The external diameter of a 314 m long copper tube is 1.2 cm and the internal diameter is 1 cm. calculate its resistance if the specific resistance of copper is `2.2xx10^(-8)` ohm-metre.

Answer

A, D

Explanation

As `vec(p)_(1) + vec(p)_(2) = vec(0)` so `vec(p)_(1') + vec(p)_(2') = 0`
For (A) `vec(p)_(1') + vec(p)_(2') = (a_(1) + a_(2)) hat(i) + (b_(1) + b_(2)) hat(j) + c_(1) hat(k)`
For (B) `vec(p)_(1') + vec(p)_(2') = (a_(1) + a_(2)) hat(i) + (b_(1) + b_(2)) hat(j)`
For (C ) `vec(p)_(1') + vec(p)_(2') = (c_(1) + c_(2)) hat(k)`
For (D) `vec(p)_(1') + vec(p)_(2') = (a_(1) + a_(2)) hat(i) + 2b_(1) hat(j)`
But `a_(1'), b_(1'), c_(1'), a_(2), b_(2), c_(2) != 0`
Therefore (A) & (D) is not possible to get
`vec(p)_(1') + vec(p)_(2') = vec(0)`