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Question
A 1.0 m long metallic rod is rotated with an angular frequency of 400 rad s−1 about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field of 0.5 T parallel to the axis exists everywhere. Calculate the emf developed between the centre and the ring.
Solution
Length of the rod, l = 1 m
Angular frequency, ω = 400 rad/s
Magnetic field strength, B = 0.5 T
One end of the rod has zero linear velocity, while the other end has a linear velocity of lω.
Average linear velocity of the rod, `"v" = ("l"omega + 0)/2`
= `("l"omega)/2`
Emf developed between the centre and the ring,
e = Blv
= `"Bl"(("l"omega)/2)`
= `("Bl"^2omega)/2`
= `(0.5 xx (1)^2 xx 400)/2`
= 100 V
Hence, the emf developed between the centre and the ring is 100 V.
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