Circuits - DC Power pack (6-pin) questions?

[Ascendant78]

Homework Statement

Homework Equations

While equations should be unnecessary to solve these questions, I am not sure if I have done so properly.

The Attempt at a Solution

Well, I placed my answers on the paper already. I am unsure about the potential difference between 12V and 5V, as since neither are grounded, I'm not sure how they have any frame of reference to compare to one another. I'm also not sure about the next 2 questions since only the 5V pin is grounded, but I feel based on my familiarity with circuitry, so long as the 5V and 12V were attached to each other, my answers are correct. Any advice on the right way to look at these (or if I am looking at them wrong and got any wrong answers) would be greatly appreciated.

 

[donpacino]

smart questions...
look at it this way. If there are 12V between +12 and com, and there are 5V between +5 and com, then there will be 7 v (like you said) between +12 and +5. in order for a voltage to be "12V" it has to be "12V" above something else. Voltage is a relative measurement.

all your answers look correct!

 

[Ascendant78]

Well thank you for the feedback. I just wanted to make sure I was looking at it correctly, as the whole concept of a ground being necessary in a circuit as a reference point and some of this not having that reference point threw me a bit off.

 

[NascentOxygen]

How did you determine (d), the potential between -12v and COM?

 

[Ascendant78]

How did you determine (d), the potential between -12v and COM?

I think I messed up and thought the question was asking the same thing as (c), but with the -12V instead of 12V. After you made me take another look at it, I'm now thinking it should be -12V for (d).

 

[NascentOxygen]

How would you explain what circuit arrangement or connections lie behind the pin labelled GROUND?

 

[donpacino]

How did you determine (d), the potential between -12v and COM?

oops, I didn't catch that either :/

 

[NascentOxygen]

I think I messed up and thought the question was asking the same thing as (c), but with the -12V instead of 12V. After you made me take another look at it, I'm now thinking it should be -12V for (d).

Yes, it is -12V.