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Difference between revisions of "Electrical Current"
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: Conventional '''Current''' flows from [[positive]] to [[negative]]. This is because [[electricity]] was discovered before [[scientist]]s knew about [[electron]]s.
 
: Conventional '''Current''' flows from [[positive]] to [[negative]]. This is because [[electricity]] was discovered before [[scientist]]s knew about [[electron]]s.
 
: In a [[salt]] [[solution]] '''current''' is the flow of both [[positive]] and [[negative]] [[ion]]s.
 
: In a [[salt]] [[solution]] '''current''' is the flow of both [[positive]] and [[negative]] [[ion]]s.
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 +
==Key Stage 4==
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===Meaning===
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'''Electrical current''' is the [[rate]] of flow of [[Electrical Charge|charge]].
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===About Electrical Current===
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: '''Current''' is [[measure]]d using an [[Ammeter]].
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: The [[SI Unit]]s of '''current''' are [[Amp|amperes]], which are also called [[amp]]s ([[A]]).
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: A '''current''' in a [[wire]] is a flow of [[electron]]s which are [[negative]]ly [[Electrical Charge|charge]]d [[particle]]s.
 +
: Conventional '''Current''' flows from [[positive]] to [[negative]]. This is because [[electricity]] was discovered before [[scientist]]s knew about [[electron]]s.
 +
: In a [[salt]] [[solution]] '''current''' is the flow of both [[positive]] and [[negative]] [[ion]]s.
 +
: In a [[Series Circuit|series circuit]] the '''current''' is the same everywhere in the [[circuit]].
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: In a [[Parallel Circuit|parallel circuit]] the '''current''' splits at a [[junction]].
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===Equation===
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'''Current''' = (Charge)/(time)
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<math>I=\frac{Q}{t}</math>
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Where:
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<math>I</math> = The '''electrical current'''
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<math>Q</math> = The amount of [[Electrical Charge|charge]] flowing past a point.
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<math>t</math> = The time taken for the [[Electrical Charge|charge]] to flow.
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: This can give the definition "Current (I) is the (=) amount of [[Electrical Charge|charge]] flowing past a point (Q) per (÷) unit time (t).
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===Example Calculations===
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{| class="wikitable"
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| style="height:20px; width:300px; text-align:center;" |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|significant figures]].
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| style="height:20px; width:300px; text-align:center;" |A capacitor stores a charge of 10C. It discharges in 12ms. Calculate the current flowing out of the capacitor correct to two [[Significant Figures|significant figures]].
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|-
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| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities'''
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Q = 15C
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t = 0.5s
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| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities'''
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Q = 10C
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t = 12ms = 12x10<sup>-3</sup>s
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|-
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| style="height:20px; width:300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
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<math>I=\frac{Q}{t}</math>
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<math>I=\frac{15}{0.5}</math>
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<math>I=30A</math>
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| style="height:20px; width:300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
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<math>I=\frac{Q}{t}</math>
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<math>I=\frac{10}{12 \times 10^{-3}}</math>
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<math>I=833.3A</math>
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<math>I\approx830A</math>
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|}

Revision as of 19:26, 24 February 2019

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.

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

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

\(I=833.3A\)

\(I\approx830A\)

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