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A 20 cm long metallic rod is rotated with 210 rpm 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 0.2 T parallel to the axis exists everywhere. The emf developed between the centre and the ring is _____ mV. (Take π = 22/7)

Asked in JEE Main 15th April 1st Shift 2023 · Rotating rods, discs and wheels

Answer: 88

Step-by-step solution

ω=(2π×210)/(60)=22 rad s⁻¹.

ε=1/2Bωℓ²=1/2×0.2×22×(0.2)².

ε=0.088 V =88 mV.

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