1)

 Two parallel wires in the plane of the paper are distance X0 apart. A point charge is moving with speed u between and wires in the same plane at a distance X1 from one of the wires. When the wires carry current of magnitude I in the same direction, the radius of curvature of the path of the point charge is R1. In contrast, if the currents in the two wires have directions opposite to each other, the radius of curvature of the path is R2. If   $\frac{X_{0}}{X_{1}}=3$ , and value of R1/R2 is


A) 4

B) 5

C) 2

D) 3

Answer:

Option D

Explanation:

$B_{2}=\frac{\mu_{0}I}{2\pi x_{1}}+\frac{\mu_{0}I}{2\pi(x_{0}-x_{1})}$

        { when  currents are in opposite directions)

$B_{1}=\frac{\mu_{0}I}{2\pi x_{1}}-\frac{\mu_{0}I}{2\pi(x_{0}-x_{1})}$

2132021632_m1.JPG

(when currents are in same direction)

Subtituting $x_{1}=\frac{x_{0}}{3}$ as \left(\frac{x_{0}}{x_{1}}\right)

$B_{1}=\frac{3\mu_{0}I}{2\pi x_{0}}-\frac{3\mu_{0}I}{4\pi x_{0}}=\frac{3\mu_{0}I}{4\pi x_{0}}$

    $R_{1}=\frac{mv}{qB_{1}} $   and  $ B_{2}= \frac{9\mu_{0}I}{4\pi x_{0}}$

 $R_{2}=\frac{mv}{qB_{2}} $

$\frac{R_{1}}{R_{2}}=\frac{B_{2}}{B_{1}}=\frac{9}{3}=3$