A wire made of material A has resistance `R_1` another wire made of material B having P time the length and q times the radius of first wire has resistance `R_2` . If resistivity of B is r times that of A, then calculate`R_2//R_1` .

Explanation

To solve the problem, we need to find the ratio \( \frac{R_2}{R_1} \) where \( R_1 \) is the resistance of wire A and \( R_2 \) is the resistance of wire B.

### Step-by-Step Solution:

1. **Understanding the Resistance Formula**:
The resistance \( R \) of a wire is given by the formula:
\[
R = \frac{\rho L}{A}
...