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Unit 5: Electrical Systems Flashcards

1
Q

What is electric charge in a circuit?

A

Electric charge refers to the quantity of electricity held by an object or particle, which can be positive or negative. It is measured in coulombs (C).

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2
Q

Advantage of Circuits in Series:

A
  • It is simpler to construct
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3
Q

Which types of particles carry Electric charge (+/-) ? [PIE]

A
  • Protons
  • Ions
  • Electrons

(Generally Electrons.)

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4
Q

Difference between Electric charge vs Electric current:

A
  • Electric charge refers to the quantity of electricity held by an object or particle, which can be positive or negative. It is measured in coulombs (C).
  • Electric current (I) is the flow of electric charge through a conductor or circuit. It measures how much charge passes a point per unit of time and is measured in amperes (A).
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5
Q

Definition of Electric current:

A
  • Flow of electric charge per unit time
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5
Q

SI unit of Electric Current:

A

An Ampere (I)

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6
Q

Relationship between flow of electric charge per unit time and the electric current.

A

The greater the flow of electric charge per unit time, the greater the electric current

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7
Q

How do we measure electric current?

A

We measure how much electric charge is flowing past a point in a circuit per unit time.

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8
Q

How to use an Ammeter?

A
  • Must be connected in series
  • Its negative terminal must be connected to the negative terminal of the power source
  • Same goes for its positive terminal.
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9
Q

What is the direction of electric current in a closed circuit?

A
  • It flows from the positive terminal to the negative terminal of the power source
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10
Q

What is an Ammeter used for?

A

To measure the electric current flowing through the circuit

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11
Q

Definition of Potential Difference in a Circuit

A

The amount of energy needed to move a unit charge between two points in an electric circuit.

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12
Q

What happens when there is a potential difference in a circuit?

A

Unit charge will flow from a high potential point to a low potential point by itself to ensure a continuous flow in the circuit.

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13
Q

What does the power source do to aid potential difference in the circuit

A

The power source provides energy to push the charge from a low to a high potential point (in order to create and maintain this potential difference)

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14
Q

Why is it important for potential difference to exist in a circuit?

A
  • Once a unit charge “naturally” flows from a higher to a lower potential point, it will stop moving since it cannot move to the high potential point by itself (requires energy from the power source to “push” it)
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15
Q

Flow from High to Low Potential:

A
  • This flow doesn’t need extra energy because the charge “falls” down the potential difference, similar to how a ball rolls downhill due to gravity.
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16
Q

Flow from Low to High Potential:

A

To move a charge from a low potential point back to a high potential point, energy is required, just like lifting a ball uphill.

This energy is supplied by a power source (like a battery), which “pumps” the charge back to the high potential side, allowing the current to flow continuously.

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17
Q

SI unit of Potential Difference

A

Volt (V)

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18
Q

What is Potential Difference called:

A

Voltage

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19
Q

What is the instrument used to measure the current flowing through a circuit?

A

Ammeter

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19
Q

What is the instrument used to measure the potential difference (voltage)

A

Voltmeter

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20
Q

How to use a Voltmeter?

A
  • Must be connected in parallel
  • Its negative terminal must be connected to the negative terminal of the power source
  • Same goes for its positive terminal.
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21
Q

Where is Unit Charge found in?

A

The electrons, which are already present in the conductive material (wire) of a circuit.

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22
Q

What is Positive Unit charge carried by:

A

Protons

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23
Q

What is Negative Unit charge carried by:

A

Electrons

24
Q

SI unit of Unit charge:

A

A coulomb (C)

25
Q

Volt, Joule, Coulomb relations

A

One Volt may be defined as the one joule of work-done to move a charge of one coulomb.

26
Q

SI unit of Resistance:

A

The Ohm (Ω)

Symbol: R

27
Q

Definition of the electrical resistance of a component

A

It is the measure of how much the component opposes the flow of electric current.

28
Q

Electrical conductor with Low electrical resistance

A
  • Copper
  • Silver
29
Q

Electrical conductor with High electrical resistance

A
  • Tungsten
  • Nichrome
30
Q

What is a Resistor in a Circuit?

A

It is an electrical component that is designed to provide a specific resistance to regulate the amount of current flowing in a circuit.

30
Q

What are Fixed Resistors used for?

A

To reduce the amount of current and voltage in electrical components

31
Q

Which terminal has either high or low potential difference.

A

Electric charge flowing from the Positive terminal has a High Potential and afterwards it has a Low Potential.

32
Q

How is the resistance value of Variable Resistors changed?

