P4

What happens when you rub two insulators together?
They may become charged
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How might two insulators become charged?
Electrons will be charged from one material to the other
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What happens when you rub a polythene rod with a dry cloth?
Transfers electrons to the surface atoms of the rod from the cloth- rod becomes negatively charged
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What happens when you rub a perspex rod with a dry cloth?
Transfers electrons from surface atoms of rod to the cloth. Perspex rod becomes positively charged
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Why do two charged exert a non-contact force on each other?
Because of their charge and the electric field they create around themselves
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What is the relationship between two charge objects?
The force becomes stronger as the distance between the objects decrease
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Why do the lines point away from the centre of a charged sphere?
Because the force is directed away from the sphere
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What happens if two objects are positively charged?
Electrons experience a force between the positive object
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What happens if this force is too strong?
Sparking
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Why does it spark?
Because some electrons are pulled out the air molecules by the force of the field, these electrons hit other air molecules and knock electrons out of them causing a sudden flow of them between two charged objects
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What is this?
Diode
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What does a diode do?
Allow current in one direction
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What is this?
A light emitting diode
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What does a light emitting diode?
Lights when current passes through
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What is this?
A fuse
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What does a fuse do?
Designed to melt and break circuit if the current is greater than a certain amount
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What is the size of an electric current?
Rate of flow of charge
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What direction does current flow?
+ to -
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What is resistance in a torch?
The electrons passing through a torch bulb have to push their way through lots of vibrating atoms in the metal filament
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What is current directly proportional to?
Potential difference
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What is Ohms law?
The current through a resistor at a constant temperature is directly proportional to PD across resistor
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Why is a wire called an ohmic conductor?
Because its resistance stays constant as the current changes, provided its temperature is constant
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What happens when you reverse the potential difference across a resistor?
Reverses the current through it
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What is a thermistor?
Is a temperature-dependent resistor
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What happens to the resistance of a thermistor?
Its resistance decreases if its temperature increases
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What happens to the resistance of a light-dependent resistor?
It decreases if the light intensity increases
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What happens to the current in a series circuit?
The same current passes through each component
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In a series circuit what happens to the PD of the power supply?
It is shared between the components
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In a series circuit what happens to resistance?
Total resistance of two in series is equal to the sum of the resistance of each component
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What happens to the current through a parallel circuit?
The sum of the current through the separate branches
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What happens to the potential difference in a parallel circuit?
Each component is the same
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What happens if you add more resistors to a parallel circuit?
It decreases the total resistance
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What happens to the total resistance of two components in a parallel?
Less than the resistance of the resistor with the least resistance
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Other cards in this set

Card 2

Front

How might two insulators become charged?

Back

Electrons will be charged from one material to the other

Card 3

Front

What happens when you rub a polythene rod with a dry cloth?

Back

Preview of the front of card 3

Card 4

Front

What happens when you rub a perspex rod with a dry cloth?

Back

Preview of the front of card 4

Card 5

Front

Why do two charged exert a non-contact force on each other?

Back

Preview of the front of card 5
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