An electrical cable of copper has just one wire of radius 9mm . Its resistance is 5 This single copper wire of the cable is replaced by 6 different well insulated copper wires each of radius 3mm . The total resistance of the cable will now be equal to

see full answer

Start JEE / NEET / Foundation preparation at rupees 99/day !!

21% of IItians & 23% of AIIMS delhi doctors are from Sri Chaitanya institute !!

An Intiative by Sri Chaitanya

7.5

270

answer is B.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Concept: We have given the electric cable of copper and its resistance and we need to calculate the total resistance of the cable
Let the resistance of single copper wire be

. If

is the specific resistance of copper wire, then

When the wire is replaced by six wires, let the resistance of each wire be

. Then

From equation (i) and (ii) , we get Question Image

These six wires are in parallel. Hence, the resistance of the combination would be

Hence, the correct option is 3.

Watch 3-min video & get full concept clarity

tricks from toppers of Infinity Learn

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET

🔥 Start Your JEE/NEET Prep at Just ₹1999 / month - Limited Offer! Check Now!

Get Expert Academic Guidance – Connect with a Counselor Today!

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Books for IIT JEE

Best Books for NEET