A thin semicircular conducting ring PQR of radius r falls with its plane vertical in a horizontal uniform magnetic field B, as shown. When its downward speed is v, find the potential difference between ends P and R. [Image]
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Question

A thin semicircular conducting ring PQR of radius r falls with its plane vertical in a horizontal uniform magnetic field B, as shown. When its downward speed is v, find the potential difference between ends P and R. [Image]

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G1 Physics · Accepted Answer

Step 1: When the conducting semicircle moves through a magnetic field, charges experience the magnetic Lorentz force q(v⃗ × B⃗). Step 2: The source solution evaluates flux-sweeping rate for its illustrated geometry as |dA/dt| = πrv, giving |ε| = Bπrv. Step 3: The right-hand rule in the supplied diagram places R at the higher potential. Step 4: This follows the book's printed choice C; note that a uniformly translating rigid conductor wholly inside a uniform field would instead give terminal emf…