Question

The thinnest bubble film in air that can possibly strongly reflect red light because of constructive interference makes up a certain buddle.
How could we create the thinnest bubble film that will strongly reflect purple light?
(A) Use a thicker film than the film used for the “red” bubble
(B) Use a film with a higher index of refraction than the film used for the “red” bubble
(C) Makes a bubble larger than the “red” bubble
(D) Make the bubble smaller than the “red” bubble
(E) Use a thinner film than the film used for the “red” bubble

Answer 1

Hint: We know that wavelength is the distance between identical points (adjacent crests) in the adjacent cycles of a waveform signal propagated in space or along a wire. In wireless systems, this length is usually specified in meters (m), centimetres (cm) or millimetres (mm). Wavelength is one way of measuring the size of waves. It is the distance between two corresponding points on adjacent waves, usually measured in meters. The wavelength of a transverse wave can be measured as the distance between two adjacent crests.

Complete step-by step answer:
We know that as the full spectrum of visible light travels through a prism, the wavelengths separate into the colours of the rainbow because each colour is a different wavelength. Violet has the shortest wavelength, at around 380 nanometres, and red has the longest wavelength, at around 700 nanometres.
We know that wavelength and frequency are inversely related so that longer waves have lower frequencies, and shorter waves have higher frequencies. In the visual system, a light wave's wavelength is generally associated with colour, and its amplitude is associated with brightness.
We know that to obtain a nice coloured pattern, the thickness of the film has to be similar to the wavelength of light and the bubbles are darkest where they are thinnest.

Hence, the correct answer is Option A.

Note: We know in physics, interference is a phenomenon in which two waves superpose to form a resultant wave of greater, lower, or the same amplitude. Interference effects can be observed with all types of waves, for example, light, radio, acoustic, surface water waves, gravity waves, or matter waves. Interference occurs when two waves of the same frequency are simultaneously present at the same place and are coherent. The two waves combine to form a single wave whose intensity depends not only on the intensities of the two individual waves, but also on the phase difference between them.
It should be known to us in places where the waves are out of step, destructive interference will occur, cancelling the reflected light (and the colour). If the crests of one of the waves coincide with the crests of the other, the amplitudes are additive. If the amplitudes of both waves are equal, the resultant amplitude would be doubled.