physics - electrical currents
- Created by: georgiaweyman
- Created on: 12-10-17 18:43
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- physics - electrical currents
- electrical components
- cell - this is necessary to push electrons around a complete circuit.
- battery- a battery consists of two or more cells
- switch - enables the current in a circuit to be switched on and off
- an indicator (bulb) - emits lights as a signal when a current passes through it.
- a diode - allows current to move in only one direction
- light emitting diode - (LED) gives out light when a current passes through it
- Ammeter - used to measure electric current
- Voltmeter - used to measure potential difference (voltage)
- fixed resistor- limits the current in a circuit by altering resistance
- variable resistor - allows the current to varied/ changed by altering resistance
- thermistor - alters resistance depending on how much it is heated
- light dependant resistor - alters resistance depending on how much light it has
- a fuse - melts to break the circuit if the current is greater than a certain amount
- heater - transfers the energy from an electrical current to the surroundings
- current
- electric current is a flow of electric charge around a circuit
- a bigger current would mean a bigger flow of charge per second
- current is measured in amps
- current is measured using an ammeter
- series circuit - singe loop,same current, voltage splits between components
- parallel circuit - has different paths, current splits between branches, voltage is the same
- charge = current x time (Q=It) (Remember as quit)
- potential difference
- potential difference is the energy transferred to the component in a circuit
- potential difference can also be called voltage
- Energy transferred (J) = charge flow (C) x potential difference (V)
- resistance
- resistance is how difficult it is for the current to flow pass the ions
- more resistance means less current can pass through
- the units for resistance are ohms
- resistance = potential difference * current
- factors that affect resistance
- material = copper has lower resistance than steel so there is a difference in ion size
- length = longer wires have greater resistance as there is more chance of a collision with more ions
- temperature = heating a wire increase its resistance as the ions will have more energy and so moving more, ausing more collisions
- thickness = Smaller diameter wires will have a greater resistance as there is less space
- graphs
- filament lamp (bulb)
- a bulb heats up and temperature increases
- increase in temperature meas increase in resistance and a decrease in current
- fixed resistor
- directly proportional, as current increases potential difference increases
- the steepness shows the resistance
- steeper the line, the lower the resistance
- Ohm's law = Ohmic conductors
- Diode
- only lets current flow in one direction by having a really high resistance in the other direction
- filament lamp (bulb)
- electrical components
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