Zero Point Switching with transformer

[Femme_physics]

So with my final test tomorrow I thought to sneak in another question...

Homework Statement

The following circuit applies switch at the load RL via Zero Point Switching. The ratio of the coil windings at the transformer is N1:N2 = 4:1. The introductory voltage is a sinusoidal type and its RMS value is 100 volts RMS at a frequency of f=40hz. The switch circuit activates switch S the following way:

Every full uneven cycle (from 0 degrees to 360 degrees) the switch is used as a shortcircuit.
Every full even cycle (from 0 degrees to 360 degrees) the switch is used as a disconnection.

http://img42.imageshack.us/img42/2498/zpszps.jpg
1) Based on the data above, draw the voltage on the load at 4 cycles of Vin. In your drawing mark the max voltages positive and negative as well as significant times.

2) Calculate
A) VRL(RMS), IRL (RMS)
B) VRL (AVG), IRL (AVG)
C) PRL (RMS)
D) Vptp

The Attempt at a Solution

http://img849.imageshack.us/img849/7163/wavewavy.jpg

http://img404.imageshack.us/img404/1545/theanswertothequestion.jpg

 

[I like Serena]

Hey Fp.

1) You graph looks good. :S

2a) Your formula for Vrl(rms) does not look right.
There should be a square root in it...

2b) Good.

2c) Same problem
Actually here you should take the average of the powers in each cycle.

2d) Vptp is the peak-to-peak voltage.
What is the highest voltage you have (look at your graph)?
And what is the lowest voltage you have?

 

[Femme_physics]

30 mins before I need to take the test :)

Vptp is 25 volts

2a) Your formula for Vrl(rms) does not look right.
There should be a square root in it...

Are you sure?

Actually here you should take the average of the powers in each cycle.

Hmm...we are told that if we're asked for the power with an AC current, we should always take it as RMS power.

 

[I like Serena]

30 mins before I need to take the test :)

Then I'm probably too late. ;)
Good luck!

Vptp is 25 volts

Better.
But peak-to-peak is -25 to +25, which is 50 V.

Are you sure?

Yes.
It should be 25/√2 volt.

Hmm...we are told that if we're asked for the power with an AC current, we should always take it as RMS power.

Actually, RMS power and average power are the same.