Question

two wires made of german silver are taken such that the length and area of cross section of the second wire r twice and thrice respectively those of the first wire. if the resistance of the second wire is 12r. find the resistance of the first wire??????<br /><br />10 points plz answer fast exam tomorrow

Answer 1

Answer:

18 ohms

Here is the explanation : -

Answer 2

Given,

Two german silver Wires of a given length, area of cross-section, and resistance

To Find,

Resistance of the second  wire,

Solution,

Let the length of the first wire = $l$,

Area of cross-section = $A$,

Resistance = $R$,

Length of second wire = $l1$,

Area of cross-section = $A1$,

Resistance = $R1$ = 12r,

According to the question,

$l1=2l,\\A1=3A,$

$R=p\frac{l}{A}$,

$\frac{R}{R1} = \frac{l1}{l}\frac{A}{A1}$,

Upon solving the equation,

R = 8r,

Henceforth, Resistance of second wire = 8r.