How would i find the energy of a spectral line?

Question

for Helium, where my wavelengths were 450 nm, 510 nm, 560 nm, 620 nm, 640 nm, and 650 nm. I am supposed to use the following equations;
Energy(j)=planck's constant x frequency(Hz)
and
Velocity(m/sec)=wavelength(m) x frequency(hz)

Answer 1

First use-: Velocity = Wavelength x Frequency to work out the frequency for each wavelength....

So you use-: Frequency = Speed of Light / Wavelength

450nm has frequency 6.6666667 x 10^14 Hz

510nm has frequency 5.88235 x 10^14 Hz

and so on.....

The shove the frequency in the other equation-:

Energy = Plank Const. x Frequency

(Plank const. = 6.63 x 10^-34 Js)

You should notice that the higher the frequency the more energy that photon has.

So for 450nm, we have frequency of 6.666667 x 10^14 Hx

E = 6.63 x 10^-34 x 6.666667 x 10^14 = 4.42 x 10^-19 Joules or 2.763 Electron Volts.

Just do the same for the rest.
If you want to convert Joules to Electron Volts, divide the amount of Joules by 1.6 x 10^-19 (the charge on the electron.)

Answer 2

E = energy, f = frequency, C (or V) = velocity, L = wave length

Now E = h*f (h = planks const)--------(1)
given, V = L*f => f =V/L, replacing V by velocity of light C:-
f = C/L, substituting this, f, in eqn(1)
E = (hC)/L,
u know h, L & C = 3x10^8 m/s
Now put the values get the answer

Answer 3

not sure exactly

was never that strong at Physics

It looks to me , at first glance like you could plug in Plank's constant and find it.

also, I'm pretty sure the speed of light is the same for all colors of light

speed is gonna be cycles per second (Hertz) Hz
maybe thats why Plank has a constant

worth some thinking about I think

Answer 4

The simple equation for this problem:
E = hc/(lamda) = h x (Mu)
Lamda: the wavelength
Mu: the frequency

Answer 5

mno