A

By adjusting the slider along the metal rod to change the length of wire which current flows.

33
Q

How does moving the slider of a Variable Resistor reduce the current in a circuit?

A

When it allows for more length of the conducting wires in which current flows, its resistance increases. Thus the current in the circuit decreases.

34
Q

How are Resistors important to the functions of a circuit? (3 points)

A
  • To keep the amount of current flowing through a circuit at a safe level to prevent overheating
  • To maintain a fixed amount of current in a circuit
  • Resistors in series divide the total voltage supplied by a power source. (Set-up desirable voltage)
35
Q

What is the effect of Resistance in a circuit in series:

A

It is the sum of all the resistance in each electrical component

R = R1+R2+R3 …

  • The greater the resistance of a circuit, the smaller the current
36
Q

How a Variable resistor works (moving slider)

A

Increase (Length)
Increased (Resistance)
Decreased (Current) [Ampere]

Decrease (Length)
Decrease (Resistance)
Increase (Current) [Ampere]

37
Q

What is the effect of Resistance in a circuit in parallel:

A

The overall resistance of a circuit is less than the resistance of one resistor.

When more components are arrnaged in parallel, the resistances becomes smaller.

  • The smaller the resistance of a circuit, the greater the current.
38
Q

Equation to find the Voltage Across a Resistor

A

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

39
Q

Relationship between electric current (A) and electric charge (C)

A

1 Ampere equals to 1 Coulomb of charge passing through a point per second (unit time)

39
Q

Definition of a heating element:

A

It is made out of a high-resistance material (such as Nichrome), which can also withstand high temperatures due to its high melting point

40
Q

Why does a heating element need to have high resistance to electric current?

A

When electricity flows through, it generates large amount of heat and light energy due to its high resistance

41
Q

The three types of heating effects of an electric current:

A
  • Household appliances
  • Infant incubator
  • Autoclaves
42
Q

The three types of chemical effects of an electric current:

A
  • Electrolysis
  • Electroplating
  • Extracting pure metals from impurities
43
Q

Definition of Electrolysis and what is involved in this process:

A

Electrolysis is a chemical method to break down a compound into its respective elements

  • Electrode: An electrical contact which allows electric current to flow between the electrolyte and the conducting wire, forming a closed circuit.
  • Electrolyte: A liquid or a solution that can conduct electricity.
43
Q

Ways to strengthen an Electromagnet (4 ways)

A
  • Tighten the coils
  • Add more coils
  • Increase power supply
  • Use an iron core
44
Q

Definition of Electroplating and what is involved in this process:

A

Electroplating is the process of coating an object with a layer of metal

Purpose:
- Used as a protective layer of metal (Gold, Silver, Copper)
- To make something more stronger and durable

  • The object to be coated is placed at the negative terminal
  • The metal that coats the other object is placed at the positive terminal
44
Q

3 Applications of the magnetic effect of an electric current:

A
  • Robot systems
  • Magnetically controlled micobots (surgery)
  • MRI scan (produce detailed images of soft tissues)
45
Q

Definition of Electrolysis (extracting metals from impurities) and what is involved in this process:

A

This method helps purify metals by separating pure metal from unwanted impurities using electric current.

  • Impure metal (Anode) - Positive Terminal
  • Pure metal (Cathode) - Negative Terminal
46
Q

Definition of the magnetic effect of an electric current:

A

When an electric current flows through a coil of wire, it generates a magnetic field similar to the one produced by a bar magnet

Known as: The magnetic effect of an electric current

47
Q

2 harmful effects of electricity:

A
  • Electrical fire:
    (when large amounts of electrical current is drawn from the power supply -> caused by overloading of power socket)
  • Electrical shock:
    (Water is a conductor of electricity)
    (When the insulated layers of a wire wears of and we touch the bare wire)
48
Q

2 safety devices for electricity:

A
  • Use of a a fuse in a circuit (has its own fixed rating with a maximum current it allows to flow through, when current is too excessifefef
49
Q

Definition of Power (W):

A

The rate of converting electrical energy into other forms of energy

50
Q

Equation for Power (W)

A

Power (W) = Energy (J) / Time (s)

SI unit:
Power -> Watt (W)rt5cxD
Energy -> Joule (J)

51
Q

Formula to find the amount of energy consumed:

A

Energy consumed (kWh) = Power (kW) x Time (h)

to find joules ->
kWh must be made into W
hours must be made into seconds

52
Q

Relationship between the resistance and the current:

A

The smaller the resistance, the greater the current

53
Q

What does a rheostat do?

A

It affects the resistanmce

54
Q
A

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