P4: Electric circuits Flashcards
what are the charges of each of the sub-atomic particles
proton +
electron -
neutron uncharged
when do some insulators become charged
when you rub them with another insulator such as dry cloth. electrons transfer from one of the materials to another material.
polythene rod with dry cloth
transfers electrons to the surface atoms of the rod from the cloth, polythene rod becomes negatively charged
perspex rod with dry cloth
transfers electrons from the surface atoms of the rod on to the cloth. The perspex rod becomes positively charged, equal to the negative charge of the dry cloth.
what do two charged object exert
a non-contact force on each other. one object creates an electric field and the other experiences a force
what happens to the force between two charged objects as they get closer
it increases
like charges
repel
unlike charges
attract
what does a circuit diagram show
how the components in a circuit are connected together
what do the cell and battery do
push electrons around a complete
what does a fuse do
designed to melt and ‘break’ the circuit if the current through it is greater than a certain.
what is current?
the flow of charge per second
what does a diode do?
only allows the current to flow one way
what kind of circuit is ammeter always measured in
series
where is the voltmeter always placed on the circuit
in parallel to the component we are investigating
what is resistance
a measure of the opposition to the flow of current in an electrical circuit
what is ohms law
the current through a resistor at constant temperature is directly proportional to the potential difference across a resistor.
what does reversing the potential difference across a resistor do?
reverses the current
name one way appliances can fail
too much current passes through a component
what is a thermistor
temperature-dependent resistor. the resistance decreases if the temperature increase
LDR
light dependent resistor, resistance decreases if the light intensity decreases
current in series circuits,
same current passes through each component
potential difference in series
shared between the components
resistance in series
the total resistance of two (or more) components in series is equal to the sum of the resistance of each component
