Two beams of light having intensities and interfere to produce a fringe pattern on a screen. The phase difference between the beams is at point and at point . Then the difference between the resultant intensities at and is

Question

Two beams of light having intensities $I$ and $4 I$ interfere to produce a fringe pattern on a screen. The phase difference between the beams is $π / 2$ at point $A$ and $π$ at point $B$ . Then the difference between the resultant intensities at $A$ and $B$ is [2001]

Smart Achievers · Accepted Answer

(2)

As we know, $4 I$

When phase difference is $π / 2$ ,

$I_{π / 2} = I + 4 I$ $\Rightarrow I_{π / 2} = 5 I$

Again, when $d$ phase difference is $π$ ,

$I_{π} = I + 4 I + 2 \sqrt{I} \sqrt{4 I} \cos π = I$

$∴$ $I_{π / 2} - I_{π} = 5 I - I = 4 I$

Solution

Q.
Two beams of light having intensities $I$ and $4 I$ interfere to produce a fringe pattern on a screen. The phase difference between the beams is $π / 2$ at point $A$ and $π$ at point $B$ . Then the difference between the resultant intensities at $A$ and $B$ is [2001]

1 $2 I$

2 $4 I$

3 $5 I$

4 $7 I$

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Solution

Q. Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the beams is π/2 at point A and π at point B. Then the difference between the resultant intensities at A and B is [2001]

1 2I

2 4I

3 5I

4 7I