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If the uncertainties in position and mom...

If the uncertainties in position and momentum are equal, the uncertainty in the velocity is :

A

`sqrt((h)/(pi))`

B

`sqrt((h)/(2pi))`

C

`(1)/(2m)sqrt((h)/(pi))`

D

none of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to follow the steps outlined below: ### Step 1: Understand Heisenberg's Uncertainty Principle Heisenberg's uncertainty principle states that the product of the uncertainties in position (Δx) and momentum (Δp) cannot be smaller than a certain value: \[ \Delta x \cdot \Delta p \geq \frac{h}{4\pi} \] where \( h \) is Planck's constant. ### Step 2: Given Condition The problem states that the uncertainties in position and momentum are equal: \[ \Delta x = \Delta p \] ### Step 3: Substitute into the Uncertainty Principle Substituting Δx = Δp into the uncertainty principle gives us: \[ \Delta x \cdot \Delta x \geq \frac{h}{4\pi} \] This simplifies to: \[ (\Delta x)^2 \geq \frac{h}{4\pi} \] ### Step 4: Solve for Δx Taking the square root of both sides, we find: \[ \Delta x = \sqrt{\frac{h}{4\pi}} \] ### Step 5: Relate Momentum to Velocity Momentum (p) is related to velocity (v) by the equation: \[ p = mv \] where \( m \) is the mass of the object. The uncertainty in momentum (Δp) can be expressed in terms of the uncertainty in velocity (Δv): \[ \Delta p = m \Delta v \] ### Step 6: Substitute Δp Since we have Δp as Δx from the earlier step, we can write: \[ \Delta p = \sqrt{\frac{h}{4\pi}} = m \Delta v \] ### Step 7: Solve for Δv Now, we can solve for the uncertainty in velocity (Δv): \[ \Delta v = \frac{\Delta p}{m} \] Substituting Δp: \[ \Delta v = \frac{\sqrt{\frac{h}{4\pi}}}{m} \] ### Step 8: Simplify the Expression This can be simplified further: \[ \Delta v = \frac{1}{m} \sqrt{\frac{h}{4\pi}} = \frac{1}{2m} \sqrt{\frac{h}{\pi}} \] ### Final Result Thus, the uncertainty in velocity is: \[ \Delta v = \frac{1}{2m} \sqrt{\frac{h}{\pi}} \] ### Conclusion The correct answer is that the uncertainty in velocity is \( \frac{1}{2m} \sqrt{\frac{h}{\pi}} \). ---
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If uncertainty in position and momentum are equal then uncertainty in velocity is.

It is not possible to determine precisely both the position and momentum (or velocity) of a small moving particle such as electron, proton etc. This is known as Heisenberg uncertainty principle. The mathematical form of this principle is : Delta x.Delta p ge (h)/(4pi) (constant) However this principle is irrelevant in case of bigger particles such as a cup, ball, car etc., that we come across in our daily life. If uncertainty in position and momentum are equal, the v uncertainty in velocity would be

Knowledge Check

  • What will be the uncertainty in velocity of an electron when the uncertainty in its position is 1000 Å?

    A
    `5.79xx10^(2)ms^(-1)`
    B
    `5.79xx10^(8)ms^(-1)`
    C
    `5.79xx10^(4)ms^(-1)`
    D
    `5.79xx10^(-10)ms^(-1)`
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