Electricity Flashcards
Why is a PC monitor usually covered in dust?
Because the static charges on the monitor attract dust
When plastic is charged by rubbing it with a cloth:
It will attract small pieces of paper
Copper does not get charged when rubbed with a cloth because?
Copper only conducts electricity
When a piece of plastic has become positively charged it has:
Lost electrons
When a piece of plastic becomes negatively charged it has:
Gained electrons
When two polythene rods with the same charge are brought near each other they ?
Repel because two alike charges repel and two unlike charges attract
If two objects attract to each other,what can’t be true?
They won’t have the same charge
When you walk across a nylon carpet, you become negatively charged. When you then touch a metal handle you receive a shock because:
Electrons jump from you to the handle
When refuelling an aeroplane, to avoid a spark caused by a build-up of static charge:
The refuelling tanker and the aeroplane are both earthed
Atoms that have become charged are:
Ions
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
LED
What component does this circuit symbol represent?
A rectangle with an arrow across it
resistor
What component does this circuit symbol represent?
A thin, tall line next to a short, fat line
cell
When measuring the potential difference across a component, you need:
a voltmeter in a parallel circuit
if 3 light bulbs are connected to the same battery, what happens if 1 bulb brakes?
nothing will happen and the rest of the bulbs would carry on working
What is the current if 12 C of charge passes in 3 s?
4A
What is the potential difference if 24 J of energy is transferred when 6 C of charge passes?
4V
Why does a copper wire which is 0.5 metre of 0.5 mm diameter wire have the lowest resistance?
The resistance in a wire increases as the length of the wire increases and its thickness decreases.
If I have two resistors (one 3 ohms and the other 2 ohms),what is the total resistance?
5 ohms as 2+3=5
Which component does a graph represent when we have a monged up S with current and potential difference down the axis.
A filament lamp
What happens to a resistor when the temperature is increased?
When the temperature of a resistor increases, its resistance increases
What happens to a thermistor when the temperature is increased?
Its resistance decreases
In the circuit the voltage is 6v and the resistance is 12 ohms. What is the current?
6 volts ÷ 12 ohms = 0.5 A
In the circuit the voltage is 6v and the current is 0.3 amps. What is the resistance?
6÷0.3=20 ohms
For an LDR, its resistance decreases as :
the light intensity increases.
12 identical bulbs are connected in series. If their total resistance is 6 Ω,what s the value of each bulb?
0.5 Ω
The uk mains electricity has ? Hz and how many volts
50Hz and 230v
What colour is the neutral wire?
Blue
Why is a hair drier double insulated?
It has a plastic outer case
Which wore is connected to the fuse?
The live wire
Batteries produce DC electricity. What does DC stand for?
Direct current
What is the frequency of a wave with a period of 2?
1 divide by 0.2= 5Hz
A device transfers 100 J in five seconds, what is its power?
100j÷5s = 20w
How much energy is transferred by 5w lamp in two minutes?
5×120 = 600j
A 2A is connected to 1.5 V battery. What is its power?
2×1.5=3W
A 0.5A lamp is connected to a 12V battery,what is its power?
0.55×12 = 6W
Television is rated at 460W . What current flows through it at 230V?
460÷230 = 2A
What happens when an electrical charge flows through a resistor?
The temperature increases
How much energy is transferred when the potential difference is 6V and the charge is 3C?
6×3 = 18J
How much energy is transferred when the potential difference is 230 V and the charge is 200 C?
230×200 = 46,000J =46 kJ
