Question

this is the information i was given, it is confusing since the teacher didnt explain it at all...
- speed of light = 3x10^8 m/s
- 1nm= 10^-9 m

the problem i have to solve is...
A laser has a wavelength of 2.5 nm. What is the frequency in Hz? (Type your response in scientific notation as #E# Hz such as 5 x 10^-5 Hz would be 5E-5 Hz)

also i dont known what sientific notation is... and he refuses to help me until ice tried the problem at least 4 times. i dont know where to begin.

Answer 1

If you are paying that teacher, stop it. Honestly, I have difficulty believing you. You absotely need to master scientific notation, it does not take a rocket scientist to master it.
1000=1*10³=1E3 (more often, a little e is used)
4.5E2=450
https://www.chem.tamu.edu/class/fyp/mathrev/mr-scnot.html

Now your problem (all done in ScientificNotation)
the wave equation; frequency*wavelength=speed of light
frequency=speedlight/wavelength=(3e8 m/s )/(2.5e-9 m)
now you have to remember, the rules for exponents
x^a/x^b)=x^a-b so
3e8/2.5e-9=(3/2.5 ) e^17 Hz=1.2e^17 hertz

Answer 2

WL = wavelength,
WL = V * T = V * (1/F) = 3*10^8 * (1/F) = 2.5*10^-9 m,
3*10^8/F = 2.5*10^-9,
F = 1.2*10^17 Hz. = 1.2e17 Hz.