UNIT THREE Flashcards
what is the motor principle?
when magnets are placed in a perpendicular magnetic field, they will experience a force. magnitudes depend on amount of current in the wire.
what is a galvanometer
device that measures the magnitude of small electric currents.
what is an ammeter?
Used to measure current in amps
what is Lenz Law?
if an induced magnet goes near a current it will oppose the magnetic field. if you pull it away it wants if you push it it doesn’t want
What is domain theory?
who knows but i looked it up and it said large areas in magnets in which the magnetism of the individual atoms and molecules are all aligned in the same direction. so its how magnets be i suppose
what is KCL series?
in a closed circuit, amount of current entering=amount leaving. I1=I2=I3…
What is KCL parallel?
I parallel= I1+I2+I3…
What is kvl series?
v series= v1+v2+v3
what is kvl parallel?
v parallel= v1=v2=v3…
what is resistance series?
R1=R2=R3
WHAT is r parallel
1/RP= 1/R1 + 1/R2 + 1/R3…
how do transformers work?
Honestly? i don’t know. they change the current or voltage to the amount needed. the current induced a magnetic field, magnetic field is changing, induces a current in the secondary coil.
what do the coild have to do with anything
on a transformer, it affects voltage. if winding are low, voltage is also low.
how does N, \v, and I change between coils in step up transformer?
primary secondary Np < NS VP < Vs IP > Is THIS IS OPPOSITE IN STEP DOWN.
how does a DC motor work?
the current flows in one direction, carbon brushes allow the current to flow through the loop. wen the loop is vertical (at max magnetic force) the carbon brushes are on insulators and brush keeps spinning due to inertia, before current changes so the magnet is reversed.
what effects the strength of an electromagnet?
the current, (greater current = greater magnetic field)
the number of loops, (magnetic field = sum of all its loops. # loops = # electric)
type of core, (adding an iron core will strengthen the magnet as it will become an induced magnet)
what is an electromagnet?
a device that exerts a magnetic force with electricity. its kinda telling
what happens when current is bent into a coil?
it makes a magnetic field of a bar magnet
what is true about straight conductors?
the magnetic fields are circular and do not touch, there are no poles, and field lines go opposite when the current is reversed.
what is the third Right Hand Rule?
point fingers in direction of current (North to South) point your thumb in the direction of the current. pretend your palm is pushing it away.
what is the second Right Hand Rule?
curl the fingers in the direction of the current, thumb points to the north pole.
What is the first Right Hand Rule?
if the straight conductor is held in the right hand, the thumb points in the direction of the current and,the fingers curl in the direction of magnetic field lines
how to calculate cost?
P=V^2/R or equivalent
make sure P is in kW
E= pt
Cost = consumption x price
how to calculate mv to v?
divide mv by 1000
1/rp?
1/rp = 1/r2 + 1/r3 (or whatever the line is in between)
