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Electrical Current

Revision as of 19:28, 24 February 2019 by NRJC (talk | contribs) (Equation)

Key Stage 2

Meaning

Electrical Current is the amount of electricity flowing through a wire.

About Electrical Current

The bigger the electrical current the brighter a bulb and the louder a buzzer.
If an electrical current goes through an animal it is called an electrical shock.

Key Stage 3

Meaning

An electrical current is a flow of charge.

About Electrical Current

Current is measured using an Ammeter.
The units of current are amperes, which are also called amps (A).
A current in a wire is a flow of electrons which are negatively charged particles.
Conventional Current flows from positive to negative. This is because electricity was discovered before scientists knew about electrons.
In a salt solution current is the flow of both positive and negative ions.

Key Stage 4

Meaning

Electrical current is the rate of flow of charge.

About Electrical Current

Current is measured using an Ammeter.
The SI Units of current are amperes, which are also called amps (A).
A current in a wire is a flow of electrons which are negatively charged particles.
Conventional Current flows from positive to negative. This is because electricity was discovered before scientists knew about electrons.
In a salt solution current is the flow of both positive and negative ions.
In a series circuit the current is the same everywhere in the circuit.
In a parallel circuit the current splits at a junction.

Equation

Current = (Charge)/(time)

\(I=\frac{Q}{t}\)

Where\[I\] = The electrical current

\(Q\) = The amount of charge flowing past a point.

\(t\) = The time taken for the charge to flow.

This can give the definition "Current (I) is the (=) amount of charge flowing past a point (Q) per (÷) unit time (t).

Example Calculations

A charge of 15 Coulombs passes through a point in a circuit ever 0.5 seconds. Calculate the current flowing past this point correct to two significant figures. A capacitor stores a charge of 10C. It discharges in 12ms. Calculate the current flowing out of the capacitor correct to two significant figures.
1. State the known quantities

Q = 15C

t = 0.5s

1. State the known quantities

Q = 10C

t = 12ms = 12x10-3s

2. Substitute the numbers into the equation and solve.

\(I=\frac{Q}{t}\)

\(I=\frac{15}{0.5}\)

\(I=30A\)

2. Substitute the numbers into the equation and solve.

\(I=\frac{Q}{t}\)

\(I=\frac{10}{12 \times 10^{-3}}\)

\(I=833.3A\)

\(I\approx830A\)