# Stupid question sorry

1. Feb 1, 2005

### Grandor

This sounds like a stupid question. However my teacher didnt really explain it well.
Its my first day back at school, cut me some slack thx.

- Calculate the frequency of a lightwave of wavelengh 500nm. Travelling at speed of light (3x10^8 ms-1)
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I WILL SUBSITUTE LAMBDA for H (cause i dont know how to type it)

f = ?
h = 500nm
V = 3x10^8 ms-1.

So 500nm x 10^-9 = 0.0000005m

V = fh

Therefore f = h/V

0.0000005m / 3000 000 00ms = ???

Would that be 1.66666666666666666 x10^-15???

BTW- can someone tell me how to input equations?

2. Feb 1, 2005

### vincentchan

your algebra is not quite correct

3. Feb 1, 2005

### Grandor

err,
V = fXh
Divide out the f... f/V = h. So you would have to multiply out the V to get/

f = vh ??

0.0000005m x 3000 000 00ms = ???

so F=150? ?

4. Feb 1, 2005

### buddingscientist

V = fh

V/h = fh/h
V/h = f

from memory green light should have a freq around something x 10^14

5. Feb 1, 2005

### Grandor

6 x 10^14 perhaps?

How could i cock it up that much? TWICE! But I see the logic now.
Thankyou.

6. Feb 1, 2005

$$f = \frac{v}{\lambda}$$ where $$v$$ is speed and $$\lambda$$ is wavelength.