SL IB Physics Current & Circuits Flashcards

A Comprehensive collection of vocabulary flashcards covering circuit components, electrical quantities, formulas, and power sources based on SL IB Physics notes.

Cell

A device which converts energy from a chemical energy store to an electrical energy store.

Battery

A power source made up of multiple cells arranged together.

Switch

A device which turns the circuit on (closed) or off (open) to allow or prevent the flow of current.

Voltmeter

A device used to measure the potential difference between two points in a circuit, connected in parallel.

Ammeter

A device used to measure the current flowing in a circuit, connected in series.

High-resistance wire (Fixed Resistor)

A device that increases resistance to limit the flow of current, transforming electric potential energy into other stores like thermal energy.

Variable Resistor

A resistor with a slider that can be used to change its resistance; as resistance increases, the current in the circuit decreases.

Light-dependent resistor (LDR)

A resistor whose resistance decreases as light intensity increases and vice versa.

Thermistor

A resistor whose resistance depends on temperature; for negative temperature coefficient components, resistance decreases as temperature increases.

Potentiometer

A resistor with a sliding contact used to form an adjustable voltage divider.

Light-emitting diode (LED)

A device that emits light when current passes through it and only allows current to flow in one direction.

Earth (ground)

A connection to the Earth that allows an instantaneous discharge to occur through a low-resistance wire if an appliance malfunctions.

Ideal Ammeter

An ammeter with zero resistance so that it does not take energy from the electrons or alter the current it is measuring.

Ideal Voltmeter

A voltmeter with infinite resistance such that no current passes through it.

Electric Current

The rate of flow of charge carriers, measured in amperes ($A$). It is calculated using $I = \frac{\triangle q}{\triangle t}$.

Conventional Current

The flow of positive charge from the positive terminal of a cell to the negative terminal.

Direct Current (dc)

Current that only flows in one direction and maintains a single value.

Electric Potential Difference (p.d.)

The work done per unit charge on moving a positive charge between two points along the path of the current ($V = \frac{W}{q}$).

Volt (V)

The unit of potential difference, where $1\,V$ is equivalent to $1\,Joule$ per Coulomb ($1\,V = 1\,J\,C^{-1}$).

Electronvolt (eV)

The amount of energy needed to move an electron through a potential difference of one volt ($1\,eV = 1.6 \times 10^{-19}\,J$).

Conductor

A material, usually a metal, that allows charge to flow through it easily due to a sea of delocalised electrons.

Insulator

A material that has no free charges and does not allow the flow of charge through it easily.

Electric Resistance (R)

The ratio of the potential difference across a component to the current flowing through it ($R = \frac{V}{I}$), measured in ohms ($\Omega$).

Resistivity ($\rho$)

A property of a material representing the resistance per unit length of a material with unit cross-sectional area ($\rho = \frac{RA}{L}$).

Ohm's Law

States that for a component at a constant temperature, the current through it is proportional to the potential difference across it ($V = IR$).

Forward-biased

A condition in a diode where current flows when the potential difference is applied in the direction of the arrowhead symbol.

Reverse-biased

A condition in a diode where it does not conduct current because it is switched around.

Resistors in Series

Components where the combined resistance is the sum of individual resistances: $R = R_1 + R_2 + R_3$.

Resistors in Parallel

Components where the reciprocal of the combined resistance is the sum of the reciprocals of individual resistances: $\frac{1}{R} = \frac{1}{R_1} + \frac{1}{R_2}$.

Electrical Power (P)

The rate of change of work done, calculated as $P = IV$ or $P = I^2R$ or $P = \frac{V^2}{R}$, measured in Watts ($W$).

Electromotive Force (e.m.f.)

The amount of chemical energy converted to electrical energy per coulomb of charge when charge passes through a power supply.

Internal Resistance (r)

Resistance inside a power supply between its terminals that causes loss of voltage and heating of the cell.

Lost Volts

The potential difference 'lost' due to the internal resistance in the cell, calculated as $V = Ir$.