Question

How does the resistance of a wire change when the diameter is tripled ?

Answer 1

we know that resistance is inversly proportional to area of cross section so if diameter is thribled,

let diameter at first be d radius be r length be l and resistivity which is a constant be p.after thribled, everythings same exept radius which becomes 3/2r when d2 is 3d

d=2r thats why

now, R1=Pl/pie(r^2)

R2=Pl/(pie)(r^2)(9/4)=Pl/pie(r^2) x4/9

=>R2=R1(4/9)

so resistance changes by 4/9 times. CHEERS

if yr satisfied let me know