Page 150 - Knowledge Organiser Yr9 24-25

Knowledge Base: Science P2: Electricity Year 9
5. Investigating resistance
5.1
What is the independent variable?
The factor you change is the length of the wire
5.2
What is the dependent variable?
The factor you measure is the resistance, by measuring the potential difference and current.
5.3
What are 3 control variables?
The factors that you keep the same are thickness of the wire, density of the wire, potential difference of the battery.
5.4
Name 1 control variable that is difficult to control.
The factor that is difficult to keep the same is the temperature of the wire.
5.5
When current passes through wires and components, what happens to them?
They heat up.
5.6
How does the temperature of a wire affect its resistance?
As temperature increases, resistance increases.
5.7
Why do we switch circuits off between readings?
So the wires don't heat up and cause the resistance to increase.
5.8
How are resistance and current related when potential difference is constant?
Inversely proportional OR as resistance increases, current decreases.
5.9
How are potential difference and current rela ted when resistance is constant?
Directly proportional OR as potential difference increase, current increases.
5.10
How do we check that 2 variables are directly proportional?
Divide the variables at least 3 times. Answer should be the same every time.
5.11
How do we check that 2 variables are inversely proportional?
Multiply the variables at least 3 times. Answer should be the same every time.
5.12
What is a variable resistor?
A component whose resistance can be changed.
5.13
State the relationship between the length of a wire and its resistance.
Directly proportional.
5.14
What does directly proportional look like on a graph?
Straight line through the origin.
Figure 2:
Results graph for required practical: Resistance part 1
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