Unit 5: Electrical Systems Flashcards
What is electric charge in a circuit?
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).
Advantage of Circuits in Series:
- It is simpler to construct
Which types of particles carry Electric charge (+/-) ? [PIE]
- Protons
- Ions
- Electrons
(Generally Electrons.)
Difference between Electric charge vs Electric current:
- 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).
Definition of Electric current:
- Flow of electric charge per unit time
SI unit of Electric Current:
An Ampere (I)
Relationship between flow of electric charge per unit time and the electric current.
The greater the flow of electric charge per unit time, the greater the electric current
How do we measure electric current?
We measure how much electric charge is flowing past a point in a circuit per unit time.
How to use an Ammeter?
- 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.
What is the direction of electric current in a closed circuit?
- It flows from the positive terminal to the negative terminal of the power source
What is an Ammeter used for?
To measure the electric current flowing through the circuit
Definition of Potential Difference in a Circuit
The amount of energy needed to move a unit charge between two points in an electric circuit.
What happens when there is a potential difference in a circuit?
Unit charge will flow from a high potential point to a low potential point by itself to ensure a continuous flow in the circuit.
What does the power source do to aid potential difference in the circuit
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)
Why is it important for potential difference to exist in a circuit?
- 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)
Flow from High to Low Potential:
- 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.
Flow from Low to High Potential:
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.
SI unit of Potential Difference
Volt (V)
What is Potential Difference called:
Voltage
What is the instrument used to measure the current flowing through a circuit?
Ammeter
What is the instrument used to measure the potential difference (voltage)
Voltmeter
How to use a Voltmeter?
- 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.
Where is Unit Charge found in?
The electrons, which are already present in the conductive material (wire) of a circuit.
What is Positive Unit charge carried by:
Protons
What is Negative Unit charge carried by:
Electrons
SI unit of Unit charge:
A coulomb (C)
Volt, Joule, Coulomb relations
One Volt may be defined as the one joule of work-done to move a charge of one coulomb.
SI unit of Resistance:
The Ohm (Ω)
Symbol: R
Definition of the electrical resistance of a component
It is the measure of how much the component opposes the flow of electric current.
Electrical conductor with Low electrical resistance
- Copper
- Silver
Electrical conductor with High electrical resistance
- Tungsten
- Nichrome
What is a Resistor in a Circuit?
It is an electrical component that is designed to provide a specific resistance to regulate the amount of current flowing in a circuit.
What are Fixed Resistors used for?
To reduce the amount of current and voltage in electrical components
Which terminal has either high or low potential difference.
Electric charge flowing from the Positive terminal has a High Potential and afterwards it has a Low Potential.
How is the resistance value of Variable Resistors changed?
By adjusting the slider along the metal rod to change the length of wire which current flows.
How does moving the slider of a Variable Resistor reduce the current in a circuit?
When it allows for more length of the conducting wires in which current flows, its resistance increases. Thus the current in the circuit decreases.
How are Resistors important to the functions of a circuit? (3 points)
- 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)
What is the effect of Resistance in a circuit in series:
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
How a Variable resistor works (moving slider)
Increase (Length)
Increased (Resistance)
Decreased (Current) [Ampere]
Decrease (Length)
Decrease (Resistance)
Increase (Current) [Ampere]
What is the effect of Resistance in a circuit in parallel:
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.
Equation to find the Voltage Across a Resistor
V = I x R (Voltage = Current x Resistance)
Relationship between electric current (A) and electric charge (C)
1 Ampere equals to 1 Coulomb of charge passing through a point per second (unit time)
Definition of a heating element:
It is made out of a high-resistance material (such as Nichrome), which can also withstand high temperatures due to its high melting point
Why does a heating element need to have high resistance to electric current?
When electricity flows through, it generates large amount of heat and light energy due to its high resistance
The three types of heating effects of an electric current:
- Household appliances
- Infant incubator
- Autoclaves
The three types of chemical effects of an electric current:
- Electrolysis
- Electroplating
- Extracting pure metals from impurities
Definition of Electrolysis and what is involved in this process:
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.
Ways to strengthen an Electromagnet (4 ways)
- Tighten the coils
- Add more coils
- Increase power supply
- Use an iron core
Definition of Electroplating and what is involved in this process:
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
3 Applications of the magnetic effect of an electric current:
- Robot systems
- Magnetically controlled micobots (surgery)
- MRI scan (produce detailed images of soft tissues)
Definition of Electrolysis (extracting metals from impurities) and what is involved in this process:
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
Definition of the magnetic effect of an electric current:
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
2 harmful effects of electricity:
- 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)
2 safety devices for electricity:
- 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
Definition of Power (W):
The rate of converting electrical energy into other forms of energy
Equation for Power (W)
Power (W) = Energy (J) / Time (s)
SI unit:
Power -> Watt (W)rt5cxD
Energy -> Joule (J)
Formula to find the amount of energy consumed:
Energy consumed (kWh) = Power (kW) x Time (h)
to find joules ->
kWh must be made into W
hours must be made into seconds
Relationship between the resistance and the current:
The smaller the resistance, the greater the current
What does a rheostat do?
It affects the resistanmce
