Calculating current

I don't understand what to do with this and also is that a lower-case delta? If so, what does it mean?

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(edited 9 years ago)

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Reply 1

uberteknik

Original post by goodwinning

ImageUploadedByStudent Room1422265584.023671.jpg

I don't understand what to do with this and also is that a lower-case delta? If so, what does it mean?

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Resistance is measure in ohms and is always denoted by omega.

The symbol in the question looks like a very stylised (unusual) upper case omega, I have never seen it in quite that form before.
The symbol for resistance is always

\Omega

.

The question asks you to use logarithms which implies an exponential term is stated somewhere else in the problem. Is this part of an exponential decay or rise or perhaps in the context of a time constant?

Current I is simply 25/8 = 3.125 amperes.

Post the whole question so that the context can be understood and I can give a better answer. :smile:

(edited 9 years ago)

Reply 2

jonathanemptage

Original post by goodwinning

I don't understand what to do with this and also is that a lower-case delta? If so, what does it mean?

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this is basic ohms law I is currant V is voltage band R is resistance youve had the equation V=IR transposed for you already you have V and you have R once you have worked out I the other equations to use are

V=IR
R=V/I
to check your work.

ps I have a degree in electronic engineering.

Reply 3

genson

I know how to use Ohm's law but it's the other parts of the problem I don't understand like how to solve this using logarithms and that weird symbol (which has now been sort of explained).That's why I'm so confused what to do because it also says use logarithms and I don't even know how that's possible with the information given.

By the way, that is the whole question.

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Reply 4

uberteknik

Original post by goodwinning

Without the wider context, it cannot be answered with anything other than an assumption of ohms law.

Is this question from a text book? If so which?

Reply 5

genson

It's part of an assignment that I have to do for my course: I'm doing a BTEC level 3 in applied science. It's really annoying me because if I don't get all the answers in this assignment correct I won't get a distinction in the maths unit which is really important for me to get into uni.

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Reply 6

uberteknik

Original post by goodwinning

I found the symbol, it's from the Microsoft 'Windings' font set and is used in astrology as the symbol for the Leo starsign.

Looks highly likely they used it in error and it's meant to be omega.

What is the maths question you are struggling with? It may make more sense to post it in here if it's physics based.

Reply 7

Stonebridge

Original post by goodwinning

If it's "part of" an assignment it may be helpful if you could provide the rest of the context for this as it makes no sense on its own.
Please post the text/diagrams/instructions of the assignment leading up to this question.

Reply 8

genson

Original post by Stonebridge

All the other questions in the assignment have nothing to do with this one and what I've posted is all I was given to work with for this problem, hence why I got very stuck despite all my attempts to try and research similar problems and had to resort to posting it on here for any suggestions.

There are no other text/diagrams/instructions. I'm not stupid enough to ask for help on a forum and not provide all the information I was given.

I have asked my brother, who is an electrical engineer, how to do this and he can't make sense of how to solve this with logarithms either and nor can my friends who are studying engineering.

Seems to me that this problem simply doesn't make sense and I'll just have to complain about it to my teacher.

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Reply 9

genson

ImageUploadedByStudent Room1422287012.996808.jpg

That's the assignment I was given.

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Reply 10

genson

Original post by goodwinning

That's the assignment I was given and that was it. We weren't even provided with any resources on how to solve these either.

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Reply 11

Stonebridge

It looks to me that Task 7 is just an exercise in using logarithms.

For part 7.2 find the logs of the two numbers, subtract (log 25 - log 8) and then find the antilog of the result.
Check the answer by doing the calculation directly =25/8

It's not really much to do with Ohm's Law. Just division using logs.

(edited 9 years ago)

Reply 12

uberteknik

Original post by goodwinning

That's the assignment I was given.

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Stonebridge hits the nail on the head in his post #12.

I deleted my last answer out of embarrassment. :colondollar:

I hate you Stonebridge! LOL :tongue:

Spoiler

Reply 13

Stonebridge

Original post by uberteknik

Stonebridge hits the nail on the head in his post #12.

I deleted my last answer out of embarrassment. :colondollar:

I hate you Stonebridge! LOL :tongue:

Spoiler

Ha. Ha.
I've altered my answer slightly as I had the numbers in the fraction for I = V/R the wrong way round.

:colondollar:

Spoiler

Reply 14

genson

Yeah, thanks a lot Stonebridge! 😄

It actually occurred to me in the beginning that you just might need to apply the logarithm law to it but when I was told (by a teacher no less) that symbol was a lower-case delta it threw me off. Still can't believe they put an astrology sign there.

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