19,879
edits
Changes
→Example Calculations
===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 0.5 seconds. Calculate the current flowing past this point correct to two [[Significant Figures|significant figures]].
<math>I\approx830A</math>
|}
====Finding Charge from Current and Time====
{| class="wikitable"
| style="height:20px; width: 300px; text-align:center;" |A battery supplies 4Amps 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 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'''
I = 4A
t = 14s
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities'''
I = 7A
t = 5min = 300s
|-
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>I=\frac{Q}{t}</math>
<math>4=\frac{Q}{14}</math>
| style="height:20px; width: 300px; text-align:left;" |'''2. [[Substitute (Maths)|Substitute]] the numbers and [[Evaluate (Maths)|evaluate]].'''
<math>I=\frac{Q}{t}</math>
<math>7=\frac{Q}{300}</math>
|-
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>Q=4 \times 14</math>
<math>Q = 56C</math>
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>Q=7 \times 300</math>
<math>Q = 2100C</math>
|}