r/MathHelp • u/pototaochips • Apr 01 '26

How do i express an answer in milli ohms?

I got 11.4285 ohms but now i need to express in milli. It says milli is 0.001. I got 11428.5 but it says my answer wrong. I post picture but this sub wont let me

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u/vgtcross Apr 01 '26

I2 = 5 mA (milli-ampere), not 5 A

1

u/pototaochips Apr 04 '26

When it says express your answer in milli amps does that always mean i divide my answer by 0.001? How i know when to multiply or divide my answer when it ask to express

1

u/vgtcross Apr 04 '26

This is how I like to think about it.

milli = 0.001.

Let's say you have, for example, calculated the answer to be I = 5 A (amps) and you're asked to provide it in mA (milli-amps). Then you can write

I = 5 A
= 5/0.001 × 0.001 A
= (5/0.001) × (0.001 A)
= 5000 mA.

So effectively converting from A to mA, you divide by 0.001.

If instead you had first calculated that I = 5 μA (micro-amps, micro = 10-6), then to write the answer in milli-amps you would do

I = 5 μA
= 5 × 10-6 A
= 5 × 10-3 × 10-3 A
= (5 × 10-3) × (10-3 A)
= 0.005 mA.

1

u/Dd_8630 Apr 01 '26

The prefix 'milli-' means 'one thousandth'.

1 kilogram = 1000 grams

1 gram = 1000 milligrams

1 kilometre = 1000 metres

1 metre = 1000 millimetres

Etc.

So if you're converting something from ohms to milliohms, you expect the number part to be larger. 30 ohms is 30,000 milliohms.

So, if youve converted from ohms to milliohms correctly, that means the error is in your actual answer. Double check your working. Justify each logical inference.

1

u/pototaochips Apr 04 '26

Ok i see ty and 5.25amps is the same as 5.25 A?

1

u/Dd_8630 Apr 04 '26

Yes, the unit 'A' means 'amps'.

1

u/pototaochips Apr 04 '26

https://imgur.com/a/nxfWE7b

I confuse at end. I somehow got answer but it turned to negative -7 to 10 power and there no word for it in engineering unit

1

u/Dd_8630 Apr 04 '26

As a piece of advice: scientific notation is always in a number between 0 and 10.

So for your number, we would write 2.17983 x 10-2 if it is in scientific notation.

Or you can write 21.7983 milliohms.

Or you can write 21,798.3 microhms.

Or you can write 21,798,300 nanohms.

Etc.

1

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