Ampere's Circuital Law

Q.

What is the S.I. unit of magnetic flux?

Q. the electric field components in figure below are Ex=800x^{2^{}} N/c E_y=Ez=0 calculate a) the flux througu cube b) the charge within the cube

Q. A moving coil galvanometer $\text{A}$ has $100$ turns and resistance $50\Omega$. Another moving coil galvanometer $\text{B}$ has number of turns $500$ and resistance $200\Omega$. The other quantities are same in both cases. They are connected by a battery of internal resistance of $50\Omega$ respectively. The ratio of deflection of $\text{B}$ to $\text{A}$ is (Give integer value)

Q.

State and explain amperes circuital law

Q.

What is the inconsistency of Amperes Law?

Q. Which of the following graphs represent the variation of magnetic field $\left(B\right)$ with distance $\left(R\right)$ from an infinitely long straight conductor?

1. 
2. 
3. 
4. 

Q.

State amperes law?

Q. A bar magnet is released from rest along the axis of a very long, vertical copper tube. After some time the magnet

1. will stop in the tube.
2. will move with almost constant speed.
3. will move with an acceleration $g$
4. will oscillate.

Q. The number of electric field lines crossing an area $A$ is $n_1$ when $\overrightarrow{A}||\overrightarrow{E}$, while number of field lines crossing same area is $n_2$ when $\overrightarrow{E}$ makes an angle of ${30}^{\circ }$ with $\overrightarrow{A}$, then

1. $n_1=n_2$
2. $n_1>n_2$
3. $n_1<n_2$
4. $n_1\le n_2$

Q. A cylindrical cavity of diameter $a$ exists inside a cylinder of diameter $2a$ as shown in the figure. Both the cylinder and the cavity are infinitely long. A uniform current density $J$ flows along the length. If the magnitude of the magnetic field at the point $P$ is given by $\frac{N}{12}{\mu }_{0}aJ$, then the value of $N$ is

Q. Find the value of $\oint \overrightarrow{B}\cdot \overrightarrow{dl}$ for the loop $L_2$ as shown in figure. The direction of magnetic field is represented as loops and direction of current element is given in the figure.

1. ${\mu }_0(I_1-I_2)$
2. Zero
3. ${\mu }_0(I_1+I_3+I_4)$
4. ${\mu }_0(I_1-I_2+I_4)$

Q.

Ampere’s circuital law is analogous to a law in electrostatics.That law is

1. Faraday’s law

2. Kirchhoff’s law

3. Gauss’s law

4. Coulomb’s law

Q. A galvanometer has a resistance of $20\Omega$ and reads full-scale when $0.2\text{V}$ is applied across it. To convert it into a $10\text{A}$ ammeter, the galvanometer coil should have a

1. $0.01\Omega$ resistor connected across it in parallel.
2. $0.02\Omega$ resistor connected across it in parallel.
3. $200\Omega$ resistor connected in series with it
4. $2000\Omega$ resistor connected in series with it

Q.

What is Tesla in physics?

Q. A photon of energy $E$ ejects a photoelectron from a metal surface whose work function is $W_0$. If this electron enters into a uniform magnetic field of induction $B$ in a direction perpendicular to the field and describes a circular path of radius $r$, then the radius $r$ is given by: (in the usual notation)

1. $\frac{3m(E-W_0)}{eB}$
2. $\sqrt{2m(E-W_0)eB}$
3. $\frac{\sqrt{2e(E-W_0)}}{mB}$
4. $\frac{\sqrt{2m(E-W_0)}}{eB}$

Q.

Is EMF Scalar Or Vector?

Q. The magnetic field at center, $P$ will be

1. $\frac{{\mu }_0}{4\pi }$
2. $\frac{{\mu }_0}{\pi }$
3. $\frac{{\mu }_0}{2\pi }$
4. $4{\mu }_0\pi$

Q. Find the magnetic field of induction at an axial and equatorial point of a circular coil

Q. How cathode rays are deflected in magnetic field?

Q. Most important derivation for CBSE class 12 exam 2018

Q.

In a fluorescent lamp choke (a small transformer)$100\mathrm{V}$ of reversible voltage is produced when choking changes current in from $0.25\mathrm{A}\mathrm{to}0\mathrm{A}$ in $0.025\mathrm{ms}.$ The self-inductance of choke (in mH) is estimated to be?

Q. The deflection in a galvanometer falls from $50$ divisions to $20$ divisions, when a $12\Omega$ shunt (resistance connected in parallel to galvanometer) is applied. The galvanometer resistance is

1. $18\Omega$
2. $24\Omega$
3. $30\Omega$
4. $36\Omega$

Q. A particle of specific charge $0.5\text{C/kg}$ is projected in a transverse magnetic field with velocity making angle $\theta =\frac{\pi }{3}$ at $t=0$ as shown in figure.


The time spent by the particle in the magnetic field is:

1. $\frac{\pi }{3}\text{sec}$
2. $\frac{2\pi }{3}\text{sec}$
3. $\frac{\pi }{12}\text{sec}$
4. $\frac{\pi }{4}\text{sec}$

Q. Two bar magnets of same length and breadth having magnetic moments $M$ and $4M$ respectively are joined with likes poles together and suspended in a uniform magnetic field $B$, it oscillates with time period $T=\sqrt{3}\text{s}$. If the polarity of one of the magnet is reversed and the combination is again made to oscillate in the same field. Find the new time period of this combination.

1. $\sqrt{3}\text{s}$
2. $\sqrt{5}\text{s}$
3. $\sqrt{2}\text{s}$
4. $2\text{s}$

Q. An electron can remain in excited state for about ${10}^{-8}$ seconds. If in a Hydrogen atom an electron is in first excited state then select the correct statement(s).

1. Radius of circular path in 1st excited state is 212 pm
2. Speed of electron in 1st excited state is $1.1\times {10}^{6}m/s$
3. Before transition to ground state electron will make around $8.2\times {10}^6$ revolutions
4. Speed of electron decreases as it moves to ground state from excited state

Q. The magnetic field at the centre of a uniform charged ring (Q) of radius $R$ rotating at angular velocity $\omega$ about an axis passing through a diameter is $\frac{{\mu }_0}{4\pi }\frac{nQ\omega }{R}$, then n is

Q. A proton moves at a speed of $v=2\times {10}^6\text{m/s}$ in a region of constant magnetic field of magnitude $0.05\text{T}$. The direction of the proton with the field is $\theta ={30}^{\circ }$ when it enters. When you look along the direction of the magnetic field, the path is a circle projected on a plane perpendicular to the magnetic field. How far will the proton moves along the direction of $B$, when two projected circles have bean completed ?

1. $4.35\text{m}$
2. $0.209\text{m}$
3. $2.81\text{m}$
4. $2.41\text{m}$

Q. Can a gravitational field be added vectorially to an electric field to get a total field? Explain

Q. Gauss law in magnetism, $\oint \overrightarrow{B}.d\overrightarrow{A}=0$, tells us

1. that magnetic mono pole exist.
2. that magnetic mono pole does not exist.
3. Net magnetic flux through any closed surface is not zero.
4. The number of magnetic field lines entering the closed surface is not equal to the number of magnetic field lines leaving the closed surface.

Q. Two thin long parallel wires separated by a distance b are carrying a current i amp each. The magnitude of the force per unit length exerted by one wire on the other is

1. 
2. 
3. 
4.