Question

A long metal bar of $30cm$ length is aligned along a north south line and moves eastward at a speed of $10m{s}^{-1}$. A uniform magnetic field of $4.0T$ points vertically downwards. If the south end of the bar has a potential of $0V$, the induced potential at the north end of the bar is:

• A. $+12V$
• B. $-12V$
• C. $0V$
• D. $cannotbedeterminedsincethereisnotclosedcircuit$

Answer 1

The correct option is A $+12V$

induced emf $=Blv=12V$. It is induced in the northward direction by right hand rule(emf=$\overrightarrow{V}\times \overrightarrow{B}$ )
therefore if south end of pole has potential of $0V$, north end will have a potential of $12V$