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Physics > Electricity > Flashcards

Electricity Flashcards

1
Q

What is direct potential difference!

A

A supply where the potential difference is fixed at a certain value so current only flows in one direction

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2
Q

What factors affect resistance?

A

. Temperature- the hotter, the more resistance as electrons have more electricity and vibrate and bump into each other blocking path
. Length- longer the more resistance as the electrons have more path to travel more bumping into each other
. Thickness-the thicker, the more resistance

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3
Q

What would a potential difference x current graph for resistance look like?

A

Directly proportional as light goes through (0,0) and as one increases othe increases
Diagonal straight line through graph

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3
Q

How to calculate resistance in series and parallel

A

Series= R1+R2

Parallel= 1/R1+1/R2

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4
Q

What equation links energy transferred and power?

A

Energy= power x time

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5
Q

What is specific heat capacity?

A

The amount of energy required to raise the temperature of 1 kg of substance by 1 degrees

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6
Q

What is the equation for gradient?

A

Y= mx+c

Mx= gradient
C= y intercept

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7
Q

How do you work out efficiency?

A

Efficiency= useful energy output/total energy input

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8
Q

Is efficiency presented in integers, decimals or fractions?

A

Decimals
Always between 0and 1

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9
Q

What is the independent variable?

A

The thing you change

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10
Q

What is the equation for charge?

A

Q=IT

Charge= current x time (s)

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11
Q

Define current

A

The flow of negatively charged electrons

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12
Q

Define charge

A

Measure of how much current is going through something in a certain amount of time

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13
Q

What is the measure of charge?

A

Coulombs (Q)

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14
Q

What is the measure of power?

A

Watts

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15
Q

Will an oscilloscope show results in numbers or diagrams?

A

Line diagrams

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16
Q

Do batteries give direct or indirect current?

A

Direct

17
Q

Define direct current

A

Continuous voltage, current is always going in the same direction

18
Q

Will an alternating voltage, current graph have a straight line, one curve or multiple

A

Multiple going over and under

19
Q

What will a voltage, current graph look like for direct current?

A

A straight horizontal line

20
Q

Are ammeters connected in series or parallel?

A

Series because it doesn’t provide much resistance so won’t affect readings

21
Q

Define resistance

A

How hard it is for electrons to move in an electric circuit

22
Q

Why are metals good conductors of electricity?

A

Have delocalised ions that carry charge

23
Q

How does resistance happen?

A

collisions of the current-carrying charged particles with metal ions that are carrying charge

24
Q

How does increased thickness of wire affect resistance?

A

As you make it thicker, resistance decreases

25
Q

What is Ohms law?

A

Current through a resistor at constant temperature is directly proportional to potential difference across resistor

26
Q

What is static charge?

A

When certain insulators are rubbed together, friction causes electrons to be scrapped off and transferred to the other. The one hat loses electron becomes positively charge vice versa

27
Q

How does static electricity move water?

A

Water is a polar molecule, meaning one end of it is slightly positively charged (the H2 end) and the other is slightly negative (the O end). When the negatively charged insulator is brought towards the stream of water, the positive ends of the molecules are attracted to it and the stream bends towards the charged insulator.

28
Q

What force occurs when two objects are brought close to each other?

A

Electrostatic force

29
Q

When an electric field is strong will the lines be closer or further?

A

closer

30
Q

Why does sparking happen?

A

As an n electric charge builds up, electrons can jump across gap between charged object and earth. A strong field causes electrons in air to be removed. Air become a conductor and charge flows through it

31
Q

What is the equation for energy transferred?

A

energy= voltage x charge

32
Q

What type of current is supplied in UK homes?

A

Alternating current

33
Q

What voltage is supplied in UK homes?

A

230V

34
Q

What frequency is supplied in UK homes?

A

50 Hz

35
Q

What is function of Earth wire? (green and yellow)

A

Safety wire- brings electrons down to earth

36
Q

What is function of fuse?

A

Stops flow of current when it gets too high. Melts or breaks, breaking circuit

37
Q

What is function of neutral wire? What colour is it?

A

completes circuit- carries current away from appliance

blue

38
Q

What is function of live wire? What colour is it?

A

Carries AC potential difference . Not safe to touch.

brown

39
Q

What does the Step Up transformer do?

A

Increase voltage and current decreases

40
Q

What does Step Down transformer do?

A

Reduce voltage and current increases.

41
Q

Is higher or lower current more effective and why?

A

Lower because less energy lost as heat

Physics (3 decks)

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