Question

In the apparatus shown below, a metal bar slides along two fixed metal bars which are connected at the other end with a resistor. The apparatus is surrounded by a constant B-field as shown.

 

4. What is the direction of the induced B-field in the apparatus as the bar moves?

Into the page

Out of the page

To the right

To the left

Zero

 

5 What is the magnitude and direction of the induced current?

Answer 1

4. The contour crossed by the magnetic field lines decreases ( \(d S<0\) in \(e=-\frac{\mathrm{d} \Phi}{\mathrm{d} t}\), with \(\Phi=B S\) ). Thus, \(\mathrm{B}_{\mathrm{i}}\) should have the same sense as \(\mathrm{B}\).

Answer A.

5. \(e=B l v=2.2 * 10^{-3} \mathrm{~V}\)

\(\mathrm{I}=\mathrm{e} / \mathrm{R}=5.5^{*} 10^{-4} \mathrm{~A}\)

The sense is from right to left through the sliding bar.

Answer D.