A fixed horizontal wire carries a current of $200\, A$. Another wire having a mass per unit length ${10^{ - 2}}\,kg/m$ is placed below the first wire at a distance of $2\, cm$ and parallel to it. How much current must be passed through the second wire if it floats in air without any support? What should be the direction of current in it
A$25\,A$ (direction of current is same to first wire)
B$25\,A$ (direction of current is opposite to first wire)
C$49\, A$ (direction of current is same to first wire)
D$49\, A$ (direction of current is opposite to first wire)
Medium
Download our app for free and get started
C$49\, A$ (direction of current is same to first wire)
c (c) For floating the second wire
$\left| \begin{array}{l}\,{\rm{Down}}\;{\rm{ward}}\;{\rm{weight}}\,\\\;\;{\rm{of}}\;{\rm{second}}\;{\rm{wire}}\end{array} \right| = \left| \begin{array}{l}\,{\rm{Magnetic}}\;{\rm{force}}\,\\\;\;\;\;\;{\rm{on}}\;{\rm{it}}\end{array} \right|$
$ \Rightarrow mg = \frac{{{\mu _0}}}{{4\pi }}.\frac{{2{i_1}{i_2}}}{a} \times l$
$ \Rightarrow \left( {\frac{m}{l}} \right)g = \frac{{{\mu _0}}}{{4\pi }}.\frac{{2{i_1}{i_2}}}{a}$
$ \Rightarrow {10^{ - 2}} \times 9.8 = {10^{ - 7}} \times \frac{{2 \times 200 \times i}}{{2 \times {{10}^{ - 2}}}} \Rightarrow i = 49\,A$
(Direction of current is same to first wire)
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
In a region, steady and uniform electric and magnetic fields are present. These two fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be a
A closely wound solenoid of $2000$ $turns$ and area of cross-section $1.5 \times 10^{-4}\ m^2$ carries a current of $2.0\, A.$ It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field $5 \times 10^{- 2}$ $tesla$ making an angle of $30^o $ with the axis of the solenoid. The torque on the solenoid will be
A rectangular coil (Dimension $5\,cm\times 2\,cm$ ) with $100\,turns,$ carrying a current of $3\,A$ in the clock-wise direction, is kept centered at the origin and in the $X-Z$ plane. A magnetic field of $1\,T$ is applied along $X-$ axis. If the coil is tilted through $45^o$ about $Z-$ axis, then the torque on the coil is.....$Nm$
An electron enters the space between the plates of a charged capacitor as shown. The charge density on the plate is $\sigma $. Electric intensity in the space between the plates is $E$. A uniform magnetic field $B$ also exists in that space perpendicular to the direction of $E$. The electron moves perpendicular to both $\vec E$ and $\vec B$ without any change in direction. The time taken by the electron to travel a distance $\ell $ is the space is
The current flowing through a coil of resistance $900\, ohms $ is to be reduced by $90\,\%$. What value of shunt should be connected across the coil ............. $\Omega $
Figure shows a conducting loop $A D C A$ carrying current $i$ and placed in a region of uniform magnetic field $B_0$. The part $A D C$ forms a semicircle of radius $R$. The magnitude of force on the semicircle part of the loop is equal to
$A$ microammeter has a resistance of $100\,\Omega$ and $a$ full scale range of $50\,\mu$ $A$. It can be used as a voltmeter or a higher range ammeter provided a resistance is added to it. Pick the correct range and resistance combination $(s)$.
Current $i$ is carried in a wire of length $L$. If the wire is turned into a circular coil, the maximum magnitude of torque in a given magnetic field $B$ will be