Electricity Flashcards

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0
Q

Why is a PC monitor usually covered in dust?

A

Because the static charges on the monitor attract dust

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1
Q

When plastic is charged by rubbing it with a cloth:

A

It will attract small pieces of paper

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2
Q

Copper does not get charged when rubbed with a cloth because?

A

Copper only conducts electricity

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3
Q

When a piece of plastic has become positively charged it has:

A

Lost electrons

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4
Q

When a piece of plastic becomes negatively charged it has:

A

Gained electrons

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5
Q

When two polythene rods with the same charge are brought near each other they ?

A

Repel because two alike charges repel and two unlike charges attract

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6
Q

If two objects attract to each other,what can’t be true?

A

They won’t have the same charge

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7
Q

When you walk across a nylon carpet, you become negatively charged. When you then touch a metal handle you receive a shock because:

A

Electrons jump from you to the handle

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8
Q

When refuelling an aeroplane, to avoid a spark caused by a build-up of static charge:

A

The refuelling tanker and the aeroplane are both earthed

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9
Q

Atoms that have become charged are:

A

Ions

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10
Q

What component does this circuit symbol represent?

A triangle with a line across the point inside a circle, with two arrows pointing away from it

A

LED

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11
Q

What component does this circuit symbol represent?

A rectangle with an arrow across it

A

resistor

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12
Q

What component does this circuit symbol represent?

A thin, tall line next to a short, fat line

A

cell

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13
Q

When measuring the potential difference across a component, you need:

A

a voltmeter in a parallel circuit

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14
Q

if 3 light bulbs are connected to the same battery, what happens if 1 bulb brakes?

A

nothing will happen and the rest of the bulbs would carry on working

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15
Q

What is the current if 12 C of charge passes in 3 s?

A

4A

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16
Q

What is the potential difference if 24 J of energy is transferred when 6 C of charge passes?

A

4V

17
Q

Why does a copper wire which is 0.5 metre of 0.5 mm diameter wire have the lowest resistance?

A

The resistance in a wire increases as the length of the wire increases and its thickness decreases.

18
Q

If I have two resistors (one 3 ohms and the other 2 ohms),what is the total resistance?

A

5 ohms as 2+3=5

19
Q

Which component does a graph represent when we have a monged up S with current and potential difference down the axis.

A

A filament lamp

20
Q

What happens to a resistor when the temperature is increased?

A

When the temperature of a resistor increases, its resistance increases

21
Q

What happens to a thermistor when the temperature is increased?

A

Its resistance decreases

22
Q

In the circuit the voltage is 6v and the resistance is 12 ohms. What is the current?

A

6 volts ÷ 12 ohms = 0.5 A

23
Q

In the circuit the voltage is 6v and the current is 0.3 amps. What is the resistance?

A

6÷0.3=20 ohms

24
Q

For an LDR, its resistance decreases as :

A

the light intensity increases.

25
Q

12 identical bulbs are connected in series. If their total resistance is 6 Ω,what s the value of each bulb?

A

0.5 Ω

26
Q

The uk mains electricity has ? Hz and how many volts

A

50Hz and 230v

27
Q

What colour is the neutral wire?

A

Blue

28
Q

Why is a hair drier double insulated?

A

It has a plastic outer case

29
Q

Which wore is connected to the fuse?

A

The live wire

30
Q

Batteries produce DC electricity. What does DC stand for?

A

Direct current

31
Q

What is the frequency of a wave with a period of 2?

A

1 divide by 0.2= 5Hz

32
Q

A device transfers 100 J in five seconds, what is its power?

A

100j÷5s = 20w

33
Q

How much energy is transferred by 5w lamp in two minutes?

A

5×120 = 600j

34
Q

A 2A is connected to 1.5 V battery. What is its power?

A

2×1.5=3W

35
Q

A 0.5A lamp is connected to a 12V battery,what is its power?

A

0.55×12 = 6W

36
Q

Television is rated at 460W . What current flows through it at 230V?

A

460÷230 = 2A

37
Q

What happens when an electrical charge flows through a resistor?

A

The temperature increases

38
Q

How much energy is transferred when the potential difference is 6V and the charge is 3C?

A

6×3 = 18J

39
Q

How much energy is transferred when the potential difference is 230 V and the charge is 200 C?

A

230×200 = 46,000J =46 kJ