An electrical cable of copper has just one wire of radius 9 m m and its resistance is 5 Ω . This single copper wire of cable is replaced by 6 different well-insulated copper wires, each of radius 3 m m . The total resistance of cable will now be equal to

Question

An electrical cable of copper has just one wire of radius 9 m m and its resistance is 5 Ω . This single copper wire of cable is replaced by 6 different well-insulated copper wires, each of radius 3 m m . The total resistance of cable will now be equal to, 7.5 Ω, 45 Ω, 90 Ω, 270 Ω

MARKS App · Accepted Answer

R ∝ 1 r 2 ∵ R a d i u s 9 m m ⟶ 3 m m ⇒ R e s i s t a n c e 5 Ω ⟶ 45 Ω R e s u l t o f s i x p a r a l l e l w i r e s = 45 6 = 7.5 Ω

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