Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Electric Field and Potential
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Electric Field and Potential
Two charges of 2.0 × 10^ -6 C and -1.0 × 10^ -6 C are placed at a...
Two charges of and are placed at a separation of . Determine the position where a third charge will experience zero net force.
Options
- A from the larger magnitude charge on the side of the smaller magnitude charge
- B from the larger magnitude charge on the side of the smaller magnitude charge
- C from the larger magnitude charge between the two charges
- D from the larger magnitude charge on the side of the smaller magnitude charge
Correct answer
A. from the larger magnitude charge on the side of the smaller magnitude charge
Step-by-step solution
Let and .
The distance between the charges is .
For the net force on a third charge to be zero, the net electric field at that point must be zero. Since the charges have opposite signs, the neutral point lies on the line joining the charges, outside the region between them, and closer to the charge with the smaller magnitude ().
Let the neutral point be at a distance from on the side of . The distance of this point from is .
Equating the magnitudes of the electric fields produced by and at this point:
Taking the square root of both sides:
Rationalizing the denominator:
Using :
The position is from the larger magnitude charge on the side of the smaller magnitude charge.
The distance between the charges is .
For the net force on a third charge to be zero, the net electric field at that point must be zero. Since the charges have opposite signs, the neutral point lies on the line joining the charges, outside the region between them, and closer to the charge with the smaller magnitude ().
Let the neutral point be at a distance from on the side of . The distance of this point from is .
Equating the magnitudes of the electric fields produced by and at this point:
Taking the square root of both sides:
Rationalizing the denominator:
Using :
The position is from the larger magnitude charge on the side of the smaller magnitude charge.