measuring parallel resistance

I am working through a book which has a multi choice quiz at the end of each chapter . Here is the question

5. The overall resistance of two
parallel resistors is 1 kΩ. The
individual resistance of these
resistors could be:
a 2 kΩ and 2 kΩ
b 3 kΩ and 1k5
c 6 kΩ and 1k2
d 9 kΩ and 1125 Ω
e a and b
f All of these.
g None of these.

by my calculations they all result in 1000 ohms which is f.
but the answer in the back of the book says e.

Am i wrong or the book. If its me thats wrong . Any ideas where i am slippping up.

Thanks Mark S.

"e" is a correct answer but looks like it's isn't the only answer that is correct.

"F" is the answer I would have selected.

Another question in the book which I am not sure is correct.


4. Conventional current flows from
a point of higher electrical potential
to one of lower electrical
potential.
True or false?

I thought the answer would be false because i thought that was describing electron flow. but the book says true.

Whos wrong?

Thanks

Mark S.

Mark S. said:

Another question in the book which I am not sure is correct.


4. Conventional current flows from
a point of higher electrical potential
to one of lower electrical
potential.
True or false?

I thought the answer would be false because i thought that was describing electron flow. but the book says true.

Whos wrong?

Click to expand...

No body really - as the question refers to conventional current flow then a 'higher electrical potential' will be more positive - but it's NOT a very well worded question.

Your book sounds really crap! - and the answer to the first question was 'f'.

The problem with this is you get teachers using the books for setting lessons, and marking them via the provided answers!. We had this at primary school with my daughter, they marked some of her questions as wrong - when we knew they were right - on investigation we found the teacher hadn't even done the questions, just read the answers from the book! (which were wrong). A happy outcome of this was that the teacher then used Melissa's answers as a benchmark - if the book didn't agree with Melissa the teacher would work the question herself, before marking it as wrong (and the book was wrong more often than Melissa!).

Oh no, I smell another, plz hlp me wiv me homwrk, post.

Hero999 said:

Oh no, I smell another, plz hlp me wiv me homwrk, post.

Click to expand...

It's not his fault he has a bad book. At least he did the work himself on the first question and asked for a confirmation...if he made 4 different mistakes 4 times to get the same answer each time...that's pretty far fetched hehe.

COnventional current flow is the opposite of current flow. Electron flow is just that, and conventional current flow refers to the flow of the "holes" left behind as an electron jumps forward. The holes move in the opposite direction as the electrons. THink about it- if you have one electron on the left and a hole (space for an electron) on the right and the electron jumps to the right into the hole, the hole appears to jump to the left in the opposite direction of the electron.

So with + as higher potential and - as lower potential, electrons flow from - to + (lower to higher), but conventional current flows from + to -. Conventional is what is normally used and assumed...usually. It's a legacy wording thing. The question would be false if it said electron flow, but it said conventional current (also known as hole flow).