# Transformer - Voltage at taps

1. Feb 26, 2012

### fchen720

1. The problem statement, all variables and given/known data

27.An alternating current power supply rated at 120 V is connected to the primary coil of a transformer. The coil has 200 turns. The secondary coil has 600 turns, and is tapped 200 turns from the top end, as shown. What is the reading on voltmeter V1?
(diagram attached)

A.
0 V
B.
40 V
C.
80 V
D.
120 V
E.
360 V

2. Relevant equations

3. The attempt at a solution

I don't know how to solve this but the answer sheet says D.
Would it mean that 120 volts flows east through the middle wire and west through the top?

But then what happens to the 240 volts flowing east through the bottom wire?
If it goes through V1 wouldn't it read 360v?

I would really appreciate it if someone could explain. Thank you.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

#### Attached Files:

• ###### transformer picture.gif
File size:
1.9 KB
Views:
54
2. Feb 26, 2012

### Staff: Mentor

Voltage is a potential --- it doesn't "flow". Think of the the voltmeters as being ideal; they draw no current when they measure the potential across their connections.

If you want to determine the direction of current flow when the taps are connected to some loads, well that is another matter.