths for current; same voltage across all branches.

Parallel Circuit Key Idea

1/Req = 1/R1 + 1/R2 + 1/R3 + …

Total Resistance (Parallel Circuits)

Same across all resistors: Vn = Vbattery.

Voltage (Parallel Circuits)

Splits among branches: I = I1 + I2 + …

Current (Parallel Circuits)

If one component fails, others still work.

Advantage of Parallel Circuits

Total current entering a junction equals the total current leaving the junction; based on conservation of charge.

Junction Rule (Current Law - KCL)

The sum of the potential differences around any closed loop is zero; based on conservation of energy.

Loop Rule (Voltage Law - KVL)

+ε from - to +; −ε from + to -

Sign for Battery (Loop Rule)

−IR if in current direction; +IR if against current

Sign for Resistor (Loop Rule)

Poles: A magnet has two poles, the north and south poles.

Magnetic Poles

Magnets that lose their magnetism once the magnetizing force is removed.

Temporary magnets

Materials that retain their magnetism for a long time after being magnetized.

Hard Magnetic Materials Definition

Materials that easily gain and lose magnetism.

Soft Magnetic Materials Definition

The angle between true north (geographic north) and magnetic north (the direction a compass points).

Magnetic Declination

Groups of atoms whose magnetic moments are aligned in the same direction.

Magnetic Domains

Invisible lines that show the direction and strength of the magnetic field.

Magnetic Field Lines

Use magnetic fields to separate ions based on mass-to-charge ratio.

Mass Spectrometers

Accelerate charged particles using magnetic and electric fields.

Cyclotrons

Randomly oriented; their effects cancel out, so there is no net magnetic field.

Unmagnetized Material

External magnetic field causes domains to align with the field. Aligned domains grow in size.

Magnetizing Field Applied

The magnetic moments of atoms are aligned in the same direction.

Magnetic domains

Materials that strongly align with an external magnetic field and can retain their magnetization even after the field is removed.

Ferromagnetic Materials

Iron, cobalt, nickel

Ferromagnetic Materials Examples

Materials that are weakly attracted to a magnetic field and do not retain magnetism after the field is removed.

Paramagnetic Materials

Materials that are weakly repelled by a magnetic field due to induced magnetic moments in the opposite direction.

Diamagnetic Materials