Question

7. The hydrogen spectrum has a red line at 656 nm and the helium spectrum has a red line at 668 nm. Calculate the frequency of each line and hence find the difference in the frequencies.​

Answer 1

First, calculate the frequency of the red line of hydrogen:

Frequency = c/λ

= (3 x 10^8 m/s) / (656 x 10^-9 m)

= 4.58 x 10^14 Hz

Then, calculate the frequency of the red line of helium:

Frequency = c/λ

= (3 x 10^8 m/s) / (668 x 10^-9 m)

= 4.49 x 10^14 Hz

Lastly, calculate the difference in frequencies between hydrogen and helium:

Difference = (4.58 x 10^14 Hz) - (4.49 x 10^14 Hz)

= 9.0 x 10^12 Hz