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Electricity Flashcards

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1
Q

What happens to a Fuse if too large of a current flows through?

A

Fuses melt if too large of a current flows through them.

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2
Q

What do Fuses prevent?

A

Fuses prevent fires as this stops the cable or appliance overheating

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3
Q

What breaks the circuit whenever the current gets too high?

A

Circuit breakers and fuses break the circuit whenever the current gets too high

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4
Q

When do Circuit breakers break the circuit?

A

Circuit breakers break the circuit whenever there’s a surge

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5
Q

What is ‘Earthing”?

A

Earthing is the process that involves offering electrons an alternative pathway to the earth.

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6
Q

What does ‘Earthing’ prevent?

A

Earthing prevents too much electrostatic charge from building up on the surface of an insulator. Less electrostatic charge reduces the risk of electric shock, or the harm it can cause

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7
Q

How does ‘Double Insulation’ help appliances?

A

Double insulation protect appliances by covering appliances in plastic casing and plastic cannot conduct electricity - insulator

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8
Q

What does Resistance cause?

A

Resistance causes transfer of electrical energy to heat energy

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9
Q

What is the formula for power?

A

power = current × voltage

P = IV

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10
Q

What is the formula for energy transferred?

A

Energy transferred = Current x Voltage x Time

E = IVT

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11
Q

What is direct current (d.c.)?

A

A direct current (d.c.) is a current that is steady and has current constantly flowing in the same direction from positive to negative

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12
Q

How many directions could the potential difference across a cell in a d.c. circuit travel in?

A

The potential difference across a cell in a d.c. circuit only travels in ONE DIRECTION

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13
Q

What does a d.c. power supply have?

A

A d.c. power supply has both positive and negative fixed terminals

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14
Q

What produces direct current (d.c.)?

A

Electric cells/batteries produce direct current (d.c)

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15
Q

What is an alternating current (a.c.)?

A

A alternating current (a.c.) is a current that constantly changes its direction, going back and forth around a circuit

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16
Q

What does an alternating current power supply have?

A

A a.c. power supply has two identical terminals that switches between positive and negative

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17
Q

What are 3 advantages of parallel circuits?

A
  1. Components (e.g. bulbs) may be switched on/off independently
  2. If one component breaks, current can still flow through the other parts of the circuit
  3. Bulbs maintain a similar brightness
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18
Q

What are 2 advantages of series circuits?

A
  1. Fewer wires and easier to assemble
  2. Uses less power
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19
Q

What does the amount of current in a series circuit depend on?

A

The amount of current flowing around a series circuit depends on two things:
- The voltage of the power source
- The number(and type) of components in the circuit

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20
Q

What does increasing the voltage of the power source in a series circuit do?

A

Increasing the voltage of the power source drives more current around the circuit

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21
Q

What does decreasing the voltage of the power source in a series circuit do?

A

Decreasing the voltage of the power source reduces the current

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22
Q

What does increasing the number of components do in a series circuit?

A

Increasing the number of components in the circuit increases the total resistance. Therefore, less current flows through the circuit

23
Q

How does changing the resistance in a circuit change the current?

A
  • as you increase the resistance in a circuit, the current will decrease.
  • In an electrical circuit the flow of electrons causes a current.
  • A high resistance makes it harder for the electrons to pass through and therefore, reduces the current
24
Q

What happens to resistance as illumination increases?

A

As illumination increases, resistance decreases

25
Q

Name an electrical component whose resistance decreases as its temperature increases?

A

Thermistor

26
Q

What can a lamp be used for in a circuit?

A

A lamp can be added to a circuit to check for current. If current is flowing the lamp will turn on

27
Q

What is the formula for charge?

A

Charge = current x time

Q = IT

28
Q

What is current?

A

Current is the rate of flow of charge

29
Q

What do Junctions do?

A

Junctions splits current into two or more pathways

30
Q

In a parallel circuit, Is the voltage across two or more components the same?

A

Voltage across components in a parallel circuit is the same

Vt = V1 = V2

31
Q

What is Voltage?

A

Voltage is the energy transferred per unit charge passed

32
Q

What is a volt?

