Question

A resistor of 25 cm length and 4 ohm is stretched to a uniform wire of 50 cm length. The resistance now is____.

(a).1 ohm
(b).12 ohm
(c).16 ohm
(d).20 ohm

pls give the correct explanation and answer...........if i am satisfied with your correct answer I will mark you as brainliest.......​

Answer 1

Answer:OPTION C

Explanation:AS THE WIRE IS SAME ,hence resistivity is same in both case

R=resistivity*length/area

as the wire have same volume before and after expansion

so,25*A1=50*A2  WERE A1 and A2 ARE area of wire before and after stretching respectively       since volume=area*length

A1/A2=2

LET 'X' BE THE UNKNOWN RESISTANCE,using the equation of resistance,

4/x=25/A1* A2/50

THUS,X=16 OHM