In a Fresnel biprism experiment, the two positions of lens given separation between the slits as 16 cm and 9 cm respectively. What is the actual distance of separation?a)10.5 cmb)13 cmc)12 cmd)14 cmCorrect answer is option 'C'. Can you explain this answer?

Question

Answer

Solution:

Given:
Separation between the slits in the Fresnel biprism experiment is 16 cm and 9 cm.

To find:
The actual distance of separation between the slits.

Let's assume:
The distance of separation between the slits to be 'd'.

Using the formula for the fringe width in the Fresnel biprism experiment:

w = λD / (d - D)

Where:
w is the fringe width,
λ is the wavelength of light used,
D is the distance between the lens and the screen,
d is the distance of separation between the slits.

1. For the first position of the lens:
Given that the separation between the slits is 16 cm, let's assume the fringe width to be w1.

w1 = λD / (d - D)

2. For the second position of the lens:
Given that the separation between the slits is 9 cm, let's assume the fringe width to be w2.

w2 = λD / (d - D)

Since the wavelength of light used and the distance between the lens and the screen are the same for both positions of the lens, we can equate the two equations:

w1 = w2

λD / (d - D) = λD / (d - D)

Canceling out the common terms, we get:

d - D = d - D

This implies that the actual distance of separation between the slits, 'd', is the same for both positions of the lens.

Therefore, the actual distance of separation between the slits is 16 cm.

Hence, the correct answer is option 'C' - 12 cm.

Top Courses for Physics

Suggested Free Tests

Related Content

Schools

Competitive Examinations

Quick Access Links

Technical Exams