A circular loop is kept in that vertical plane which contains the north-south direction. It carries a current that is towards south at the topmost point. Let $A$ be a point on axis of the circle to the east of it and $B$ a point on this axis to the west of it. The magnetic field due to the loop :-
Ais towards east at $A$ and towards west at $B$
Bis towards west at $A$ and towards east at $B$
Cis towards east at both $A$ and $B$
Dis towards west at both $A$ and $B$
Medium
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Cis towards east at both $A$ and $B$
c
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A galvanometer of resistance $50\, \Omega$ is connected to a battery of $3\, V$ along with a resistance of $2950\, \Omega$ in series. A full scale deflection of $30$ divisions is obtained in the galvanometer. In order to reduce this deflection to $20$ divisions, the resistance in series should be.......$Ω$
A closely packed coil having $1000$ turns has an average radius of $62.8\,cm$. If current carried by the wire of the coil is $1\,A$, the value of magnetic field produced at the centre of the coil will be (permeability of free space $=4 \pi \times 10^{-7}\,H / m$ ) nearly
A galvanometer having a coil resistance of $100\ \Omega$. gives a full scale deflection, when a currect of $I\ mA$ is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of $10\ A$, is :......$Ω$
A moving coil galvanometer allows a full scale current of $10^{-4}\, A$. A series resistance of $2\, M\,\Omega $ is required to convert the above galvanometer into a voltmeter of range $0 -5\, V$. Therefore the value of shunt resistance required to convert the above galvanometer into a ammeter of range $0-10\, mA$ is....$\Omega $
To produce a uniform magnetic field directed parallel to a diameter of a cylindrical region, one can use the saddle coils illustrated in figure. The loops are wrapped over a somewhat flattened tube. Assume the straight sections of wire are very long. The end view of the tube shows how the windings are applied. The overall current distribution is the superposition of two overlapping,circular cylinders of uniformly distributed current, one toward you and one away from you. The current density $J$ is the same for each cylinder. The position of the axis of one cylinder is described by a position vector a relative to the other cylinder. The magnetic field inside the hollow tube is.
There are three voltmeters of the same range but of resistances $10000\,\Omega $, $8000\,\Omega $ and $4000\,\Omega $ respectively. The best voltmeter among these is the one whose resistance is ................ $\Omega $
When a galvanometer is shunted with a $4\,\Omega$ resistance, the deflection is reduced to one-fifth. If the galvanometer is further shunted with $2\,\Omega$ wire, the further reduction in the deflection will be (the main current remains same)