Current and Voltage in a transformer

In summary, the conversation discussed the problem of determining the current and voltage in both the primary and secondary of a perfect transformer with a power of 100W, a flux changing at a rate of 25 Wb/s, and 100 and 500 loops in the primary and secondary respectively. Through the use of the equation V1/V2=N1/N2=I2/I1 and given information about the units of Wb/s, the primary and secondary voltages and currents were calculated to be 2500V and 1/25 A for the primary, and 12500V and 1/125 A for the secondary.
  • #1
btpolk
38
0

Homework Statement



The primary coil in a transformer has a power of 100W. The flux through a single loop in the primary is changing at a rate of 25 Wb/s. The primary has 100 loops and the secondary has 500 loops. Assuming a perfect transformer (no losses), determine the current and voltage in both the primary and secondary.


Homework Equations



V1/V2=N1/N2=I2/I1

?


The Attempt at a Solution



V1/V2=1/5→5V1=V2

I1/I2=5→5I2=I1

I have no knowledge of an equation/relationship between Wb/s and the other variables in this problems nor can I find one. Please Help.
 
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  • #2
A hint can be found in the units: A Weber (Wb) has the equivalent units of V*s (that is, one Weber is a Volt-second).

Given the rate of change 25 Wb/s for a single loop, what's the voltage on the primary?
 
  • #3
So it would be 25W then?
 
  • #4
i mean 2500W since its per loop
 
  • #5
Sorry, I don't understand your response. Your given information states that there is 100W associated with the primary. What's this 2500W you're proposing? Or do you mean 2500V? That would be a reasonable value :smile:

So, if the voltage on the primary is 2500V, what's the current?
 
  • #6
Sorry, I did mean 2500V.

So to find the current I would use

P=V1I1

which would mean that the current would have to equal 1/25 A
 
  • #7
btpolk said:
Sorry, I did mean 2500V.

So to find the current I would use

P=V1I1

which would mean that the current would have to equal 1/25 A

Yes. Now, how will you find the secondary voltage and current?
 
  • #8
5V1=V2

V2=12500V

P=I2V2

I2=1/125 A

Is that right?
 
  • #9
btpolk said:
5V1=V2

V2=12500V

P=I2V2

I2=1/125 A

Is that right?

Your results look good.
 
  • #10
Thanks for the help! I really appreciate it
 

1. What is the difference between current and voltage in a transformer?

Current is the flow of electric charge, while voltage is the force that pushes the electric charge. In a transformer, the current is the amount of electricity passing through the transformer, while the voltage is the amount of force used to transfer the electricity from one coil to another.

2. How are current and voltage related in a transformer?

In a transformer, the current and voltage are inversely related. This means that when the voltage increases, the current decreases, and vice versa. This is known as the transformer's turns ratio, which is determined by the number of turns in the primary and secondary coils.

3. What is the role of current and voltage in a transformer?

The current and voltage in a transformer work together to transfer electric energy from one circuit to another. The transformer changes the voltage level of the electric current, either stepping it up or down, depending on the number of turns in the coils. This allows for efficient transmission of electricity over long distances.

4. How does the current and voltage change in a step-up and step-down transformer?

In a step-up transformer, the voltage is increased while the current decreases, and in a step-down transformer, the voltage decreases while the current increases. This is due to the transformer's turns ratio, which determines the amount of voltage and current in the secondary coil based on the input in the primary coil.

5. What factors affect the current and voltage in a transformer?

The primary factors that affect the current and voltage in a transformer are the number of turns in the primary and secondary coils, the frequency of the input current, and the core material used in the transformer. Additionally, load resistance and transformer efficiency can also impact the current and voltage in a transformer.

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