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Electricity Flashcards

1
Q

Define Electrical Current:

A

-Measure of the amount of charge that
goes past a point in the circuit in one second.
- The flow of charge

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1
Q

Define and Electrical Circuit?

A

A closed loop.
- must have an energy source
- A conducting pathway
-Something to put the energy into.

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2
Q

What is the Symbol, Units and measurement method for Electrical Current?

A

Symbol = I
Measured by an Ammeter
Units = ampere

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3
Q

Name some features of an ammeter:

A
  • Low resistance to allow charge to flow through unmodified.
  • Positive side must be connected to the nearest positive terminal of a battery.
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4
Q

Which way round does the Electrical Current Flow?

A

-Electrons leave the negative terminal of a power supply because they are repelled by the negative terminal
-However, we show the current as flowing from the positive terminal to the negative terminal!

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5
Q

Define Voltage:

A

Voltage is the amount of energy used up by a charge as it moves through a load/resistor.
- called potential difference or
voltage.

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6
Q

What is the Symbol, Units and measurement method for Voltage?

A

Symbol = V
Measured by a Voltmeter
Units = Volts

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7
Q

Name some features of a voltmeter:

A

-Used to measure the voltage/potential difference
between two points in an electric circuit.
-Connected in parallel
-Compare energy electrons have before and after they pass
through a component.
-Voltmeters have a very high resistance (So no charge can pass through them)

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8
Q

Define Resistance:

A

-A measure of how difficult it is
for a charged particle to move through it.

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9
Q

What is the Symbol, Units and measurement method for Resistance?

A

Symbol = R
Measured by Ohms Law
Units = Ohms (Ω)

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10
Q

Compare a Conductor vs and Insulator

A

Conductors allow electricity to flow through whilst Insulators do not allow electricity to flow through easily.

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11
Q

Identify features of a Series circuit:

A
  • 1 continuous circuit
  • If one thing breaks they all break
  • Electrons have to pass through every component to loop back around again.
  • e.g. christmas lights.
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12
Q

Identify features of a parallel circuit:

A
  • more than one path for current to pass through.
  • if one part breaks the current will still continue to flow around component
  • e.g. household lights.
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13
Q

Conditions of drawing a circuit:

A
  • Straight lines/ruler/pencil/eraser
  • Power source goes on top
  • No components on corners
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14
Q

Compare Voltage vs Current in Series and Parallel Circuits.

A

Series Circuits:
- Current is the Same everywhere
- Voltage splits amongst components.
E.g total Voltage = 6 and there are 3 lightbulbs each lightbulb will have 3 volts.
Parallel Circuits
- Current Splits amongst branches
- Voltage is constant everywhere.
E.g. total Current = 12 - 4 currents applied to each branch.

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15
Q

Describe Ohms Laws Triangle:

A

ㅤㅤV
I R

16
Q

What does Ohms Law show:

A

The relationship between voltage drop across an ohmic resistor and the current flowing through it.

17
Q

As the resistance of in a circuit increases the flow of electrons ______ and so does the current.

A

Decreases.

18
Q

As the voltage in a circuit increases, the electrons have more energy and flow faster, and so the current ____

A

Increases.

19
Q

What is an ohmic resistor?

A

An ohmic resistor is a resistor that has a constant resistance.

20
Q

Explain the process of generation of electricity in a coal fired power station:

A
  • Coal is mined and transported to the factories
  • Coal is burned in a furnace
  • Water is turned into steam due to this heat.
  • Steam turns a turbine
  • The steam then travels into cooling towers where it switches back to water to be re used.
  • The turbine that is being spun turn a MAGNET wrapped in a COIL inside a GENERATOR
    -The electrons from the wire begin to move creating a current.
  • The voltage gets stepped up by a transformer.
21
Q

Why does the turbine turn?

A

High pressure steam from the heated water forces this movement.

22
Q

What are step up transformers and step down transformers.

A
  • Step up increase the voltage (good for travelling electricity quickly)
  • Step down decrease the voltage so it is safe to stick into homes. (won’t blow a fuse.)
23
Q

List one disadvantage and one advantage of coal powered plants.

A

Disadvantage: Maximum 50% efficiency.
Advantages: Coal can safely be transported.

24
Q

When a wire is moved in a magnetic field, a voltage is induced causing a _________ to flow.

A

Current.

25
Q

The same thing happens when a magnet rotates inside a ________. This is how ________ is created.

A

Coil.
Electricity.

26
Q

Because the magnet is rotating, the current changes __________. We call this _________ current.

A

Direction.
Alternating.

27
Q

We can increase the current by using __________ coils, a ________
magnet and faster ___________.

A

More.
Stronger.
Motion.

28
Q

What is the equation for calculating the cost of electricity:

A

Total cost = Energy Transferred x Cost per unit.

29
Q

Homer reads his electric meter and he has used 2034 units (kWh) since his last bill. He notices that he gets charged 15.3c per unit. What is his
total bill?

A

Total cost = 2034 x 15.3 = 31120.2c

= $311.20

30
Q

How do you find the kWh (amount of energy used)? (What is the equation)

A

Energy = power x time

31
Q

What does the energy, power, time triangle look like?

A

E
P T

32
Q

Time is measured in?

A

Seconds.

33
Q

Energy is measured in?

A

Joules.

34
Q

Power is measured in?

A

Watts

35
Q

How do you find the power equation?

A

P = e
-
t

36
Q

What is the equation for energy efficiency

A

Energy efficiency = Useful Energy
———————
Total Energy

36
Q

What are some factors that mean not all energy is efficient:

A
  • Heat
  • Light
  • Sound
    Energies

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