4.0 Introduction to circuits Flashcards
Charge def
A property of a body which experiences a force in an electric field
Charge symbol
Q
Charge units
coulombs (C)
Current def
A measure of the flow of electrons around a circuit
In which way does current actually flow
from negative to positive
Current symbol
I (i)
Current units
Amperes or Amps (A)
Potential difference def
The force driving the flow of electrons
(how big the drop is on the waterfall)
Potential difference symbol
V
Potential difference units
Volts (V)
Resistance def
Everything that resists or opposes the flow of electrons
Resistance symbol
R
Resistance units
Ohms (Ω)
What does a wire do
Connects components and passes current easily from one part of a circuit to another
What does a cell do
Pushes electrons around a complete circuit
What does a switch do
Opens and closes to turn a circuit on (closed) or off (open) by not allowing electrons to pass through when open
What does a resistor do
Limits the current in a circuit
What does a variable resistor do
Allows the current to be varied
What does a diode do
Allows current through in one direction only.
What does a fuse do
Designed to melt and therefore ‘break’ the circuit if the current through it is greater than a certain amount
What does a voltmeter do
Measures p.d.
What does an ammeter do
measures current
What does a light-dependent resistor (LDR) do
Changes resistance based on light intensity.
What does a light emitting diode (LED) do
It emits a light when current passes through it
What does a thermistor do
It changes resistance depending on its temperature
What does a heater do
Transfers energy from an electric current to heat surroundings
What does a lamp do
Emits light as a signal when current passes through it
In what way does conventional current flow?
From positive to negative
In what way does conventional current flow?
From positive to negative
