• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

dotpoint in motors. (1 Viewer)

1234567

Member
Joined
Oct 13, 2002
Messages
160
explain why voltage transformations are related to conservation of energy.

jacaranda dosn't really say it good
they just say there must be a trade off, but doens't really give reasons or conditions......
 

BlackJack

Vertigo!
Joined
Sep 24, 2002
Messages
1,230
Location
15 m above the pavement
Gender
Male
HSC
2002
Transformers...
Using equation P=VI,the conservation of energy suggests that power in the primary and secondary coil must be equal disregarding wastage, as power is the usage rate of energy over time..

therefore, when voltage changes, up or down between the primary circuit and the secondary, power must be conserved with the change in current. This involves understanding of the conservation of energy..

is this good enough?
 

-=«MÄLÅÇhïtÊ»=-

Gender: MALE!!!
Joined
Jul 25, 2002
Messages
1,678
Location
On Top
Gender
Male
HSC
2002
Power is energy
Conservation law states u cant create or destroy energy, only transform
In 100% efficient transformer power in = power out
No power is lost
P=IV
The transformation occurs in the ratio of I and V
 

1234567

Member
Joined
Oct 13, 2002
Messages
160
so u mean, in a step up transformer, p=iv, since power is equal, and voltage is increased, therefore current in the secondary coil is decreased?

so does that mean when they using the transformer , p stay the same,and the value of current and voltage is constantly being alteerd?
 

BlackJack

Vertigo!
Joined
Sep 24, 2002
Messages
1,230
Location
15 m above the pavement
Gender
Male
HSC
2002
Not constantly altered... They have a fixed ratio, because it is the ratio of the number of coils around the transformer that determines the change of voltage.

The voltage and current stays the same.
(unless you start changing them)...
 

1234567

Member
Joined
Oct 13, 2002
Messages
160
ok......
say from the power station
voltage is steppted up, p=iv, p stays the same, so that means the currnet has to be reduced in this case
then at the household, it's been stepped down, the voltage is reduced, where p still stays the same, dosen't that meanat this point current has been increased?
 

-=«MÄLÅÇhïtÊ»=-

Gender: MALE!!!
Joined
Jul 25, 2002
Messages
1,678
Location
On Top
Gender
Male
HSC
2002
yes increased
but remember current is made up electrons, so the power station is not only sending 1 wire to ur house. The transmission lines split up to every other house. If u split up voltage in a parallet ciruit it remains the same, but if u split a wire into a 2 wires, the current will 1/2.

So wen u say 'increase', the ratio of current to V has increased, but the overall current from the generator has not
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top