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Physics > Electricity > Flashcards

Electricity Flashcards

1
Q

What is current?

A

A measure of the flow of electrons around a circuit

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2
Q

What is the unit of Electric Current?

A

Amperes, amps, or ‘A’

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3
Q

What is Potential Difference?

A

The force driving the flow of electrons around a circuit

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4
Q

What is Resistance?

A

Everything that resists or opposes the flow of electrons in a circuit

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5
Q

What Are The Units Of Potential Difference?

A

Voltage, volts, and ‘V’

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6
Q

What is the unit of Resistance?

A

Ohms (Ω)

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7
Q

What is the symbol for a filament lamp?

A

A circle with a cross inside

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8
Q

What is the direction of current flow?

A
  • Electrons flow - Negative → Positive
  • Conventional current - Positive → Negative
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9
Q

What are the circuit symbols for a cell

A

A cell is one long line (positive) and one short line (negative)

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10
Q

What are the circuit symbols for a battery?

A

Two or more cells joined together

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11
Q

What is the definition of charge (Q)?

A

The measure of the total current that flows within a certain period of time

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12
Q

What is the unit for charge?

A

Coulombs (C)

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13
Q

What is the equation for charge (Q)?

A

Q=I×t
Where:
Q = Charge (C)
I = Current (A)
t = Time (s)

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14
Q

What is a series circuit?

A

A circuit with only a single loop, where components are connected one after another

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15
Q

What happens if a component in a series circuit is disconnected?

A

The whole circuit stops working

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16
Q

How is voltage shared in a series circuit?

A

The total voltage of the battery is shared across all components

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17
Q

How is voltage across a single component calculated?

A

V=I×R

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18
Q

What is the function of a voltmeter?

A
  • Measures the potential difference across a component
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19
Q

What happens to components with higher resistance in a series circuit?

A

Components with higher resistance get a larger share of the total voltage

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20
Q

What is a parallel circuit?

A

A circuit with more than one loop, where each loop typically contains only one component

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21
Q

What happens if one component in a parallel circuit breaks?

A

The overall circuit remains intact, and other components continue working

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22
Q

How is voltage shared in a parallel circuit?

A

shared equally across all branches of the circuit

23
Q

How is current shared in a parallel circuit?

A
  • The total current splits between the loops
  • The sum of the currents in all loops equals the total current of the circuit
24
Q

How does resistance affect current in a parallel circuit?

A

Loops with greater resistance take a smaller share of the current, while loops with less resistance take a larger share

25
Q

What happens to the total resistance when more components are added in parallel?

A

The total resistance of the circuit decreases

26
Q

What is the relationship between total resistance and loops in parallel?

A

The more loops added, the lower the total resistance of the circuit

27
Q

Why are parallel circuits more practical than series circuits?

A

In parallel circuits, if one component breaks, the rest of the circuit still works

28
Q

What are the 3 formulas for energy?

A

Energy (E) = Power (P) x Time (t)

Energy (E) = Voltage (V) x Current (I) x Time (t)

Energy (E) = Charge (Q) x Voltage (V)

29
Q

What are the key characteristics of the mains supply in the UK?

A

The mains supply is an alternating current (AC) of 230 volts and 50 hertz

30
Q

What are the three wires in a three-core cable?

A
  • Live wire (Brown)
  • Neutral wire (Blue)
  • Earth wire (Green & Yellow)
31
Q

What is the function of the live wire, and what is its potential difference?

A
  • Provides the alternating potential difference from the mains supply
  • P.D: 230V
32
Q

What is the function of the neutral wire, and what is its potential difference?

A
  • Completes the circuit by carrying away current
  • P.D: 0 Volts
33
Q

What is the function of the earth wire, and what is its potential difference?

A
  • Stops the appliance casing from becoming live
  • P.D: 0 Volts
34
Q

What happens if the live wire touches the casing of an appliance?

A

Provides a safe pathway for current, preventing electric shocks

35
Q

Why is touching the live wire dangerous?

A

Has a potential difference of 230 volts, and since humans have a potential difference of 0 volts, a large current will flow through the body, causing a shock

36
Q

How does electricity flow in a circuit with a three-core cable?

A
  • Flows into the device through the live wire
  • Flows out through the neutral wire
37
Q

Why should you never touch a plug socket, even if it’s switched off?

A

The live wire still has a potential difference, so contact could result in an electric shock

38
Q

What are the wires inside a three-core cable made of, and why?

A

The wires are made of copper because it conducts electricity well

39
Q

Why are wires coated with plastic?

A

The plastic acts as an insulator for safety

40
Q

What are surges in an electrical circuit?

A

Sudden increases in current

41
Q

Why do surges happen?

A
  • Circuit changes
  • Due to faults in the circuit or appliance
42
Q

What can electrical surges cause?

A
  • Damage appliances
  • Cause fires
  • Result in electric shocks
43
Q

What is the function of a fuse in a circuit?

A

Breaks the circuit by melting when the current becomes too high, preventing further current flow

44
Q

How do you select a fuse rating for an appliance?

A

Choose a fuse a few amps higher than the appliance’s normal operating current

45
Q

What are the advantages of fuses?

A
  • Simple
  • Cheap
46
Q

What are the Disadvantages of fuses?

A

Permanently damaged after a surge and need replacing

47
Q

How do circuit breakers differ from fuses?

A

Circuit breakers trip when the current is too high
but can be reset instead of replaced

48
Q

What is the role of the earth wire?

A

Provides an alternative pathway for current to flow away, preventing electric shocks

49
Q

What is double insulation?

A

Double insulation covers appliances with plastic casing

50
Q

Why is double insulation is useful?

A

So there are no exposed metal parts, preventing electric shocks

51
Q

What wires are found in appliances with double insulation?

A
  • Live wires
  • Neutral wires
52
Q

What happens if a live wire touches an appliance’s casing?

A

Make the casing live, and touching it could result in a severe electric shock

53
Q

What are the benefits of circuit breakers over fuses?

A
  • Circuit breakers - can be reset after a surge
  • Fuses - must be replaced
54
Q

How are fuses and circuit breakers similar?

A

Both break the circuit when the current gets too high, preventing damage and electric shocks

Physics (4 decks)

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