Question

A conducting loop in the plane of the paper is halfway into the magnetic field (which points into the page). If the magnetic field begins to increase rapidly in strength, what happens to the loop?

• A. The loop is pushed upwards, towards the top of the page.
• B. The loop is pushed to the right, out of the page.
• C. The loop is pulled to the left towards the magnetic field.
• D. The loop is pushed downwards, towards the bottom of the page

Answer 1

The Correct Option is B

When the magnetic field (which is pointing into the page) increases in strength, it induces an electromotive force (EMF) and current in the loop according to Faraday's Law of electromagnetic induction.
Using the right-hand rule, the induced current in the loop will circulate counterclockwise to oppose the change in the magnetic field. This means that on the left half of the loop (the half inside the magnetic field), the current is directed downwards. 
Lorentz's force on a current-carrying wire in a magnetic field is given by \(( F = I \times L \times B ),\) where I  is the current, L  is the length of wire, and B is the magnetic field. Again using the right-hand rule, the force on the left half of the loop (the half inside the magnetic field) due to the downward current and the magnetic field pointing into the page will be directed to the right, pushing the loop out of the magnetic field. 
So, the correct answer is: B. The loop is pushed to the right, out of the page.