How to Convert Cgs to SI Units for Flux and Energy Values?

In summary, the conversation was about converting values in different units to SI units. The first value mentioned was 10.7 mJy, which was thought to be 1.7*10^(-2)*10^(-26) but might be wrong. The second value, a flux value called kappa, was mentioned as 2 cm^2.g^(-1) and the conversion to meters and kilograms was thought to be 2*10^(-7) m2/kg, but it was pointed out that the grams conversion was incorrect. The correct conversion would be dividing by 10^(-3) instead of multiplying by it. It was also mentioned that the Jansky (Jy) is the unit for flux
  • #1
SorenaJ
5
0
Hi

I have a value that is 10.7 mJy, that I need to convert to SI units. I thought it would be 1.7*10^(-2)*10^(-26) but that might be wrong?

Then I have a flux value, kappa, of 2 cm^2.g^(-1) that needs to be converted to meters and kilogram. I thought it was 2*10^(-7) m2/kg, but that might be wrong as well. I would get the 10^(-4) from converting from cm2 to m2 and the 10^(-3) from converting from g to kg.

Can anyone help?
 
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  • #2
In the second part, you have the grams conversion wrong because it has a negative exponent. You should be dividing by 10^(-3), not multiplying by it.

I have no idea what a mJy is, but the 10^(-26) is a truly large factor.
 
  • #3
SorenaJ said:
Hi

I have a value that is 10.7 mJy, that I need to convert to SI units. I thought it would be 1.7*10^(-2)*10^(-26) but that might be wrong?

10.7 = 1.07 × 10

10.7 m = 10.7 × 10-3 = 1.07 × 10-2

Don't drop those zeroes!

BTW, this is the definition of the Jansky (Jy):

https://en.wikipedia.org/wiki/Jansky

1 Jy = 10-26 W / (m2-Hz)
 
  • #4
Thank you!
 

What is the difference between CGS and SI units?

CGS (centimeter-gram-second) and SI (International System of Units) are two systems of measurement used in science and engineering. The main difference between them is the base units they use. CGS uses the centimeter for length, the gram for mass, and the second for time, while SI uses the meter, kilogram, and second as base units for length, mass, and time, respectively.

Why do we need to convert from CGS to SI units?

While both systems are used in science and engineering, SI units are the standard units used internationally. Therefore, it is important to convert from CGS to SI units to ensure consistency and accuracy in scientific measurements and calculations.

What is the conversion factor for CGS to SI units?

The conversion factor for CGS to SI units depends on the specific unit being converted. For example, to convert from CGS to SI length units, you would multiply by 0.01, for mass units you would multiply by 0.001, and for time units you would multiply by 0.01.

How do I convert a value from CGS to SI units?

To convert a value from CGS to SI units, you would need to multiply the value by the appropriate conversion factor. For example, if you wanted to convert 5 cm to meters, you would multiply 5 by 0.01, resulting in 0.05 meters.

What are some common units that require conversion from CGS to SI?

Some common units that require conversion from CGS to SI include centimeters to meters, grams to kilograms, dynes to newtons, and ergs to joules. Other units, such as temperature, also require conversion, but use a different formula.

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