Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Magnetic Field due to a Current
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Magnetic Field due to a Current
Each battery shown in the figure has an emf equal to 5 V ....
Each battery shown in the figure has an emf equal to . Determine the magnetic field at the point for any set of values of the resistances.


Options
- AA non-zero constant independent of the resistances
- BDepends on the values of the resistances
- CCannot be determined without knowing the distance of point
- D
Correct answer
D.
Step-by-step solution
Let the potential at the bottom-middle junction be and at the top-middle junction be .
From the polarities of the batteries, the potential at the bottom-left node is and at the bottom-right node is .
Similarly, the potential at the top-left node is and at the top-right node is .
The potential difference across the left resistor is .
The potential difference across the middle resistor is .
The potential difference across the right resistor is .
Applying Kirchhoff's Current Law at the top nodes, the total current leaving through the resistors must be zero:
Since the resistances are positive, .
As the potential difference across each resistor is zero, no current flows in any branch of the circuit.
Since the current is zero everywhere, the magnetic field produced by the circuit at point is .
Answer:
From the polarities of the batteries, the potential at the bottom-left node is and at the bottom-right node is .
Similarly, the potential at the top-left node is and at the top-right node is .
The potential difference across the left resistor is .
The potential difference across the middle resistor is .
The potential difference across the right resistor is .
Applying Kirchhoff's Current Law at the top nodes, the total current leaving through the resistors must be zero:
Since the resistances are positive, .
As the potential difference across each resistor is zero, no current flows in any branch of the circuit.
Since the current is zero everywhere, the magnetic field produced by the circuit at point is .
Answer: