. The masses of three copper wires are in the ratio


1:3:5 and their lengths are in the ratio 5:3:1 . The ratio of their resistance is

A: 15:1:125

B: 1:125:15

C: 125:1:15

D: 125:15:1

Best Answer

Explanation:

Resistance is given by

R = pl /A = PL2/V (A=V/L)

= PdL2/ m(V=m/d)

It is given that the three wires are of same material,

so density and resistivity will be same of all the wires.

So,

R∝ L2 / m

Now, let

M1:M2:M3=1:3:5

L1:L2:L3 =5:3:1

So

R1:R2:R3= L21/m1:L22/m2:L23/m3

=52/1:32/3:12/5

=125:15:1

So, option (D) is correct.

Final Answer:

Hence, option (D) is correct. ( 125:15:1 ) 

 

 

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