Electricity and communication Flashcards
(21 cards)
What is one purpose of electric circuits
To transfer energy
Examples of when electric circuits are used
Lights at home, Christmas lights, batteries
What is conventional current
Movement of positive charges, from the positive end of the battery to the negative end
What is electron flow
Flow of electrons, from negative end of battery to positive end.
Describe the term current, in terms of the flow of charge
An electric current is a flow of electric charge. In electric circuits, this charge is often carried by moving electrons in a wire. The higher the pressure, the higher the flow, and vice-versa.
Describe the term voltage, in terms of energy
Voltage is the difference in charge between two points -the amount of potential energy between two points on a circuit. One point has more charge than another. This difference in charge between the two points is called voltage - measured in volts.
What does an ammeter measure
Amps = current, the flow of energy
What does a voltmeter measure
Volts = voltage, amount of energy
Describe a series circuit
Has only one path, current same anywhere in circuit, one bulb fuses = broken
Describe a parallel circuit
Two or more paths, current splits then adds up again, voltage across each pathway = supply voltage, can run with one bulb fused
What do both series and parallel circuits have in common
They convert electrical energy to heat, light, sound, etc.
What is the purpose of a resistor
To slow electrical current
Give an example of when a series circuit is used, and when a parallel circuit is used.
Series - simple circuits e.g. appliances with one switch
Parallel - home electrical circuits, appliances with lots of lights and switches.
Explain the use of resistance in a circuit
Also called ohmic resistance. a property of a conductor by virtue of which the passage of current is opposed, causing electric energy to be transformed into another form of energy. Higher resistance = less current
Ohm’s law: describe the relationship current, voltage and resistance
V
I R
What is the relationship of resistance in a circuit and the heating effect of a current
E.g. bulb is a resistor, material inside slows current and
What is the connection between the resistance of an electric circuit and the heat of a current
Increase in resistance and current = increase in temperature
What is conservation of energy
Efficient energy: most joules will go to good use e.g. not to heat if you want light
Describe conduction
Solids, transfer heat by vibrating around their mean positions, heat transfer in any direction, slow process
Describe convection
Liquids or gases, molecules leave position and carry heat from source upwards, vertically upward direction, faster than conduction
Describe radiation of heat
Type of electromagnetic radiation, no medium needed, can go through vacuum, medium remains unaffected, all directions along a straight path, fast transfer and takes place within the speed of light.
