P4 Electrical circuits Flashcards
What does a cell do?
It pushes electrons around a complete circuit.
How many cells does a battery consist of
2 or more
What does a switch do
Enables the current to be turned on and off
What does a bulb do
It emits light as a signal when a current passes through it
What does a diode do
It only allows the current to flow in one direction
What does an LED do
It emits light when a current passes through it
What does an ammeter do?
It measures an electric current through something
What does a fixed resistor do?
It Limits the current in a circuit
What does a variable resistor do?
It allows the current to be manually adjusted (the amount of resistance)
What does a fuse do?
It melts and breaks the circuit if the current flowing through it is too high
What does a heater do?
It transfers the energy from an electrical current to heat the surroundings
What does a voltmeter do?
It measures the potential difference across (a bulb) (Voltage)
Does a single closed loop circuit have the same current all the way the way through?
Yes
What does it mean if the ammeter is connected in series with the bulb
That its on the same straight line of a circuit
What does it mean if an voltmeter measures the potential difference across a bulb
That the voltmeter is connected in parallel with the bulb
What is the equation to find potential difference
Potential difference (V) = Energy transferred (Joules) Charge (Coulombs)
What is the equation to find resistance
Resistance (Ohms) = Potential difference (Volts)
Current (Ampres)
If there is more resistance is the current bigger or smaller
Smaller
What does ohms law state
That the current through a resistor is directly proportional to the potential difference across the resistor.
Does the resistance of a filament lamp
increase or decrease if the temperature increases
Its resistance increases
Does a thermistors resistance increase or decrease if if its temperature increases
Its resistance decreases
Does an LDR’S resistance increase or decrease if the the light intensity increases
Its resistance decreases
What is potential difference
`the difference in the amount of energy between two points in a circuit
What is the formula for total resistance in a circuit
Total resistance = R1 X R2
If you add more resistors in parallel does the total resistance increase or decrease?
Decrease
What is the equation to find the current through a resistor in a parallel circuit?
Current (amperes) = potential difference (V) Component resistance (Ohms)
