P5-Electric Circuits Flashcards
Describe the forces between objects with
Like charges
Opposite charges
Like charges repel
Opposite charges attract
Explain how static electricity can make clothes crackle when you take them off?
Electrons can get pulled off this leaves a static charge on you and an opposite charge on the jumper
Explain why electric current can flow in metals
Free electrons can move around
Explain what current voltage and resistance are in an electric circuit
Current is the flow of charges around a circuit. It’s measured in amps
Voltage is the driving force that pushes the current around. Units are volts
Resistance is caused by things in the circuit that slow down the flow of change its units ad ohms
What happens to the amount of current in a circuit if the voltage of the battery is increased
The bigger the voltage the bigger the current
What does the power of an appliance measure
Power is the rate at which an electrical power supply transfers energy to an appliance
A remote controlled helicopter has a voltage of 230v and a current of 5 A what is its power rating
230 x 5 =1150
Power = voltage x current
What is another name for voltage?
Potential difference
Calculate the resistance of a wire if the voltage across it is 12v and current through it is 2.5a
Resistance= voltage\current
12\2.5=4.8
Describe how the resistance of an LDR varies with light intensity
In bright light the resistance falls
In darkness the resistance goes up
What happens to the voltage when several batteries are added to a series circus
Bigger total voltage
What voltage is UK mains electricity supplied at?
230
Explain what electromagnetic induction is
You can induce ( create ) a voltage in a conductor by moving a magnet into a coil
Of wire
Explain how a generator works
In a generator a magnet or an electromagnet rotates or an electromagnet rotates inside a coil of wire this induces a voltage across the ends of a coil
What are the four factors that affect the size of the induced voltage produced by a generator
Add an iron core inside the coil
Increase the strength of the magnetic field
Increase the speed of rotation
Increase the number of turns in a coil
What are transformers used for
Transformers are used to change the size of an alternating voltage
A current carrying wire runs parallel to the lines of force of a magnetic field. Does the wire feel a force?
Yeah the wires feel a force
Where does a wire have to be placed to feel the full force of a magnetic field
To feel the full force the wire has to be at right angles to the lines of force of the magnetic field it’s placed in
What part of an electric motor reverses the direction of the current
Commutator
Briefly describe three used of electric motors
DVD players
Electric cars
Domestic appliances
What causes the build up of static electricity?
Caused by rubbing
