A conducting rod `AC` of length `4l` is rotated about point `O` in a uniform magnetic field `vec(B)` directed into the plane of the paper. `AO = l and OC = 3l`. Find `V_(A) - V_(C)`.

Options

A. `V_(A)-V_(o)=(Bomegal^(2))/(2)`
B. `V_(o)-V_(C)=(7)/(2)Bomegal^(2)`
C. `V_(A)-V_(c)=4Bomegal^(2)`
D. `V_(c)-V_(o)=(9)/(2)Bomegal^(2)`

Answer

C

Explanation

By using `e=(1)/(2)Bl^(2)omega`
For `AO,e_(oA)=e_(O)-e_(A)=(1)/(2)Bl^(2)omega`
For part `OC,e_(OC)=e_(O)-e_(C)=(1)/(2)B(3l)^(2)omega`
`:.e_(A)-e_(C)=4Bl^(2)omega`