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Physics > Electrical Quantities > Flashcards

Electrical Quantities Flashcards

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1
Q

What is static electricity?

A

Static electricity is all about charges which are not free to move. As a result they build up in one place, resulting in a spark or shock when they do move.

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2
Q

How are materials charged?

A

Insulating materials , such as polythene and perspex , can be charged by rubbing them with a dry woolen cloth.

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3
Q

How do like and unlike charges react together?

A

Like charges will try to repel each other (++) (- -)
Unlike charges will try to attract each other. (+ -)

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4
Q

How does distance affect the force between like charges?

A

The closer the charges, the greater the force between them.

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5
Q

When two insulators rub together which charges move to the other material?

A

Only electrons move, never the positive charges!
One of the materials will then be positively charged and the other will be negatively charged

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6
Q

What are conductors?

A

Conductors allow electrons to pass through them. Metals have ‘free’ electrons between the individual atoms, and this makes them excellent conductors. The free electrons also make them good conductors of thermal energy (heat).

Eg: Metals (copper , gold) and carbon

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7
Q

What are insulators?

A

electrons are held tightly to their atoms so are not free to move, and so do not conduct electricity (but electrons can be transferred by rubbing – static charging).

Eg: Plastics, Glass, Dry air

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8
Q

What are semi-conductors?

A

neither an insulator or a conductor. Poor conductors when cold, but much better conductors when warm.

Eg: Silicon and Germanium (metalloids)

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9
Q

What is electricity?

A

is the flow of electrons around a circuit.

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10
Q

What flows from the positive to negative in a circuit?

A

Conventional current direction

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11
Q

What flows from the negative to the positive in a circuit ?

A

Electron direction

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12
Q

Why are circuits made up of metal?

A

Electric current will only flow if there are charges which can move freely. And metals are conductors which have a sea of delocalized electrons.

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13
Q

What is voltage?

A

is the amount of energy given to electrons as they travel around the circuit.

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14
Q

What is another name for voltage?

A

Potential Difference (PD)

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15
Q

What is current?

A

is the rate of flow of electrons around a circuit.

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16
Q

How does current affect the rate of electrons traveling?

A

The higher the current, the faster the electrons are travelling

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17
Q

What’s the unit of voltage/PD?

A

Unit of voltage or PD is the volt.

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18
Q

What is the relationship between volts and joules?

A

1 volt = 1 joule of potential energy is given to each coulomb of charge
(1J = 1 J/C)

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19
Q

What is the unit of current?

A

The unit of current is the amp (ampere singular)

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20
Q

What is the battery cell function?

A

The battery cell gives electrons potential energy. This energy is then passed on to the components in the cell

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21
Q

What is the EMF?

A

The maximum Potential Difference (PD) of a battery is known as the electromotive force (EMF) of the cell.

22
Q

When does a battery cell produce its highest potential difference (PD) / Electro motive force (EMF), Why?

A

The cell produces its highest potential difference when not connected in a circuit.
As soon as the cell is connected in a circuit the potential difference drops because of energy wastage inside the cell.

23
Q

What is a battery cell?

A

A battery is a series of joined cells, although it is commonly used for a single cell as well. The longer line is the positive charge , the shorter line the negative charge.

24
Q

What equipment do we use to measure voltage?

A

Voltmeter,
It looks like a V inside a circle

25
Q

Where do we place the voltmeter in a circuit?

A

To measure the voltage across a component in a circuit the voltmeter must be placed in parallel with it.

26
Q

What equipment do we use to measure current?

A

Ammeter
It looks like an A inside a circle

27
Q

Where do we place an ammeter in a series circuit?

A

Ammeters can be placed anywhere in a series circuit and will all give the same reading.
-l
On the l

28
Q

How does resistance affect current in a parallel circuit?

A

In a parallel circuit the current through each component depends upon its resistance. The higher the resistance the lower the current.

29
Q

Where should you position an ammeter in a parallel circuit?

A

You should place an ammeter next to each light bulb. And you should place one in the series to compare the total current to the divided current.

1l_l
2l_l
3l_l

Place one in number 1 _
Place one in number 2 _
Place one in number 3 _
Place one in number 1 or 2 or 3 l

30
Q

What happens to current and voltage in a series circuit?

A

Current is the same, voltage is divided.

31
Q

What happens to current and voltage in a parallel circuit?

A

Current is divided
Voltage is the same

32
Q

How to find the total current in a parallel circuit?

A

The total current flowing around the circuit is equal to the total of all the currents in the separate branches.

33
Q

How to find the total voltage in a series circuit.?

A

Th total voltage is equal to all the voltage of the different light bulbs added together

34
Q

What is the formula for voltage?

A

Voltage (V) = Current (I) x Resistance (R)

35
Q

What is the formula of current (I)?

A

Voltage (V)
Current (I)= ——————
Resistance (R)

36
Q

What is the formula of resistance (R)?

A

Voltage (V)
Resistance (R) = ————————-
Current (I)

37
Q

What is the unit of voltage ?

A

Volts (v)

38
Q

What is the unit of current?

A

Amps (A)

39
Q

What is the unit of Resistance?

A

Ohms (Ω)

40
Q

If the line in a graph of current and voltage is steady and straight what do we say?

A

It obeys the ohms law

41
Q

What is the device used to measure resistance ?

A

Resistor

42
Q

In a graph of current and volts where are they positioned?

A

Volts go on the y-axis
Current goes on the x-axis

43
Q

What happens if you increase the temperature of a resistor?

A

The resistor in a metal has positive ions and a sea of delocalized electrons . Those electrons flow around the circuit carrying the current. If you increase the temperature you increase the kinetic energy of the positive metal ions. So the positive metal ions vibrate more. If they vibrate more they prevent the electrons from flowing around the circuit so easily , therefore increasing the resistance. So that means if you increase the temperature of a resistor, the resistance increases .,

44
Q

What is a variable resistor?

A

Is a resistor of which the electric resistance value can be adjusted

45
Q

What is a heater?

A

is an electrical device that converts an electric current into heat

46
Q

What is an LED filament lamp?

A

Is a lamp that saves energy

47
Q

What is a battery?

A

It has more than one cells

48
Q

What is a resistor ?

A

is an electrical component that limits or regulates the flow of electrical current in an electronic circuit.

49
Q

What is another name of static electricity?

A

Electrostatic charge

50
Q

What is the unit of charge?

A

The unit of charge is the coulomb (C)

Physics (8 decks)

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