U2 Physics
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- Created by: _bethanyrose_
- Created on: 13-06-17 12:55
Voltage/Current=
Resistance
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What law is used to find the resistance of a component?
Ohm's Law
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What is an Ohmic Conductor?
A component that obeys Ohm's Law and it's current and voltage are proportional.
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What are some examples of Ohmic Conductors?
Copper wires, Filament lamps, a resistor at a constant temperature
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When is Ohm's Law not valid? Why?
When the temperature of the conductor increases because the ions in the components vibrate, making it hard for the electrons to pass through and more collisions take place
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Give an example of where LEDs are used
Bulbs
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Give an example of where LDRs are used
Garden Lights, Burglar Alarms
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Give an example of where thermistors are used
thermostats, fridges, incubators
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Give an example of where diodes are used
converting AC into DC
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What is a series circuit?
A simple circuit with only one loop
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What is a parallel circuit?
A circuit with two or more lopps. It has a junction(s) where the current splits
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Where do currents split?
At junctions
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Is the current the same in all parts of a parallel circuit?
No
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How does the resistance of a series circuit change when you add more resistors?
The resistance increases, therefore the current decreases
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How do you connect an ammeter to a circuit?
Connect it inside the circuit
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How do you connect an voltmeter to a circuit?
Connect it outside the circuit
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What is resistance?
The flow of electric current through most conductors with collisions between ions and electrons
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What is a superconductor?
A substance capable of becoming superconducting at suffiently low temperatures
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Why do some materials have no resistance?
Cool, less vibrations of ions so more electron pathways
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What are the two types of current?
AC (alternating current) & DC (direct current)
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What direction does a direct current go in?
One direction
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What direction does a alternating current go in?
Back and Forth
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What is an oscilloscope?
Shows how the voltage varies with time
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Describe the voltage of an AC current
The voltage of an AC supply follows a repeated pattern: it rises to a peak, returns to zero and changes direction. It crosses the axis
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Describe the voltage of an DC current
The voltage of a DC current supply is steady and always in the same direction. It doesn't cross the axis.
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What type of electricity is provided by a battery?
DC (direct current)
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Describe the electricity that comes out of a wall socket in the UK
AC, 50HZ, 230volts
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What are the three types of wire?
Live, Earth, Neutral
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What does the neutral wire do?
Complete the circuit
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What does the live wire do?
Carries high voltage
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What does the earth wire do?
Creates safety
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What is a fuse?
A safety device the melts when too much current flows through, stopping the electricity flowing.
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What is electrical power?
The rate at which an applicance uses electrical energy.
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What is current measured in?
amps
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What is power measured in?
watts
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Whatis voltage measured in?
volts
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What energy transfer occurs in all electrical appliances?
electrical to heat
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How do you calculate efficiency?
useful output energy/total input energy
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What are the charge carriers in an electrical current?
electrons
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What is charge measured in?
Coulombs
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What do transformers do?
Change the voltage
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What is the National Grid?
A network of cables and transformers
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What do substations do?
House Local transformers
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When an object is charged, what moves the electrons?
Friction
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Other cards in this set
Card 2
Front
What law is used to find the resistance of a component?
Back
Ohm's Law
Card 3
Front
What is an Ohmic Conductor?
Back
Card 4
Front
What are some examples of Ohmic Conductors?
Back
Card 5
Front
When is Ohm's Law not valid? Why?
Back
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