Circuits Flashcards
(26 cards)
What is current
A rate of flow of electrical charge
How many seconds does it take for a electrical charge to flow
Per second
What is current measured in
Amps (A)
What charges flow in a circuit
Electrons
What is charged measured in
Coulombs (C)
What is Potential differences (p.d)
It is the energy transferred per unit charge
What is p.d measured in
Volts
What is resistance
An material’s opposition to electric current
What is resistance measured in
Ohms
What is the equation
Resistance (ohms) = p.d (V) / current (A)
R=V/I
What does the cell provide in the circuit
P.d
In a circuit what does the battery have
Two or more cells connected together
What does a Fixed resistor do in a circuit
Used to restrict the amount of current in the circuit. The greater the resistance the smaller the current
What does a variable resister do
It can have different values of resistance
Vary the amount of currents in the circuit
What is an ammeter
record amount of current in the circuit.
connected in series with components
What is a voltmeter
records the p.d across a component.
must be placed in parallel with the component
Fixed resister
It’s a resister or a wire at constant temperature
Obeys the Ohms Law - this means that current is directly proportional to p.d
(Resistance stays constant it temperature is constant)
Filament Lamp
It will not obeys Ohms Law
As the p.d is increased the temperature will increase - this means that ions in the metal filament vibrate more and restrict the flow of electrons - will increase the resistance
Diode
In the forward direction current can flow but in the reverse the component has a very high resistance and only a tiny current can flow - this means that a diode will only allow current to travel one way round the circuit.
LED - lights emitting Diode
Emits light when a current passes through it in a forward direction.
Used in indicators as electrical device
LDR - light dependent Resister
Sensitive to light levels
In light the resistance is low in the dark it is high
Used as a sensor to control other devices
Thermistor
Sensitive to temperature
Resistance is low at high temperature - high in low temp
Used to switch the heating on and off
In a series circuit is current the same through each component
Yes
What cell is shared between the components
Pd
