What is an ion?
- A charged atom
How does an insulating material become positively charged?
- The material is rubbed against another material, causing loss of electrons.
What does a material do to become negatively charged?
- Gain of electrons
Define electric current.
- The rate of flow of charge in a circuit.
State all of the components you might find in a circuit.
- Battery
- Switch
- Bulb
- Diode
- Light-Emitting Diode (LED)
- Ammeter
- Fixed Resistor
- Variable Resistor
- Fuse
- Voltmeter
Write the equation that links current, charge flow and time taken.
Charge Flow (Q) = Current (I) x Time Taken(t) (couloumbs, C) (amperes, A) (seconds, s)
What is the purpose of a fuse?
- To break the circuit if the current passing through is greater than an amount.
What is the purpose of an LED?
- Emits light when current passes through it.
Give the equation that links potential difference, charge and energy transferred.
Potential difference (V) = Energy Transferred (E) / Charge (Q)
(Volts, V) (Joules, J) (couloumbs, C)State Ohm’s Law
- Current through a resistor at constant temperature is directly proportional to the p.d across the resistor.
Write the equation that links potential difference, resistance and current.
Resistance (R) = Potential Difference (V) / Current (I)
(ohms) (Volts, V) (amperes, A)
Describe a current - potential difference graph of a filament lamp.
- Not directly proportional to the p.d
- Resistance increases as current increases
- Reversing the p.d reverse the current
Describe a current - potential difference graph for a diode.
- In the forward direction, the current isn’t directly proportional to the p.d
- In the reverse, current is zero. The diodes resistance is higher than in the forwards direction.
What happens to the resistance of a thermistor?
- Resistance decreases when temperature increases.
What happens to the resistance of an LDR?
- Resistance decreases as light intensity increases.
For components in series, state the circuit rules.
- Same current passes through each component.
- Total p.d of the power supply is shared between components.
- Total p,d of cells in series = sum of p.d of each cell.
How do you calculate the total resistance of two (or more) components in series?
R = R1 + R2
total
R1 = Resistance of first component R2 = Resistance of second component
For components in parallel, state the circuit rules.
- Total current through the circuit = sum of currents through the separate branches.
- P.D across each component is the same.
- Total resistance of two (or more) components is less than resistance of resistor with the least resistance.
How do you calculate the current through a resistor?
I = V/R
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Chapter 1 - Conservation and Dissipation of Energy9
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Chapter 2 - Energy Transfer by Heating18
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Chapter 3 - Energy Resources11
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Chapter 4 - Electric Circuits19
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Chapter 5 - Electricity in the Home19
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Chapter 6 - Molecules and Matter16
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Chapter 7 - Radioactivity25
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Chapter 8 - Forces in Balance21
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Required Practicals (Paper 1)0
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Required Practicals (Paper 2)0
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Chapter 12 - Waves10
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Chapter 11 - Forces and Pressure2
