Page 151 - Knowledge Organiser Yr9 24-25

Knowledge Base/Builder: Science P2: Electricity Year 9
6. Knowledge Builder – Resistance required practicals: Resistance Part 2
Describe a method to carry out an investigation into resistors in series circuits.
1. Set up the circuit as shown in the diagram below.
2. Use a voltmeter to measure the potential difference across the
battery and across each resistor.
3. Use the ammeter to record the current in the circuit.
4. Calculate the resistance through each resistor and through the battery.
5. Repeat for different values of resistors to identify a relationship.
6. Repeat this investigation for the second diagram.
A
A
R2 V
R1
6.1
How is a voltmeter connected in a circuit?
In parallel, across the component / components you are measuring.
6.2
When resistors are connected in series, the total resistance is...
The sum of the resistances of the individual resistors.
6.3
When resistors are connected in parallel, the toral resistance is...
Less than the resistance of the lowest resistor.
7. Resistors
7.1
State the relationship between current and potential difference for an ohmic conductor.
Current is directly proportional to potential difference at a constant temperature.
7.2
State an example for an ohmic conductor.
A wire or a fixed resistor.
7.3
Why are resistors and wires ohmic conductors?
Filament lamp and a diode.
7.4
Why are filament lamps and diodes not ohmic conductors?
The resistance stays constant as current changes.
7.5
Why does the resistance of a filament lamp change as the potential difference across it increases?
The resistance changes as current changes.
7.6
State the properties of a diode.
Current increases so temperature increases so resistance increases.
7.7
State the properties of a diode.
Current only flows through a diode in one direction.
7.8
Describe the resistance properties of a thermistor.
As temperature increases, the resistance of the thermistor decreases
7.9
What happens to the resistance of a thermistor as it gets colder?
It increases.
7.10
Describe the resistance properties of an LDR.
As light intensity increases, the resistance of the LDR decreases.
7.11
What happens to the resistance of an LDR as it gets darker.
Increases.
7.12
What happens to the resistance of an LDR as it gets lighter.
Decreases.
7.13
State an example of an application of a thermistor in a circuit.
A thermostat.
7.14
State an example of an application of an LDR in a circuit.
Automatic lighting.
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