Question

Assertion: In Young’s double slit experiment, the first bright band for blue light is closer to the centre than the first bright band for green light.

Reason: Blue light has a longer wavelength than green light.

Options

• Both Assertion and Reason are true and Reason is the correct explanation for Assertion.

• Both Assertion and Reason are true but Reason is not the correct explanation for Assertion.

• Assertion is true and Reason is false.

• Assertion is false and Reason is true.

Answer 1

Assertion is true and Reason is false.

Explanation:

In Young’s Double Slit Experiment (YDSE), the distance of a bright fringe from the center (y) is directly proportional to its wavelength (λ), as shown by the formula: 

y = `(nλD)/d`

Since blue light has a shorter wavelength than green light (λ_blue < λ_green), its first bright band will be closer to the center.

In the visible spectrum (VIBGYOR), wavelength increases from violet to red. Therefore, blue light has a shorter wavelength than green light, not a longer one.