Question 1 :
A long solenoid is formed by the winding $20\ turns/cm$. What will be the current necessary to produce a magnetic field of $20\ millitesla$ inside the solenoid?<br>($\dfrac { { \mu }_{ 0 } }{ 4\pi } ={ 10 }^{ -7 }tesla\quad -meter/ampere$)<br>

Question 2 :
Two beams of protons moving parallel in same direction will :

Question 3 :
The restoring couple in the moving coil galvanometer is due to<br/>

Question 5 :
The gyro-magnetic ratio of an electron in an H-atom, according to Bohr's model, is

Question 6 :
In cyclotron, for a given magnet, radius of the semicircle traced by positive ion is directly proportional to__________. (v=velocity of positron ion)<br/>

Question 7 :
Two parallel wires carrying current in the same direction attract each other because of<br>

Question 8 :
For an ideal toroid, in which turns are closely spaced, the external magnetic field is

Question 9 :
A charged particle with charge $q$enters a regionof constant uniform and mutually orthogonal fields$\vec{E}$ and $\vec{B}$with a velocity $\vec{v}$ perpendicular to both$\vec{E}$ and $\vec{B}$ and comes out without any change in magnitude and direction of $\vec{v}$. Then,<br>

Question 10 :
In a moving coil galvanometer, the deflection of the coil $\theta$ is related to the electric current $i$ by the relation<br>

Question 11 :
The force of repulsion between two parallel wires is $f$ when each one of them carries a certain current I. If the current in each is doubled, the force between them would be

Question 12 :
A wire of length $L$ is made in the form of a coil in a moving coil galvanometer. To have maximum sensitiveness the shape of the coil is&#160;<br/>

Question 16 :
&#160;A device used for measuring small currents due to changing magnetic field is known as:

Question 17 :
The coil of the moving coil galvanometer is wound over an aluminium frame<br/>

Question 18 :
In which &#160;form &#160;the field lines inside the infinite solenoid are present ?<br/>

Question 19 :
The magnetic field lines inside the solenoid are in the form of

Question 20 :
An 8 cm long wire carrying a current of 10 A is placed inside a solenoid perpendicular to its axis. If the magnetic field inside the solenoid is 0.3 T, then magnetic force on the wire is

Question 21 :
Two identical current carrying coaxial loops, carry current I in opposite sense. A simple amperian loop passes through both of them once. Calling the loop as C, then which statement is correct?<br>

Question 22 :
The percentage increase in magnetic field B when the space within a current carrying toroid is filled with aluminium ($\chi =2.1\times 10{-5}$) is?

Question 23 :
A solenoid of length $l$ and having $n$ turns carries a current $i$ in anticlockwise direction. The magnetic field produced by it is :<br/>

Question 24 :
A current passing through a circle coil of two turns produces a magnetic field $B$as its centre. The coil is then rewound so as to have four turns and the same current is passed through it. The magnetic field at its centre now is

Question 25 :
A tangent galvanometer has a coil with $50$ turns and radius equal to $4$ cm. A current of $0.1$ Amp is passing through it. The plane of the coil is set parallel to the earth's magnetic meridian. If the value of the earth's horizontal component of the magnetic field is $7\times 10^{-5}T$ and $\mu_0= 4\pi \times 10^{-7}Wb/A-m$. then the deflection in the galvanometer needle will be :