Question

Assertion (A): In Young’s double-slit experiment, the fringe width for dark and bright fringes is the same.

Reason (R): Fringe width is given by β = `(lambda D)/d`, where symbols have their usual meanings.

पर्याय

• Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

• Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).

• Assertion (A) is true, but Reason (R) is false.

• Both Assertion (A) and Reason (R) are false.

Answer 1

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Explanation:

In Young’s double-slit experiment (YDSE):

Fringe width (β) = `(lambda D)/d`

Bright and dark fringes are equally spaced.

In YDSE:

Distance between two consecutive bright fringes = β

Distance between two consecutive dark fringes = β

Hence, fringe widths are equal. The assertion is true.

The formula:

β = `(lambda D)d`

gives the constant spacing between successive fringes. This applies equally to bright and dark fringes. The reason is true.

The formula shows equal spacing, hence explaining the equivalence of bright and dark fringe widths. Hence, both Assertion and Reason are true, and Reason correctly explains Assertion.