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When the positively charged hanging pend...

When the positively charged hanging pendulum bob is made fixed, the work done in slowly shifting a unit positive charge from infinity to P is V. If the pendulum is free to move, the corresponding work done id `V'`. Then.

A

`V = V'`

B

`V gt V'`

C

`V lt V'`

D

`V le V'`

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AI Generated Solution

The correct Answer is:
To solve the problem, we need to establish a relationship between the work done in bringing a unit positive charge from infinity to a point P when a positively charged pendulum bob is fixed (denoted as \( V \)) and when the pendulum bob is free to move (denoted as \( V' \)). ### Step-by-Step Solution: 1. **Understanding the Fixed Pendulum Case:** - When the pendulum bob is fixed, it has a positive charge \( +Q \). - The work done \( V \) in bringing a unit positive charge \( +1 \) from infinity to point \( P \) is given by the formula for electric potential energy: \[ V = \frac{k \cdot Q \cdot 1}{r} \] - Here, \( k \) is Coulomb's constant, \( Q \) is the charge of the pendulum bob, and \( r \) is the distance from the charge to point \( P \). 2. **Understanding the Free Pendulum Case:** - When the pendulum bob is free to move, it will experience a repulsive force due to the positive charge \( +Q \). - This repulsion will cause the pendulum to move away from point \( P \), increasing the distance from \( r \) to \( r' \) (where \( r' > r \)). - The work done \( V' \) in this case is: \[ V' = \frac{k \cdot Q \cdot 1}{r'} \] 3. **Comparing the Two Cases:** - Since \( r' > r \), it follows that: \[ \frac{1}{r'} < \frac{1}{r} \] - Therefore, we can conclude: \[ V' < V \] - This implies that the work done \( V' \) when the pendulum is free to move is less than the work done \( V \) when it is fixed. 4. **Final Relationship:** - The final relationship we establish is: \[ V > V' \] ### Conclusion: The work done in bringing a unit positive charge from infinity to point \( P \) when the pendulum bob is fixed is greater than the work done when the pendulum bob is free to move.

To solve the problem, we need to establish a relationship between the work done in bringing a unit positive charge from infinity to a point P when a positively charged pendulum bob is fixed (denoted as \( V \)) and when the pendulum bob is free to move (denoted as \( V' \)). ### Step-by-Step Solution: 1. **Understanding the Fixed Pendulum Case:** - When the pendulum bob is fixed, it has a positive charge \( +Q \). - The work done \( V \) in bringing a unit positive charge \( +1 \) from infinity to point \( P \) is given by the formula for electric potential energy: \[ ...
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