Electricity Flashcards
What is a Potential Divider?
A part of the circuit that is placed in series with one another.
What are the uses of Potential Dividers?
- Controls temperatures in a freezer
- Uses audio volume controls
- Monitors change in light in a room
What is the equation for Potential Divider?
Vout = (R1/R1+R2) x Vs
What is the Equation for R2?
V1/V2 = R1/R2
Where are magnetic fields found?
Magnetic fields can be found around permanent or electromagnets
What are magnetic fields?
A region around a magnet where a force acts on another magnet or magnetic material.
How can we show magnetic fields lines in real life?
By placing a piece of paper on top of the magnet, and sprinkling iron filings on top. The iron fillings will line up along the magnetic field lines.
What is an induced magnet?
An induced magnetic is a magnetic material that only becomes magnetised once placed in a magnetic field.
What can’t induced magnets do?
They can’t be repelled by other magnets they can only be attracted.
Draw a diagram of the magnetic field around a permanent magnet:
Draw a diagram of two magnets placed close to one another unlike poles opposite:
Draw a diagram of two magnets placed close to one another like poles opposite:
What do the iron fillings become when they are placed on top of the magnet?
They become induced magnets because they have been placed in a magnetic field (of the permenant magnet)
What happens when an induced magnet is taken from the magnetic field?
It loses most or all of its magnetism.
How can we tell that earth has its own magnetic field?
The behaviour of a compass shows us the earth has its own magnetic field. When a compass is placed on its own without a magnet near, it points in the north-south direction. This is the same direction magnetic fields point in. The earth’s magnetic field is due to its core which is made of iron and nickel.
Describe the magnetic field around a current carrying wire:
When electric current moves through a wire, it creates a cylindrical magnetic field around the wire.
What is the direction of the magnetic field around a current carrying wire dependent on?
The direction of the electric current
What is the strength of the magnetic field dependant on?
The bigger current flowing through the wire, the stronger the magnetic field will be.
Where is the magnetic field of a current carrying wire strongest?
The magnetic field is strongest closer to the wire
What is a solenoid?
A solenoid is created when a wire has electrical current moving in it, is coiled up.
(This produces a stronger magnetic field than a straight wire that has electrical current moving through it)
What is the shape of the magnetic field inside the solenoid?
Strong and uniform
What is the shape of the magnetic field around the solenoid?
Similar magnetic field shape of a bar magnet
How the strength of solenoid’s magnetic field be increased?
- If we increase the size of the current, then we increase the strength of the magnetic field
- If we increase the number of turns in the coil
- If we place and iron core, inside of the solenoid (this makes it an electromagnet)
What are some applications of magnets?
Scrap yards, motors and generators, relays, bells, Electric door locks, loudspeakers and headphones, MRI machines, HDD and floppy discs.
Draw a diagram of the magnetic field around a current carrying wire:
Draw a magnetic field of a solenoid and electromagnet:
What is a charge?
A charge is the name you give to one of the properties of an object. An object can either be positively charged (protons) or negatively charged (electrons)
What surrounds all charged objects?
An electrical field. (they are represented as electric field lines)
Draw an electric field around a positive charge, negative charge and between two parallel plates:
What are the charges in a wire
Electrons
What is electric current?
Electric current is the rate of flow of electric charge.
How can we get the electrons in the wire to move in one direction?
Electrons in the wire can move in one direction, if we supply energy to them.
What is the formula for charge?
Q=It
What is the symbol for charge?
Q
What is the unit for charge
Columbs (C)
What is the symbol for current?
I
What is the unit for current?
Amps (A)
What is the symbol for time?
t
What is the unit for time?
seconds (s)
