Electromagnetism Flashcards
How can we prove that there is a magnetic field around a current carrying conductor
By placing compasses around the conductor or by sprinkling iron fillings around the current carrying conductor
Magnetic field lines lie in concentric circles around the conductor and in a plane perpendicular to the conductor the two methods above exhibit that
What is the right hand rule
Grasp the conductor I’m your right hand so that your thumb points in the direction of the conventional current. The direction that your bent fingers are pointing is the direction of the magnetic field
What is the right hand solenoid rule
Hold the solenoid in your right hand, with your bent fingers pointing in the direction of conventional current, the extended thumb points in the direction of the N pile of the solenoid
What are some important uses of electromagnets
Electronic bells, speakers, lifting of motor car wrecks and pieces of iron in a scrap yard
What determines the strength of a solenoid
1) the number of turn in the solenoid
2) the current through the solenoid
3) the type of substance from which the core metal placed in the coil is made of
What is the environmental impact of electrical overhead cables
-The magnetic field around the cables might be harmful to people and animals
- the land cleared to make space for cable pylons destroys natural habitat for plants and animals
Define electromagnetic induction
The phenomenon where an emf, as well as an electrical current is induced in a conductor by an altered magnetic field around the conductor
Explain electromagnetic induction
Relative movement between the magnet and the solenoid causes an alternating magnetic field and thus causing and induced emf. The emf in the solenoid causes an induced current
What determines the strength of the emf across the solenoid
-strength of the magnet
- amount of turns on the solenoid
- speed at which the magnet or solenoid moves
What is a Tesla
The magnetic flux per square meter of the surface it moves through
What is magnetic flux
The product of the perpendicular component of the magnetic field through a surface, and the size of the surface.
What is faradays Law
the emf induced is directly proportional to the rate of change of magnetic flux
What is lenz’s law
the induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux
What is the formula for magnetic flux
Ф = BA cos θ where B is the magnetic field strength, A is the area of the area of the loop and θ is the angle between the magnetic field lines and the normal of the surface of the loop
