1. Current is the rate of flow of….. Energy Charge protons
Answer
b) Charge
Bonus
What is the unit of current?
Answer
Amps, A

2. 2) Voltage (potential difference) is the ……..?
Energy transferred per unit charged passed
The rate of charge per second
Current transferred per unit charged passed
a) Energy transferred per unit charged passed
The driving force that pushes the current around
Bonus
What is the unit for Voltage?
Answer
Volts, V (or a Joule / Coulomb, J/C)

3. 3) 1 volt is equal to… 1 joule/charge 1 joule/coulomb 1 Joule/amp
b) 1 joule/coulomb

4. Anything that slows down the flow of current.
4) Resistance is…..;
Rate of flow of charge
Anything that slows down the flow of current.
Answer
b) Anything that slows down the flow of current.
Bonus
What is the unit of resistance?
Answer
Ohms, Ω

5. 5) The bigger the voltage supplied to a circuit… The more the energy
The less the energy
Answer
The more the energy.

6. 6) At junction in a circuit the current is….
Split
Stays the same
Split

7. 7) 6) At junction in a circuit the voltage is….
Split
Stays the same
Ans:
b) Stays the same

8. 8). Ammeter in a circuit measures ….
Voltage
Current
Resistance
Ans:
Current
Bonus: An ammeter is placed in….
Series
In parallel
Bonus: An ammeter is placed in….
Series

9. Bonus: An Voltmeter is placed in…. Series In parallel
9) Voltmeter in a circuit measures ….
Voltage
Current
Resistance .
Ans:.
a) Voltage
Bonus: An Voltmeter is placed in….
Series
In parallel
Bonus: An ammeter is placed in….
Parallel around the component

10. 10) What is a variable resistor used for?
Ans:
Changes the resistance of the circuit which in turn changes the current

11. 11) What are the three voltage-current graphs that must be known (3)
Ans:
Fixed resistor
Filament bulb
Diode

12. 12) Describe using a graph how the current varies with the voltage in a fixed resistor.
Ans:
Current
Voltage
1. Resistor (Constant temp)
Current increases in proportion to voltage

13. 13) Describe using a graph how the current varies with the voltage in a filament bulb?
Ans: .
Current
Voltage
2. Bulb (Filament Lamp)
As voltage increases the bulb gets hotter and resistance increases, current levels off

14. 14) Describe using a graph how the current varies with the voltage in a diode? (2)
Ans:
Current
Voltage
3. Diode
A diode only lets current go in one direction – it has very high resistance in the other direction

15. 15) What is the formula that links current and voltage? (2)
Ans:
V= I X R
Potential difference = Current X Resistance

16. 16) What is a LDR ? (2)
Ans:
It is a light dependent resistor
It’s a resistor that changes its resistance according to the amount of light it receives.

17. In bright light the resistance falls-so curent increases
17) Use a graph to describe how the resistance varies with the light ? (2)
Ans:
In bright light the resistance falls-so curent increases
In darkness , the resistance is the highest
Resistance
Amount of light
1) Light dependant resistor – resistance DECREASES when light intensity INCREASES

18. In hot conditions the resistance falls-so current increases.
18) Use a graph to describe how the resistance varies with the temperature in a thermistor? (2)
Ans:
In hot conditions the resistance falls-so current increases.
In cool conditions , the resistance goes up.
Resistance
Temperature
2) Thermistor – resistance DECREASES when temperature INCREASES

19. 19) Why does an electric component (resistor) become hot when current passes through it ? (2)
Ans:
There is energy transfer so resistor heats up.
Energy transfer is because
electrons collide with ions in the lattice as they move through it.
These collisions give ions extra energy which is emitted as heat.

20. a) Increases the resistors resistance so less current will flow.
20) Heating effect ……
Increases the resistors resistance so less current will flow.
Decrease the resistors resistance so less current will flow.
Decrease the resistors resistance so more current will flow.
Ans:
a) Increases the resistors resistance so less current will flow.

21. 21) Heating effect can cause ……
Can make electrical devices more efficient because less energy is wasted as heat.
Can make electrical devices less efficient because more energy is wasted as heat.
Has no effect on the efficiency of the device.
Ans:
b) Can make electrical devices less efficient because more energy is wasted as heat.

22. 22) Give an example of how the heating effect of an electric current can be useful.
Ans:
Electric toaster or heater.
Toaster or heater contains a coil with very high resistance.
When a current flow through the coil, temperature shoots up, leading to infra-red radiation being given off.
Infra-red radiation cooks the bread in the toaster.

23. 23) What is the equation which links electrical power with current and voltage?.
Ans:
Electrical power = potential difference x current
Bonus
What is the definition of electric power?
Answer
The rate at which energy is transferred in an appliance?

24. 24) High power appliances …
Draw small currents
Large currents
Ans:
b) Large currents
Bonus
What is the unit for power?
Answer
Watts (W)

25. 25) What is the equation that links energy transferred, current, voltage and time
Electrical energy = Current X Potential difference X Time
Electrical energy = IxVxt
Bonus
The energy transferred by a component is dependent on ….
Answer
The current through it, the voltage supplied and how long it is on for measured in seconds.