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In biprism experiment, the distance of 20th bright band from the central bright band is 1.2 cm. Without changing the experimental set-up, the distance of 30th bright band from the central bright band - Physics

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Question

In biprism experiment, the distance of 20th bright band from the central bright band is 1.2 cm. Without changing the experimental set-up, the distance of 30th bright band from the central bright band will be ______.

Options

  •  0.6 cm

  • 0.8 cm

  • 1.2 cm 

  • 1.8 cm

MCQ
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Solution

In biprism experiment, the distance of 20th bright band from the central bright band is 1.2 cm. Without changing the experimental set-up, the distance of 30 bright band from the central bright band will be 1.8 cm.

Explanation:

Given:

X20 = 1.2 cm, X30 = ?

For nth bright band `x_n = (Dnlambda)/d`

For 20th bright band `x_20 = 20(Dnlambda)/d`    ...(1)

For 30th bright band `x_30 = 30(Dnlambda)/d`    ...(2)

Dividing equation (2) by equation (1)

`x_30/x_20 = 30/20`

∴ `x_30 = x_20 xx 3/2`

= `1.2 xx 3/2`

= 1.8 cm

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