Question 312: Waves Optics

Question

A diffraction pattern is obtained using a beam of red light. If red light is replaced by blue light then

Accepted Answer

In the context of diffraction, when a beam of red light, which has a longer wavelength ($\lambda_{	ext{red}}$), is replaced by blue light, which has a shorter wavelength ($\lambda_{	ext{blue}}$), the effect on the diffraction pattern can be understood through the formula for the distance between successive maxima:
$ \beta = \frac{\lambda D}{a} $
Here, $\beta$ represents the distance between successive maxima, $\lambda$ is the wavelength of the light used, $D$ is the distance to the screen, and $a$ is the slit width. From the equation, it is clear that $\beta$ is directly proportional to the wavelength $\lambda$.
Since $\lambda_{	ext{blue}} < \lambda_{	ext{red}}$, when blue light is used, the value of $\beta$ decreases compared to when red light is used. Hence, the diffraction bands become narrower and more closely spaced together.

Answer

no change in diffraction pattern.

Answer

diffraction bands become narrow and crowded together.

Answer

diffraction bands become broader and farther apart.

Answer

bands disappear.

Waves Optics

A diffraction pattern is obtained using a beam of red light. If red light is replaced by blue light then

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