P16: Electricity Flashcards
Ion
A charged atom
Rubbing a polythene rod with a dry cloth…
Transfers electrons to the surface atoms of rod from the cloth, so the rod becomes negatively charged.
Rubbing a perspex rod with a dry cloth…
Transfers electrons from the surface atoms of the rod to the cloth, so the rod becomes positively charged.
Battery.
A cell is necessary to push electrons around a complete circuit. A battery consists of two or more cells.
Switch.
A switch enables the current in a circuit to be switched on or off.
Indicator.
An indicator is designed to emit light as a signal when a current passes through it or as a light source such as a bulb.
Ammeter.
Used to measure current.
Resistor.
Limits the current in a circuit.
Variable Resistor.
allows the current to be varied.
Voltmeter.
Used to measure voltage.
Diode
allows current through in one direction only.
LED
Emits light when a current passes through it.
Fuse
designed to melt and break the circuit if the current through it is greater than a certain amount.
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Heater.
Designed to transfer electrical energy to heat the surroundings.
What way in a circuit does current flow?
+ to -
The size of an electric current…
… is the rate of flow of an electric charge.
What is the unit of electric charge?
Coulombs (C)
Current =
Charge flow (C) / Time taken (s)
Potential difference across the component (V) =
Energy transferred (J) / Charge (C)
What causes resistance?
Electrons having to push past lots of vibrating ions in a metal filament.
resistance (Ω) =
Voltage / Current
Define Ohm’s Law
The current through a resistor at constant temperature is directly proportional to the voltage across the resistor.
2 Non-Ohmic Conductors
Filament Bulb
Diode
1 Ohmic Conductor
Resistor
Thermistor
A resistor that depends on temperature.
Light Dependent Resistor
A resistor that depends on the intensity of light.
In a series circuit, how much current passes through each component?
The same amount.
In a series circit, what happens to the voltage?
It is shared between all of the components.
In a parallel circuit, what happens to the current?
It is split up, and runs through separate components.
In parallel, what is the voltage like for each component?
the same.
