How Does a Model Train Transformer Work?

[jena]

Hi,

My Question:

A model train transformer plugs into 120-V ac and draws 0.35A while supplying 7.5A to the train. (a)What voltage is present across the tracks? (b) is the transformer step-up or step down?

Work

Part A:

I'V'=I"V"
(0.25A)(120V)=(7.5A)(V")
((0.25A)(120V))/(7.5A)=V"
V"=5.6V

Part B:

Step-down, because the secondary voltage is lower than the primary voltage.

Is it correct

Thank You

 

[Doc Al]

You are correct. (Note typo in your part A equations: you wrote "0.25A" instead of "0.35A".)

 

[quicknote]

Hi there,

Your calculations and conclusion are correct. The voltage across the tracks is 5.6V and the transformer is step-down as the secondary voltage is lower than the primary voltage. Great job! Keep up the good work in your studies of electrical circuits and transformers.