The frequency of red light emitted by neon sign having wavelength  is
 is  .
.
Further Explanation:
Wavelength is defined as the distance between two successive highest points or it is the length traveled in one complete period for a periodic wave.
Frequency is defined as the number of waves passing through a point in a unit time and is inversely proportional to wavelength.
Red light is the part of visible light spectrum. It is electromagnetic in nature. It has a maximum wavelength and minimum frequency in a visible light spectrum and travels with the speed of  .
.
Neon emits mostly the red and green light but we can observe the visible spectrum in neon emission spectrum.
Given:
The wavelength of the red light is  .
.
Concept:
The relationship between wavelength and frequency given as:

Substituting  for
 for  and
 and  for
 for  in above expression, we get
 in above expression, we get

Thus, the frequency of red light emitted by neon sign having wavelength  is
 is  .
.
Learn more:
1. Volume of gas after expansion: brainly.com/question/9979757
2. Principle of conservation of momentum: brainly.com/question/9484203
3. Average translational kinetic energy: brainly.com/question/9078768
Answer Details:
Grade: College
Subject: Physics
Chapter: Optics
Keywords:
Wavelength, successive, highest, complete, period, wave, frequency, unit, time, inversely, proportional, red, light, neon, maximum, minimum, visible, spectrum, 690nm, 3*10^8 m/s, speed, electromagnetic, nature and part.