IB Physics Magnetic flux through a loop
/This tutorial sheet studies the magnetic flux through a circular loop. This was a Paper 2 question in Zone 3 in May 2025.
What is the meaning of the term magnetic flux?
A constant current I flows in a long straight wire. Write down an expression for the magnetic field at a perpendicular distance r from the wire.
A small circular loop of radius R is in the plane of the wire with its centre at a distance r from the wire. Write down an expression for the magnetic flux through the loop. What assumption are we making?
If I=2.0 A, r=10.0 cm and R = 2.0 cm show that the magnetic flux through the loop is approximately 2.5x 10-8 Wb. This assumes that a constant magnetic field acts through the coil. In a show that question all substitution, rearranging and cancellations must be shown. Give the answer to one more decimal place to show evidence of calculator usage.
In question 4 determine the magnetic flux through the coil if the variation of field strength through the coil with distance from the straight wire is included. In this case there is slightly more flux through the coil since the magnetic field is stronger in the side of the loop closest to the straight wire. Flux = 2.54 x 10-8 Wb.
