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→Finding Charge from Current and Time
====Finding Charge from Current and Time====
{| class="wikitable"
| 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 quantities in correct [[unit]]s.'''
I = 4A4.7A
t = 14s
| style="height:20px; width: 300px; text-align:left;" |'''1. State the known quantities in correct [[unit]]s.'''
I = 7A7.2A
t = 5min = 300s
<math>I=\frac{Q}{t}</math>
<math>4.7=\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>7.2=\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 .7 \times 14</math>
<math>Q = 56C65.8C</math>
<math>Q \approx 66C</math>
| style="height:20px; width: 300px; text-align:left;" |'''3. [[Rearrange (Maths)|Rearrange]] the equation and [[Solve (Maths)|solve]].'''
<math>Q=7 .2 \times 300</math>
<math>Q = 2100C2160C</math> <math>Q \approx 2200C</math>
|}