electromagnetism and solenoids Flashcards
what happens when a current flows through a wire
a magnetic field around the wire will be produced
how do you increase the field strength around a wire
move closer to the wire
or
increase the field strength
what does reversing the current do to the magnetic field
reversing the current reverses the direction of the field
what is the field around a wire like
rings with the wire in the middle
how do you predict the direction of the magnetic field
pretend you are gripping the wire with you right hand and you thumb pointing in the direction of the current flow , the way your fingers curl is the direction of the magnetic field
what is a solenoid
A cylindrical coil of wire
how does the shape of the wire effect the strength of the magnetic field
by bending a current carrying wire into the shape of a solenoid you increase the strength of the magnetic field produced
what does the diagram for the magnetic field of a solenoid look like
similar to a bar magnet with the direction being from North Pole to South Pole
how do you increase the strength of the magnetic field around a solenoid
put an iron core inside the solenoid
what is the magnetic field like inside a solenoid
strong and uniform
how do you work out where the North Pole of a solenoids magnetic field is
If you grip the solenoid so that your fingers curl in the direction of current the North Pole is where your thumb points
what are electromagnets
often solenoids with an iron core
what are the advantages of electromagnets
they can be turned on and off
the strength of the magnet can be increased and decreased by adjusting the current
what are the uses of electromagnets
scrap yard crane- lifting heavy objects with magnetic material in them
electric bell - a switch is used to turn the electromagnet on , the hammer is attracted to the magnet so moves towards it consequently striking the bell. this means the circuit is broken so the electromagnet is turned off
circuit breaker- electromagnet in series with a switch , if the current becomes to strong the switch opens as it becomes attracted to the magnet breaking the circuit
