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5s and 6s Clevedon Science > P6 > Flashcards

Flashcards in P6 Deck (56)
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1
Q

What is this the circuit symbol of, and what does the component do?

A

Variable resistor.

It is used to vary or control the current in a circuit by changing the resistance.

2
Q

What is this the circuit symbol of, and what does the component do?

A

A cell.

It provides a source of energy to the circuit.

3
Q

What is this the circuit symbol of, and what does the component do?

A

A battery.

More than one cell connecetd together or a power supply. It provides energy to the circuit.

4
Q

What is this the circuit symbol of, and what does the component do?

A

A bulb.

If you don’t know what a bulb does, give up now!

5
Q

What is this the circuit symbol of, and what does the component do?

A

A resistor.

Used to alter the amount of current in a circuit.

7
Q

What is this the circuit symbol of, and what does the component do?

A

A light dependent resistor (LDR) . It’s a resistor whose resistance depends on the amount of light falling on it.

8
Q

What is this the circuit symbol of, and what does the component do?

A

A thermistor. A resistor whose resistance depends on its temperature.

9
Q

What is this the circuit symbol of, and what does the component do?

A

An ammeter. Placed in series to measure the amount of current flowing.

10
Q

What is this the circuit symbol of, and what does the component do?

A

A voltmeter. Placed in parallel to measure the voltage across a component.

11
Q

What would changing the variable resistor in this circuit do?

A

It would alter the brightness of the bulb by changing the current in the circuit.

12
Q

If you increase the length of resistance wire in a variable resistor (rheostat) what happens to the resistance and the current?

A

If the wire is longer, there is greater resistance, so the current decreases.

13
Q

For a particular conductor, what happens to the current as the voltage increases?

A

If voltage increases, so does current.

14
Q

What are the units of voltage, current and resistance?

A

Voltage - Volts

Current - Amperes or Amps

Resistance - Ohms

15
Q

How woud you calculate resistance from voltage and current?

A

Resistance = voltage /current

R = V/I

16
Q

Which of these conductors has the highest resistance?

A

C has the highest resitance, as less current flows for a particular voltage.

17
Q

What is this the voltage current graph for?

What happens to the resistance?

A

This is the graph for a filament lamp.

It’s resistance increases the more current flows.

18
Q

Why does the resistance of a filament lamp increase as more current flows through it?

A

For metallic conductors, the collision of charge carriers (electrons) with atoms makes the atoms vibrate more. This increased atomic vibration:
• causes an increase in collisions (increased

resistance)
• increases the temperature of the conductor.

19
Q

What kind of circuit is this?

A

A potential divider circuit.

The potential difference (voltage) is divided or shared out between the 2 resistors.

20
Q

What does the output voltage of a potential divider circuit depend on?

A

The output voltage depends on the
relative values of the resistors R1 and R2.

The voltage is shared in the ratio of the resistors. If R2 is double R1, then it will have twice the voltage across it that R1 has.

e.g. if Vin was 12V, Vout would be 8.

(8 = 4 x 2, and 8 + 4 = 12)

21
Q

What would Vout be when R2 is very much greater than R1? .

A

When R2 is very much greater than R1 the value of Vout is approximately Vin, as almost all the voltage will be used up across R2.

22
Q

What would Vout be when R2 is very much less than R1?

A

When R2 is very much less than R1 the value of Vout is approximately zero, as almost none of the voltage will be used up across R2.

23
Q

Explain how one fixed resistor and one variable
resistor in a potential divider allows variation of the
output voltage.

A

Adjusting the variable resistor changes the anmount of voltage across it. If you increased the resistance of R2 then the output voltage would increase.

24
Q

What happens to the resistance of an LDR when more light falls on it?

A

The resistance decreases when more light falls on the LDR.

25
Q

What happens to the resistance of a thermistor when it gets hotter?

A

The resistance of a thermistor decreases when it gets hotter.

