Concepts Of Physics MCQ Edition [Volume 2]PhysicsMagnetic Field
A rigid wire consists of a semicircular portion of radius R and two straight sections. The wire is partially immersed in a perpendicular magnetic field B as shown in the figure. Determine the magnetic force on the wire if it carries a current i .
Options
- AZero
- B2 i R B , upward in the figure
- C2 i R B , downward in the figure
- Di R B , upward in the figure
Correct answer
B. 2 i R B , upward in the figure
Step-by-step solution
The magnetic force on a current-carrying wire in a uniform magnetic field is given by F = i( L _ eff B ) , where L _ eff is the displacement vector from the initial point to the final point of the wire in the magnetic field. The wire consists of two vertical straight sections and a semicircular section. The straight sections carry current in opposite directions (one upwards, one downwards). The magnetic forces on these straight sections are equal in magnitude and opposite in direction (pointing horizontally outward