MCQ
A circular coil ‘$A$’ has a radius $R$ and the current flowing through it is $I$. Another circular coil ‘$B$’ has a radius $2R$ and if $2I$ is the current flowing through it, then the magnetic fields at the centre of the circular coil are in the ratio of (i.e.${B_A}$ to ${B_B}$)
  • A
    $4:1$
  • B
    $2:1$
  • C
    $3:1$
  • $1:1$

Answer

Correct option: D.
$1:1$
d
(d) $B \propto \frac{i}{r}$

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

$Assertion :$ The pressure of water reduces when it flows from a narrow pipe to a wider pipe.
$Reason :$ Since for wider pipe area is large, so flow of speed is small and pressure also reduces proportionately.
A laser beam can be focussed on an area equal to the square of its wavelength A $He-Ne$  laser radiates energy at the rate of $1\,mW$ and its wavelength is $632.8 \,nm$. The intensity of focussed beam will be
Two long straight wires are placed along $x$-axis and $y$-axis. They carry current $I_1$ and $I_2$ respectively. The equation of locus of zero magnetic induction in the magnetic field produced by them is
Three right angled prisms of refractive indices ${n_1},{n_2}$ and ${n_3}$ are fixed together using an optical glue as shown in figure. If a ray passes through the prisms without suffering any deviation, then
A photon collides with a stationary hydrogen atom in ground state inelastically. Energy of the colliding photon is $10.2 \ eV$. After a time interval of the order of micro second another photon collides with same hydrogen atom inelastically with an energy of $15 \ eV$. What will be observed by the detector
Two equal charges of magnitude $Q$ each are placed at a distance $d$ apart. Their electrostatic energy is $E$. A third charge $-Q / 2$ is brought midway between these two charges. The electrostatic energy of the system is now
The box of a pin hole camera, of length $L$, has a hole of radius $a$. It is assumed that when the hole is illuminated by a parallel beam of light of wavelength $\lambda$, the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size ( say $b_{min}$) when
If all objects on the equator of earth feel weightless then the duration of the day will nearly become ....... $hr$
When a parallel plates capacitor is connected to a source of constant potential difference,
Figure shows a cubical room $ABCD$ with the wall $CD$ as a plane mirror. Each side of the room is $3\,m$. We place a camera at the midpoint of the wall $AB$. At what distance should the camera be focussed to photograph an object placed at $A$