Answer:
The observed wavelength on Earth from that hydrogen atom is
.
Explanation:
Given that,
The actual wavelength of the hydrogen atom, 
A hydrogen atom in a galaxy moving with a speed of, 
We need to find the observed wavelength on Earth from that hydrogen atom. The speed of galaxy is given by :

is the observed wavelength

So, the observed wavelength on Earth from that hydrogen atom is
. Hence, this is the required solution.
Answer:
I hope it's helpful for you ☺️
Answer:
When electric voltage is applied, an electric field within the metal triggers the movement of the electrons, making them shift from one end to another end of the conductor. Electrons will move toward the positive side.
Velocity = fλ
where f is frequency in Hz, and λ is wavelength in meters.
2.04 * 10⁸ m/s = 5.09 * 10¹⁴ Hz * λ
(2.04 * 10⁸ m/s) / (5.09 * 10¹⁴ Hz ) = λ
4.007*10⁻⁷ m = λ
The wavelength of the yellow light = 4.007*10⁻⁷ m