
Two long parallel conductors $X$ and $Y$ are placed vertically at a distance $d$ apart. Conductor X carries a current I upwards and conductor Y carries a current 21 downwards. A third long conductor Z is placed parallel to both X and Y and between X and Y . If Z carries a current I upwards and is at a distance $x$ from conductor X , then:
A. All the conductors are in equilibrium and the net force on Z is zero
B. The net force on Z is $\frac{\mu_0 I^2}{2 x \pi}\left[\frac{d+x}{d-x}\right]$ towards X
C. The net force on Z is $\frac{\mu_0 I^2}{2 x \pi}\left[\frac{d+x}{d-x}\right]$ towards Y
D. The net force on Z is $\frac{\mu_0 I^2}{2 x \pi}\left[\frac{d-x}{d+x}\right]$ towards Y
B
D
A
C
A $50 \Omega$ galvanometer is shunted by a resistance of $S \Omega$. If $8 \%$ of total current passes through the galvanometer, the value of $S$ is:
$4 \Omega$
$4.35 \Omega$
$3.9 \Omega$
$3.35 \Omega$

A current of 3 A enters one vertex P of an equilateral triangle PQR having three resistors of $1 \Omega$ each forming the sides of the equilateral triangle as shown. The value of $i_2$ in amperes is:
2 A
1.7 A
1 A
1.5 A
Current in a conductor is expressed as $I=8 t^3+3 t^2+2$, where current I is measured in amperes and time t is measured in seconds. What is the charge that flows through a cross-section of the conductor between time $t=1 \mathrm{~s}$ to $t=2 \mathrm{~s}$ ?
49 C
18 C
29 C
39 C
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