Charge and Current - A Level Physics

These flashcards cover essential concepts related to charge and current in physics, including definitions, laws, and formulas.

Electric current, I, is defined as the rate of flow of charge __.

I = dQ/dt

The SI base unit for current is __.

Amperes (A)

Charge, Q, is measured in __.

coulombs (C)

1 coulomb is the flow of charge in a time of 1 second when the current is __.

1 ampere

Like charges __each other, whereas opposite charges __each other.

repel, attract

A proton has a charge of __, and an electron has a charge of __.

+1, -1

The quantised charge value for a particle is represented by __.

the elementary charge, e, which is 1.6 x 10^-19 C

The net charge on a particle Q is given by __.

Q = ±ne

Electrons are the charge carriers in __.

metals

In a metal, the positive metal ions are __, surrounded by free electrons.

fixed in place

The cations are attracted to the electrode, and the anions are attracted to the electrode.

cathode, anode

Conventional current is defined as the rate of flow of charge from the terminal to the terminal.

positive, negative

Kirchhoff’s first law states that the sum of the currents into a point is __ to the sum of the currents coming out of that point.

equal

Charge cannot be created or destroyed; it must be __.

conserved

Mean drift velocity, v, is defined as __.

the average velocity of the electrons as they travel down the wire

The number density, n, represents __ of free electrons per unit volume.

the number

Conductors such as metals have very high number densities, around __ per m3.

10^28

The current, I, can also be expressed as __.

I = nAve

The volume of the wire is equal to its multiplied by its .

cross-sectional area, length

The formula I = nAv can be rearranged to find the __ for electrons in a wire.

mean drift velocity