Physics 4.2 - Electricity

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  • Created by: MaxR1
  • Created on: 20-11-18 15:37
Circuit Symbols
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Define Current
Simply defined, electric current is a flow of electrons. Measured in units called “Amperes” (amps for short) and has the symbol A.
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Which equation links charge flow, current and time?
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What does the current through a component depend on?
Potential Difference and Resistance (V = IR or I = V/R). The greater the resistance of the component the smaller the current for a given potential difference (pd) across the component.
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How does Current and Potential Difference behave in an Ohmic Conductor?
(ADD GRAPH) The current through an ohmic conductor (at a constant temperature) is directly proportional to the potential difference across the resistor. This means that the resistance remains constant as the current changes.
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How does Current and Potential Difference behave in a Filament Lamp?
(ADD GRAPH) The resistance of a filament lamp increases as the temperature of the filament increases.
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How does Current and Potential Difference behave in a Diode?
(ADD GRAPH) The current through a diode flows in one direction only. The diode has a very high resistance in the reverse direction.
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How does a thermistor react to increase/decrease in temperature and what applications do they have?
The resistance of a thermistor decreases as the temperature increases. They're often used in thermostats.
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How does an LDR react to increase/decrease in light intensity and what applications do they have?
The resistance of an LDR decreases as light intensity increases. LDRs could be used as a switch so that lights turn on as its surroundings get darker.
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Characteristics or V, I and R in a Series Circuit?
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Characteristics or V, I and R in a Parallel Circuit?
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What is mains electricity and what is the Potential Difference in the UK?
Mains electricity is an ac supply. In the United Kingdom the domestic electricity supply has a frequency of 50 Hz and is about 230 V.
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Which colours indicate the wires of the 3-core mains cable?
live wire – brown neutral wire – blue earth wire – green and yellow stripes.
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What are the roles of the live, neutral and earth wires?
The live wire carries the alternating potential difference from the supply. The neutral wire completes the circuit. The earth wire is a safety wire to stop the appliance becoming live.
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Which equation links Power, P.D. and Current?
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Which equation links Power, Resistance and Current?
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Which equation links Energy Transferred, Power and Time?
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Which equation links Energy Transferred, Charge Flow and P.D.?
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What is the National Grid?
The National Grid is a system of cables and transformers linking power stations to consumers. Electrical power is transferred from power stations to consumers using the National Grid.
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What is the role of transformers in the National Grid?
Step-up transformers are used to increase the potential difference from the power station to the transmission cables then step-down transformers are used to decrease, to a much lower value, the potential difference for domestic use.
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What is Static Electricity?
When certain insulating materials are rubbed against each other they become electrically charged. Negatively charged electrons are rubbed off one material and on to the other. The material that gains electrons becomes negatively charged...
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Explain Electric Fields.
A charged object creates an electric field around itself. The electric field is strongest close to the charged object. The further away from the charged object, the weaker the field. A second charged object placed in the field experiences a force...
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Other cards in this set

Card 2

Front

Define Current

Back

Simply defined, electric current is a flow of electrons. Measured in units called “Amperes” (amps for short) and has the symbol A.

Card 3

Front

Which equation links charge flow, current and time?

Back

Preview of the front of card 3

Card 4

Front

What does the current through a component depend on?

Back

Preview of the front of card 4

Card 5

Front

How does Current and Potential Difference behave in an Ohmic Conductor?

Back

Preview of the front of card 5
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