Secondary voltage and current?

[SAT2400]

Secondary voltage and current??

Homework Statement

A load resistor is placed across the secondary terminals of a step-down transformer with a turn ratio of 4:1. If the primary voltage and current are 120V and 1A., What will be the secondary voltage and current? Assume 100% efficiency.

Homework Equations

Ns/Np = Vs/Vp = Ip/Is

The Attempt at a Solution

Ns should be 4,,right??
but If Ns = 4..then, I don't get the right answer...
why is Np 4?? Np is primary isn't it??

The answers were 30v and 4A.

 

[tiny-tim]

A load resistor is placed across the secondary terminals of a step-down transformer with a turn ratio of 4:1. If the primary voltage and current are 120V and 1A., What will be the secondary voltage and current? Assume 100% efficiency.
…
Ns should be 4,,right??
but If Ns = 4..then, I don't get the right answer...
why is Np 4?? Np is primary isn't it??

The answers were 30v and 4A.

Hi SAT2400!

It's a step-down transformer, and you're told the ratio is 4:1, so Ns/Np = 1/4.

 

[kerimek]

Yes, you are correct that Ns represents the number of turns on the secondary coil and Np represents the number of turns on the primary coil. In this case, Ns is 4 times Np because the turn ratio is 4:1.

Using the equation Ns/Np = Vs/Vp = Ip/Is, we can solve for Vs and Is. We know that Ns/Np = 4, and we are given Vp and Ip. So, we can plug in these values to the equation to solve for Vs and Is.

Vs/Vp = Ip/Is
Vs/120V = 1A/Is
Vs = 120V * (1A/Is)
Vs = 120V * (1A * 4)
Vs = 120V * 4
Vs = 480V

Is = 1A * (Ns/Np)
Is = 1A * (4/1)
Is = 4A

Therefore, the secondary voltage will be 480V and the secondary current will be 4A, assuming 100% efficiency. It is important to note that in real-life situations, there may be some energy loss and the efficiency may not be 100%, resulting in slightly different values.