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A cylindrical rod of length 1 m and radius 1 m is connected across a 10 V source of negligible internal resistance. Its resistivity varies as rho = b*x (x measured from the left end, b a positive constant). Find the electric field (SI units) at a point P located 10 cm from the left end.

1. 1
2. 2
3. 3
4. 4

Correct answer: 2

Solution

Integrating E = (I b x)/A from 0 to 1 gives V = I b/(2A); solving for I and substituting at x = 0.1 gives E = 2 V/m.

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