Question

A wire of resistance R1 is cut into five equal pieces. These five pieces of wire are then connected in parallel. If the resultant resistance of this combination be R2, then the ratio R1/ R2 is ?​

Answer 1

Answer:

25:1

Explanation:

The resistance R₁ is cut into five pieces.

The area of cross section remains same but the length decreases to its one - fifth.

Therefore, the resistance of each piece of the wire is one fifth of the total wire.

Rₓ = 0.2R₁

Given, R₂ is the resistance of the circuit when all of the pieces are connected in parallel

$\frac{1}{R2} = (\frac{1}{0.2R1})5\\\\\\\frac{1}{R2} = \frac{25}{R1}\\\\{R2} = \frac{R1}{25}$

R1:R2 =

$\frac{R1}{\frac{R1}{25} } \\= 25:1$

Answer 2

Here is the answer. See the above attachment.