Question

A wire length 10 cm and resistance 3 ohm is stretched to length 30 cm then its resistance will be?{1 ohm,27ohm,30 ohm}

Answer 1

here volume doesnt change so r is directly propotional to l^2

r=kl/a

multiply up and down we get r=kl^2/V

SO RESISTANCE IS 27 OHM