Electricity Flashcards
Define Electrical Current:
-Measure of the amount of charge that
goes past a point in the circuit in one second.
- The flow of charge
Define and Electrical Circuit?
A closed loop.
- must have an energy source
- A conducting pathway
-Something to put the energy into.
What is the Symbol, Units and measurement method for Electrical Current?
Symbol = I
Measured by an Ammeter
Units = ampere
Name some features of an ammeter:
- Low resistance to allow charge to flow through unmodified.
- Positive side must be connected to the nearest positive terminal of a battery.
Which way round does the Electrical Current Flow?
-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!
Define Voltage:
Voltage is the amount of energy used up by a charge as it moves through a load/resistor.
- called potential difference or
voltage.
What is the Symbol, Units and measurement method for Voltage?
Symbol = V
Measured by a Voltmeter
Units = Volts
Name some features of a voltmeter:
-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)
Define Resistance:
-A measure of how difficult it is
for a charged particle to move through it.
What is the Symbol, Units and measurement method for Resistance?
Symbol = R
Measured by Ohms Law
Units = Ohms (Ω)
Compare a Conductor vs and Insulator
Conductors allow electricity to flow through whilst Insulators do not allow electricity to flow through easily.
Identify features of a Series circuit:
- 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.
Identify features of a parallel circuit:
- 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.
Conditions of drawing a circuit:
- Straight lines/ruler/pencil/eraser
- Power source goes on top
- No components on corners
Compare Voltage vs Current in Series and Parallel Circuits.
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.
Describe Ohms Laws Triangle:
ㅤㅤV
I R
What does Ohms Law show:
The relationship between voltage drop across an ohmic resistor and the current flowing through it.
As the resistance of in a circuit increases the flow of electrons ______ and so does the current.
Decreases.
As the voltage in a circuit increases, the electrons have more energy and flow faster, and so the current ____
Increases.
What is an ohmic resistor?
An ohmic resistor is a resistor that has a constant resistance.
Explain the process of generation of electricity in a coal fired power station:
- 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.
Why does the turbine turn?
High pressure steam from the heated water forces this movement.
What are step up transformers and step down transformers.
- 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.)
List one disadvantage and one advantage of coal powered plants.
Disadvantage: Maximum 50% efficiency.
Advantages: Coal can safely be transported.
