chapter three AC generator ( dynamo ) Flashcards
diff the linear velocity and relation and unit
it is the displacement in on second
Vel = DX \ Dt m \ sec
NOTE ; X ⇒ is the displacment or distance coverd
diff angular velocity and relation and unit and all rules you know
it is the angle coverd in one second
ŵ = seta \ t radian \ sec
NOTE ; 2= if seta = 2π = 360 . the time taken be called periodic time ( T )
ŵ = 2π \ T SINCE Freq = 1 \ T
ŵ = 2πF
ŵ = V \ r
NOTE ; r ⇒ length of arc of circle
wedth of the rectangle coil rotates = 2r
what is the function of the dynamo
it is the device to convert the mechanical energy int electric energy
what is the idea of the operation of the dynamo
it depends on the electromagnetic induction when the coil rotates in magnetic filed E.M.F will be indused
what is the construction of the dynamo and the uses
- the filed magnet : it may be a perment magnet or an electric magnet
- the armature : is is a wire loop rotates between the two poles of the magnet
- slip rings with brushes :
- each of the two ends of the coil is connected to one of a pair of slip rings , rotates with the rotation of the loop in the magnetic filed
- each one of the pair of slip rings touches one of two graphite brushes to conduct the induced current from the coil to the external circuit
the dirction of the indused current is reversed each …… turn so it called …………….
- ½
- alternation current
NOte alternating current بيغير اتجاهه دايما
prove the relation on electricromotive force indused in dynamo
draw in page 135
Eind of wire =B x L x V x SINseta
Eind of coil =2 x B x L x V x SINseta
Eind of dynamo =2 x B x L x ŵ x SINseta
since;A = L x 2r (width)
Eind of dynamo = A x B x ŵ x SINseta
for N of number of turns
Eind of dynamo = A x B x N x ŵ x SINseta
diff seta in the relation of the electro motive force in dynamo
it is the angle betweent the dirction of the velocity of the wire and the magnetic flux lines
OR
it is the angle between the normal to the coils plane and the magnetic flux lines
when the indused E.M.F reaches maximum
seta = 90
when the coils plane parallel to the mahnetic flux lines
the indused E.M.F become zero
seta = zero
coils plane perependculer to the magnetic flux lines
what happen during each complete revolution of the dynamo coil on graph and draw it
sin curve in page 136
the indiced E.M.F changes from zero to maximum value to zero to maximum value in opposite direction to zero forming on complete vibration during each complete revolution of the dynamo coil
diff frequency of the AC and the relation and unit
- it is the number of the complete vibrations of the AC in one seconed
OR
it isthe number of the revolutions of the dynamo coil in one second
- F = number of complete revolution \ time
- cycle \ sec OR HZ
what is the number of turns that AC reaches maximum value in one secound
what is the number of turns that AC current reaches zero in on secound
2F
2F+1
- the maximum E.M.F is obtained at angle ……. when the coils plane is to the magnetic flux lines
- Half the maximum E.M.F is obtained at angle ……. when the coils plane makes angle to the magnetic flux lines
- the effective value is obtained at angle ……. when the coils plane makes angle to the magnetic flux lines
- 90
- parallel
- 30
- 60
- 45
- 45
if the E.M.F induced from the dynamo takes time (t) to reach half it maximum value from the starting ZERO position , SO it takes time ……. to reach maximum value while for periodic time or completer revolution ………
- 3t
- 12t