19,879
edits
Changes
→Example Calculations
| 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 quantitiesin correct [[unit]]s.'''
Q = 15C
t = 0.5s
| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''
Q = 10C
| style="height:20px; width: 300px; text-align:center;" |A hairdryer uses a current of 7A 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 = 4A
t = 14s
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''
I = 7A
| style="height:20px; width: 300px; text-align:center;" |A cloud in a thunderstorm loses 15kC in one lightening strike. At a current of 30,000kA. 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.'''
I = 150mA = 150x10<sup>-3</sup>A
Q = 240C
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''
I = 30,000kA = 3x10<sup>7</sup>A
| style="height:20px; width:300px; text-align:center;" |A toaster has a [[Electrical Resistance|resistance]] of 27 Ohms is plugged into the [[Mains Electricity|mains]] which has a [[Potential Difference|potential difference]] of 230V. Calculate the current flowing through the toaster correct to two [[Significant Figures|significant figures]].
|-
| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''
V = 9.9V
R = 18Ω
| style="height:20px; width:300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''
V = 230V
| style="height:20px; width: 300px; text-align:center;" |Calculating the [[Electrical Resistance|resistance]] of a [[buzzer]] connected in series to a 9V battery with an [[ammeter]] reading of 23mA.
|-
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''
V = 5.4V
I = 0.13mA = 0.13x10<sup>-3</sup>
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantitiesin correct [[unit]]s.'''
V = 9V
<math>R\approx 390\Omega</math>
|}
====Finding Potential Difference from Current and Resistance====
{| class="wikitable"
| style="height:20px; width: 300px; text-align:center;" |A '''current''' of 55mA flows through a [[Electrical Component|component]] with a [[Electrical Resistance|resistance]] of 93 Ohms. Calculate the [[Potential Difference|potential difference]] across this [[Electrical Component|component]] correct to two [[Significant Figures|significant figures]].
| style="height:20px; width: 300px; text-align:center;" |A 22kΩ [[Electrical Resistor|resistor]] has a '''current''' flowing through it of 6mA. Calculate the [[Potential Difference|potential difference]] across the [[Electrical Resistor|resistor]] 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 = 55mA = 55x10<sup>-3</sup>A
R = 93Ω
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
I = 6mA = 6x10<sup>-3</sup>A
R = 22kΩ = 22x10<sup>3</sup>Ω
|-
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>I=\frac{V}{R}</math>
<math>55 \times 10^{-3}=\frac{V}{93}</math>
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>I=\frac{V}{R}</math>
<math>6 \times 10^{-3}=\frac{V}{22 \times 10^3}</math>
|-
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>V= 55 \times 10^{-3} \times 93</math>
<math>V= 5.115V</math>
<math>V\approx5.1V</math>
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>V= 6 \times 10^{-3} \times 22 \times 10^3</math>
<math>V= 132V</math>
<math>V\approx130V</math>
|}