26
Q

What would happen to the output voltage (the reading on the voltmeter) if the thermistor got hotter?

A

If the thermistor got hotter, its resistance would decrease. This means less voltage is dropped across, so the output voltage goes down.

27
Q

How would this circuit change if the resitor was swapped with the LDR?

A

In this diagram, more light means less resistance across the LDR. This means less voltage across it, so more across the resistor. The output voltage increases.

If you were to swap them, then more light would mean less resitance and less voltage across the LDR so the output voltage would decrease.

28
Q

What is a transistor?

A

A transistor is an electronic switch.

29
Q

Draw the circuit symbol for a transistor.

A
30
Q

What are the three terminals of a transistor called?

A
31
Q

What is needed to get a current to flow from the collector to the emitter of a transistor?

A

A small base current (Ib) is needed to switch a greater current flowing through the collector (Ic) and emitter (Ie).

32
Q

How are the currents in a transistor related?

A

Ie = Ib + Ic

33
Q

Describe the benefits and drawbacks of increasing
miniaturisation of electronic components to
manufacturers and to users of the products.

A
34
Q

Complete a labelled circuit diagram to show how an
NPN transistor can be used as a switch for a lightemitting diode (LED).

A
35
Q

Explain why a high resistor is placed in the base
circuit.

A

The base of the transistor would be damaged if too much current flowed. The resistor is there to limit the amount of current.

36
Q

Complete a labelled diagram to show how two transistors are connected to make an AND gate.

A
37
Q

The input signal for a logic gate is either high or low. What does this mean?

A

The input signal for a logic gate is either a high voltage (about 5 V) or a low voltage (about 0 V).

Think of high as ‘1’ or ‘on’ and low as ‘0’ or ‘off’.

38
Q

Which logic gate is this?

A

OR gate

39
Q

Which logic gate is this?

A

AND gate.

40
Q

Which logic gate is this?

A

NOT gate.

41
Q

Which logic gate is this?

A

NAND gate.

42
Q

Which logic gate is this?

A

NOR gate

43
Q

Which logic gate is this the truth table for?

A

OR gate.

44
Q

Which logic gate is this the truth table for?

A

NOR gate

45
Q

Which logic gate is this the truth table for?

A

AND gate

46
Q

Which logic gate is this the truth table for?

A

NAND gate

47
Q

Which logic gate is this the truth table for?

A

NOT gate

48
Q

What is a relay?

A

A relay is switch used to switch between a low voltage logic circuit and a higher voltage mains circuit.

49
Q

Explain why a relay is needed for a logic gate to switch a current in a mains circuit.

A

A logic gate is a low power device that would be damaged if exposed directly to mains power. The relay isolates the low voltage in the sensing circuit from the high voltage mains.

50
Q

What are these the circuit symbols for?

A

A relay.

51
Q

What does this circuit show?

What does the resistor do?

A

It shows how an LED and series resistor can be used to indicate the output of a logic gate. When the output is high the LED (Light emitting diode) comes on.

The resistor limits the current. Too high a current would blow the LED.

52
Q

What do these two circuits show?

A

The circuits show how a thermistor or LDR can be used to control the input to a logic gate.

If the resistance goes down (hotter for thermistor or lighter for the LDR) the voltage across the bottom resistor will increase and if it’s high enough, will send a high input to the logic gate.

53
Q

What does the magnetic field around a current-carrying wire look like.

A

It is circular.

54
Q

What does the magnetic field around a coil carrying a current look like?

A

It’s the same as the field around a bar magnet.

55
Q

What happens if you put a current-carrying wire at right angles to a magnetic field?

A

The magnetic field due to the current in the wire, and the other magnetic field will push against each other. This is the motor effect.

56
Q

How would you use Fleming’s Left Hand Rule to predict the direction of the force on a current-carrying wire?

A

First finger Field

SeCond finger Current

ThuMb Movement

57
Q
A