Changes

: The [[SI Unit|units]] of '''current''' are [[Amp|amperes]], which are also called [[amp]]s ([[A]]).: A '''current''' in a [[wire]] is a flow of [[electron]]s which are [[Negative Charge|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 Charge|positive]] and [[Negative Charge|negative]] [[ion]]s.

'''Electrical current''' is the [[rate]] of flow of [[Electrical Charge|charge]].

: The [[SI Unit]]s of '''current''' are [[Amp|amperes]], which are also called [[amp]]s ([[A]]).: A '''current''' in a [[wire]] is a flow of [[electron]]s which are [[negative]]ly negatively [[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 Charge|positive]] and [[Negative Charge|negative]] [[ion]]s.

''NB: You should remember this equationwith charge as the subject of the formula.''

Where:

Where:

| style="height:20px; width:300px; text-align:center;" |A charge of 15 Coulombs passes through a point in a circuit ever 0.5 52 seconds. Calculate the current flowing past this point correct to two [[Significant Figures|significant figures]].

| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''

t = 0.5s52s| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''

<math>I=\frac{15}{0.552}</math>

<math>I=30A28.846153A</math>

| style="height:20px; width: 300px; text-align:center;" |A battery supplies 4Amps 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 7A 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 quantitiesin correct [[unit]]s.'''

I = 4A4.7A

| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''

I = 7A7.2A

<math>4.7=\frac{Q}{14}</math>

<math>7.2=\frac{Q}{300}</math>

<math>Q=4 .7 \times 14</math>

<math>Q = 56C65.8C</math>

<math>Q=7 .2 \times 300</math> <math>Q = 2160C</math>

<math>Q = 2100C\approx 2200C</math>

| style="height:20px; width: 300px; text-align:center;" |A battery charger uses a current of 150mA to deliver a charge of 240 245 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 15C in one lightening strike. At a current of 3031,000kA. 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 quantitiesin correct [[unit]]s.'''

Q = 240C245C| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''

I = 3031,000kA = 3x103.1x10⁷A

Q = 15kC = 15x10³15C

<math>150 \times 10^{-3} = \frac{240245}{t}</math>

<math>3 .1 \times 10^7 = \frac{15 \times 10^3}{t}</math>

<math>t=\frac{240245}{150 \times 10^{-3}}</math>

<math>t=1600s1633.3s</math>

<math>t=\frac{15 }{3.1 \times 10^37}{3 </math> <math>t = 4.8387 \times 10^{-7}s</math>

<math>t = 5\approx4.0 8 \times 10^{-47}s</math>

| style="height:20px; width:300px; text-align:center;" |A [[Potential Difference|potential difference]] of 9.9V is placed across an 18 19 Ohm [[Electrical Resistor|resistor]]. Calculate the '''current''' flowing through the [[Electrical Resistor|resistor]] correct to two [[Significant Figures|significant figures]].

| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''

R = 18Ω19Ω| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.''' 

<math>I=\frac{9.9}{1819}</math>

<math>I=0.55A52105A</math>