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{| class="wikitable"
|[[File:PhetCharges.png|centre|300px|link=https://phet.colorado.edu/sims/html/charges-and-fields/latest/charges-and-fields_en.html]]
|}
==Key Stage 4==
===Meaning===
'''Charge''' is a [[property]] of [[matter]] that can cause an [[Electrostatic Force|electrostatic force]] between two [[object]]s.
===About Charge===
: There are two types of '''charge'''; [[Positive Charge|positive]] and [[Negative Charge|negative]].
: Like '''charges''' [[repel]] each other and opposite '''charges''' [[attract]] each other.
: '''Charges''' create an [[Electrostatic Field|electrostatic field]] which affects other '''charged''' [[object]]s.
: '''Charge''' is a conserved quantity which means; "'''Charge''' cannot be created or destroyed, it can only be transferred from one place to another."
: A flow of '''charge''' is an [[Electrical Current|electrical current]].
===Equation===
====Equation linking Charge, Current and Time====
''NB: You should remember this equation with charge as the subject of the formula.''
'''Charge''' = (Current) x (time)
<math>Q=It</math>
Where:
<math>Q</math> = The amount of [[Electrical Charge|charge]] flowing past a point.
<math>I</math> = The '''electrical current'''
<math>t</math> = The [[time]] taken for the [[Electrical Charge|charge]] to flow.
====Equation linking Charge, Potential Difference and Energy Transferred====
''NB: You should remember this equation with energy transferred as the subject of the formula.''
'''Charge''' = (Energy Transferred)/(Potential Difference)
<math>Q=\frac{E}{V}</math>
Where:
<math>Q</math> = The amount of [[Electrical Charge|charge]].
<math>E</math> = The [[Energy Transfer]]red by the '''charge'''.
<math>V</math> = The [[Potential Difference|potential difference]] between two points.
===Example Calculations===
====Finding Current from Charge and Time====
{| class="wikitable"
| style="height:20px; width:300px; text-align:center;" |A charge of 15 Coulombs passes through a point in a circuit ever 0.52 seconds. Calculate the current flowing past this point correct to two [[Significant Figures|significant figures]].
| 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]].
|-
| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
Q = 15C
t = 0.52s
| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
Q = 10C
t = 12ms = 12x10<sup>-3</sup>s
|-
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>Q=It</math>
<math>15=I \times 0.52</math>
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>Q=It</math>
<math>10=I \times 12 \times 10^{-3}</math>
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>I=\frac{15}{0.52}</math>
<math>I=28.846153A</math>
<math>I\approx29A</math>
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>I=\frac{10}{12 \times 10^{-3}}</math>
<math>I=833.3A</math>
<math>I\approx830A</math>
|}
====Finding Charge from Current and Time====
{| class="wikitable"
| style="height:20px; width: 300px; text-align:center;" |A battery supplies 4.7Amps to a bulb over a period of 14 seconds. Calculate the charge leaving the battery in this time correct to two [[Significant Figures|significant figures]].
| style="height:20px; width: 300px; text-align:center;" |A hairdryer uses a current of 7.2A for 5 minutes to dry a person’s hair. Calculate the charge flowing through the hairdryer in this time correct to two [[Significant Figures|significant figures]].
|-
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
I = 4.7A
t = 14s
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
I = 7.2A
t = 5min = 300s
|-
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>Q=It</math>
<math>Q=4.7 \times 14</math>
<math>Q = 65.8C</math>
<math>Q \approx 66C</math>
| style="height:20px; width:200px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers into the [[equation]] and [[Solve (Maths)|solve]].'''
<math>Q=It</math>
<math>Q=7.2 \times 300</math>
<math>Q = 2160C</math>
<math>Q \approx 2200C</math>
|}
====Finding Time from Current and Charge====
{| class="wikitable"
| style="height:20px; width: 300px; text-align:center;" |A battery charger uses a current of 150mA to deliver a charge of 245 Coloumbs to a battery. Calculate the time taken to charge this battery correct to two [[Significant Figures|significant figures]].
| style="height:20px; width: 300px; text-align:center;" |A cloud in a thunderstorm loses 15kC in one lightening strike. At a current of 31,000kA. Calculate how long this lightning strike lasts correct to two [[Significant Figures|significant figures]].
|-
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
I = 150mA = 150x10<sup>-3</sup>A
Q = 245C
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
I = 31,000kA = 3.1x10<sup>7</sup>A
Q = 15kC = 15x10<sup>3</sup>
|-
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>Q=It</math>
<math>245 = 150 \times 10^{-3} \times t</math>
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>Q=It</math>
<math>15 \times 10^3 = 3.1 \times 10^7 \times t</math>
|-
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>t=\frac{245}{150 \times 10^{-3}}</math>
<math>t=1633.3s</math>
<math>t\approx1633.3s</math>
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>t=\frac{15 \times 10^3}{3.1 \times 10^7}</math>
<math>t = 4.8387 \times 10^{-4}s</math>
<math>t\approx4.8 \times 10^{-4}s</math>
|}