# Planck's Constant Related to Velocity of Light?

1. Dec 28, 2008

### referframe

A few of the formulas that I have seen for calculating Planck's constant involve, amoung other things, dividing by the velocity of light. It appears as though the finiteness of the velocity of light and that Planck's constant is not zero are related. This would imply that QM and Special Relativity are related at a fundamental level. Comments? Thanks in advance.

2. Dec 28, 2008

### Staff: Mentor

Can you give an example or two?

3. Jan 3, 2009

### referframe

Please see the attached PDF file describing how to measure and compute Planck's constant, h, from LED's. Does not this imply that h and c are inversely related?

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4. Jan 4, 2009

### olgranpappy

no, they are independent fundamental constants.

5. Jan 4, 2009

### spidey

In the document, it is given that slope = hc/e.Then using slope,c and e we can find h.
My question is,for finding the slope itself we have to use h first.

Both h and c are just constants. we have so many equations in physics having constants in it. that doesn't mean constants are inter related or inter dependent? They don't change. That's why they are constants unless we change units.

6. Jan 4, 2009

### Staff: Mentor

The only reason c is in that equation is because in this experiment we use the wavelength of the light in the calculation, rather than its frequency. If we started out knowing or measuring the frequency of the light instead, c wouldn't appear in the calculation.