Question

Colour of light depends upon
(A) Wavelength
(B) Speed of light
(C) Both (A) and (D)
(D) Frequency

Answer 1

Hint We will find that colour of light depends upon which wavelength or speed of light or frequency or both wavelength and frequency. For this we will first understand what is visible light and how it contains different wavelengths.
After that we will understand how light is emitted by an object and how it is dependent on wavelength and absorption of colours and reflection of colours.
Then we will understand the relation between wavelength and frequency and then we will find out whether the colour of light is dependent upon frequency or not.
Then we will be able to choose the correct option.

Complete step by step solution
So, we first understand visible light, it is the small part within the electromagnetic spectrum that human eyes are sensitive to and can detect.
Visible light waves consist of different wavelengths. The colour of visible light is dependent on its wavelength. These wavelengths range from 700nm at the red end of the spectrum to 400nm at the violet end.
Now we understand how an object emits colour. Objects appear different colours because they absorb some colours (wavelength) and reflect or transmit other colours. The colours that we see are the wavelengths that are reflected or transmitted by the object.
So by the above concept we can understand that colour of light depends upon wavelength. Also the wavelength and frequency of light are closely related. The higher the frequency,the shorter the wavelength.
The equation that relates wavelength and frequency for electromagnetic waves is: $$\lambda \nu =c$$ where $$\lambda$$ is the wavelength, v is the frequency and c is the speed of light.
So by these we can say that colour of light depends upon wavelength and frequency both.

Hence option C is correct.

Note Always be careful that more than one option can be correct, so we have seen all the options.
Also remember that red light has the greatest frequency in the optical range and can be seen from a far distance, that’s why ambulance, traffic lights use red light.
The colour of visible light depends on its wavelength. These wavelengths range from 700nm at the red end of the spectrum to 400nm at the violet end.