Concepts Of Physics MCQ Edition [Volume 2]
- Exam
- Concepts Of Physics MCQ Edition [Volume 2]
- Subject
- Physics
- Chapter
- Magnetic Field
Concepts Of Physics MCQ Edition [Volume 2] · Physics · Magnetic Field
A 2 A current enters at the corner d of a square frame abcd having...
A current enters at the corner of a square frame having a side length of and exits at the opposite corner . A magnetic field is present in the region, directed perpendicular to the plane of the frame as shown in the figure. Determine the magnitude and direction of the magnetic forces acting on the four sides of the frame.

Options
- A on each wire; on and towards right, and on and upward
- B on each wire; on and towards left, and on and downward
- C on each wire; on and towards left, and on and downward
- D on each wire; on and towards right, and on and upward
Correct answer
B. on each wire; on and towards left, and on and downward
Step-by-step solution
The total current entering the square frame at corner is .
Since the frame is a square made of uniform wire, the resistance of the path is equal to the resistance of the path . Therefore, the current splits equally into the two branches.
Current in each side of the frame is:
The magnetic field is uniform, directed perpendicular to the plane of the frame and outwards (indicated by dots), so .
The magnitude of the magnetic force on each wire of length is given by:
The direction of the force on each wire can be found using :
For wire : Current is downwards (). (towards left).
For wire : Current is downwards (). (towards left).
For wire : Current is rightwards (). (downward).
For wire : Current is rightwards (). (downward).
Thus, the force is on each wire; on and towards left, and on and downward.
Since the frame is a square made of uniform wire, the resistance of the path is equal to the resistance of the path . Therefore, the current splits equally into the two branches.
Current in each side of the frame is:
The magnetic field is uniform, directed perpendicular to the plane of the frame and outwards (indicated by dots), so .
The magnitude of the magnetic force on each wire of length is given by:
The direction of the force on each wire can be found using :
For wire : Current is downwards (). (towards left).
For wire : Current is downwards (). (towards left).
For wire : Current is rightwards (). (downward).
For wire : Current is rightwards (). (downward).
Thus, the force is on each wire; on and towards left, and on and downward.