# Electricity: Basic circuit question with a switch

Gold Member
Not the signs - the symbols!

I'll leave the final question for tomorrow. The 2nd term, by the way, is the day after tomorrow^^ So tomorrow is super electronics practice day! I hope to have you with me

Gold Member
And here is the final question that made me skip the question

Q: In which of the two cases (open switch or closed switch) will the wasted power of the circuit bigger. By how much?

What do they mean? Didn't we do that in the earlier clause? Comparing powers? What exactly is "wasted power"? If I'm translating it correctךט

ההספק המבוזבז

I like Serena
Homework Helper
Good morning Fp!

There! We're back to deducing what was intended by a word.

Why didn't they simply ask for "total power"?
Or can it be that it should be "useful power" instead of "general power"?

What you have is that the total power generated (which you calculated) consists of 2 parts.
One part that is dissipated in the circuit itself in a useful manner.
And one part that cannot be used, the part that is wasted as heat. That would be the part dissipated in the internal resistor of the battery.

Gold Member
Ohhhhhhhhhhhhhhhhhhhhh. So that's what they're asking, I think. Yea, you're right.

The previous one meant total power (I think. The word in exact translation from hebrew means "general", or "inclusive")

כללי

But I still think they meant total.

As for this question, then yes, they meant the dissipated power at the internal resistance! Brilliant

Thank you for helping me understand it, ILS!

You think I'm ready for the test now? I've attached all the problems from Term A (Hebrew though-- but I think just by looking at the circuit and the English SYMBOLS (not signs, SYMBOLS ) in the question ye'd be able to deduce it. Besides, we solved question 1 and 3 on the forum. Question 2 and 4 I did successfully on my own!

#### Attachments

• Electronic Test.pdf
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ehild
Homework Helper
No, they're asking for the voltage on the outside of the voltage source.
That is the original voltage reduced by the voltage across the internal resistance.

"It is terminal voltage": voltage measured across the terminals of a "loaded" source, that is a source which is connected into a circuit.

The voltage across the terminals of a source, not connected to anything, that is no current flows through it, is the "electromotive force (abbreviate: emf) usually denoted by E or ε.
If r is the internal resistance of the source

Uterminal=E-rI

"General power" can be "generator power" the power supplied by the source to the circuit = (terminal voltage )* (generator current).
ehild

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Gold Member
So my answer is still correct it's only a notation mishap?

I like Serena
Homework Helper
Yeah. I think you're ready for the test now.

Btw, what is the answer to the last question?

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I like Serena
Homework Helper
You rock! :)

Gold Member
You rock harder!!! Thanks! ^^