A

Volt is a joule per coulomb

33
Q

What happens to a person if he/she touches an object with a large amount of static charge?

A

If a person touches an object with a large amount of static charge the electrons will flow through the person’s body to the earth - Electric shock

34
Q

Name an electrical component whose resistance decreases when it moved into brighter light.

A

Light dependent resistor (LDR)

35
Q

Describe how an earth wire acts as a safety feature.

A

Provides low resistance path to earth

36
Q

What three components make up an atom?

A
  • Protons
  • Electrons
  • Neutrons
37
Q

Describe an atom’s structure in terms of its components’ position.

A
  • Neutrons and protons in the nucleus
  • Electrons surrounding the nucleus in shells
38
Q

What are the differences between series and parallel circuits regarding current and voltage?

A

SERIES:

  • The same current flows through all the components
  • The potential difference across the components is not the same.
  • The total potential difference is equal to the sum of potential differences across each component

PARALLEL:

  • The current flowing in a junction is equal to the current leaving it.
  • The sum of the currents in each section is equal to the total current.
  • The potential difference across each branch is the same
39
Q

Where must a voltmeter be placed in a circuit?

A

In parallel with the component that is being measured

40
Q

Give an equation relating potential difference with energy transferred and charge.

A

Voltage (V) = energy transferred (J) / Charge (C)

41
Q

What is an ammeter and where must it be connected in a circuit?

A

An ammeter measures current. It is placed in series with the component it is required to measure

42
Q

How can you use a variable resistor to increase the current in a series circuit?

A
  • You set the variable resistor to have a low resistance which should increase the current
43
Q

Explain the relationship between voltage, current, and resistance in a filament lamp.

A
  • As temperature increases in the lamp, the resistance also increases.
  • This is because the higher temperature makes the ions in the filament vibrate more, making it harder for electrons to pass through.
  • This, therefore, decreases the current
  • A filament lamp is not ohmic, meaning the current is not directly proportional to the potential difference.
  • If the voltage is doubled, the current will not be doubled since there will be an increase in resistance
44
Q

When an electrical current flows through a resistor why does it heat up?

A
  • There are collisions between the electrons and the ions in the resistor’s lattice.
  • This causes a transfer of kinetic energy into thermal energy, which is released into the surroundings.
45
Q

How do low-resistance wires reduce unwanted energy transfers?

A

A smaller resistance will mean there are fewer collisions, therefore less energy will be wasted through heating.

46
Q

What is the difference between the function of the live and the neutral main input wires?

A

LIVE:

  • supplies the voltage to the circuit and forms the current within the circuit. Therefore, it is considered the dangerous wire.

Neutral:

  • Used to carry the current away from the appliance.
  • It also completes the circuit so that current can flow.
47
Q

Why is it important to connect a fuse or switch to the live wire?

A
  • When the switch is turned off, or when the fuse melts, it will break the circuit and stop current running through the wire since live wire carries voltage.
  • This provides a method to stop current flowing into the appliance.
48
Q

Which connection is not required when the appliance is double insulated? Give a reason for your answer.

A
  • The earth wire is not required. This is because earth wire is connected to the casing of the material.
  • If the casing is made out of plastic (insulator), the earth wire will not be able to let the current flow to the ground.
49
Q

Give 2 advantages of circuit breakers over fuses

A
  • More sensitive
  • Easier to reset
50
Q

The resistance of the metal filament inside the bulb increases as the potential difference across the bulb increases. Explain why?

A
  • As temperature increases, ions vibrate more/faster
  • Ions gain energy
  • Metal contains free electrons
51
Q

Define voltage

A
  • energy transferred per unit charge passed
52
Q

Describe the effect of increasing the potential difference on the current flowing through the filament wire

A
  • AS the p.d. increases, the current increases as well
53
Q

A feature of electrostatic paint is that the back of the metal frame is painted. Explain why this happens.

A
  • Whole frame is negative
54
Q

A disadvantage of electrostatic paint spraying is that many other things like walls get painted as well. Suggest how this can be avoided.

A
  • Photocopier

Physics (6 decks)

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