MCQ
The magnetic induction at a point $P$ which is distant $4\, cm$ from a long current carrying wire is ${10^{ - 8}}\,Tesla$. The field of induction at a distance $12\, cm $ from the same current would be
  • $3.33 \times {10^{ - 9}}\,Tesla$
  • B
    $1.11 \times {10^{ - 4}}\,Tesla$
  • C
    $3 \times {10^{ - 3}}\,Tesla$
  • D
    $9 \times {10^{ - 2}}\,Tesla$

Answer

Correct option: A.
$3.33 \times {10^{ - 9}}\,Tesla$
a
(a) $B = \frac{{{\mu _0}}}{{4\pi }} \cdot \frac{{2i}}{r}$

$==>$ $\frac{{{B_1}}}{{{B_2}}} = \frac{{{r_2}}}{{{r_1}}}$

$==>$ $\frac{{{{10}^{ - 8}}}}{{{B_2}}} = \frac{{12}}{4}$
$==>$ ${B_2} = 3.33 \times {10^{ - 9}}\,Tesla$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

A cell is connected between the points $A$ and $C$ of a circular conductor $ABCD$ of centre $O$ with angle $AOC = {60^o}$. If ${B_1}$ and ${B_2}$ are the magnitudes of the magnetic fields at $O$ due to the currents in $ABC$ and $ADC$ respectively, the ratio $\frac{{{B_1}}}{{{B_2}}}$ is
A sphere of mass $M$ and radius $R_2$ has a concentric cavity of radius $R_1$ as shown in figure. The force $F$ exerted by the sphere on a particle of mass $m$ located at a distance r from the centre of sphere varies as $(0 \le r \le \,\infty )$
Power on $a$ mass is $P = (3t^2 -2t + 1)$ watt change in kinetic energy in $t = 2sec$ to $t = 4sec$ is :- .................... $\mathrm{J}$
If the distance between a point source and screen is doubled, then intensity of light on the screen will become
Three rods of the same dimension have thermal conductivities $3K$ , $2K$ and $K$ . They are arranged as shown in fig. Given below, with their ends at $100^oC, 50^oC $and $20^oC$. The temperature of their junction is ......... $^oC$
A body falls freely from rest. It covers as much distance in the last second of its motion as covered in the first three seconds. The body has fallen for a time of........$s$
An $AC$ circuit has $R =100 \Omega, C =2\, \mu F$ and $L =80\, mH ,$ connected in series. The quality factor of the circuit is$.......$
A particle executes simple harmonic motion (amplitude $= A$) between $x = - A$ and $x = + A$. The time taken for it to go from $0$ to $A/2$ is ${T_1}$ and to go from $A/2$ to $A$ is ${T_2}$. Then
The total energy of an electron in the $n^{t h}$ stationary orbit of the hydrogen atom can be obtained by
Why the current does not rise immediately in a circuit containing inductance