Origin of Magnetic Field

Q. A magnetic field can be produced by

1. A moving charge
2. A changing electric field
3. Both of these
4. None of these

Q. a magnet is brought near a coil in two ways 1. rapidly 2.slowly The induced charge will be --
A) more in case 1
B) more in case 2
C) equal in both the cases
D)more or less according to the radius of the coil

Q. The change in the magnetic dipole moment associated with the orbit, at the end of the time interval of the magnetic field change, is

1. $\gamma BQ{R}^2$
2. $-\gamma BQ{R}^2$
3. $\gamma \frac{BQ{R}^2}{2}$
4. $-\gamma \frac{BQ{R}^2}{2}$

Q. A magnetic field can be produced by

1. A moving charge
2. A changing electric field
3. None of these
4. Both moving charge & changing electric field

Q. A positive charge is moving towards a person. The direction of magnetic field lines will be in:

1. $\text{Clockwise Direction}$
2. $\text{Anticlockwise Direction}$
3. $\text{Vertically Upward direction}$
4. $\text{Vertically Downward direction}$

Q.

Magnetism was first discovered in………….

Q. Pick correct statements from among the following :
a) Electric field and magnetic field are basically independent
b) Electric field and magnetic field are to aspects of the electromagnetic field
c) Electric field and magnetic field may be produced by charge at rest
d) A moving charge produces both electric and magnetic fields

1. a and b are correct
2. b and d are correct
3. a, c and d are correct
4. b, c and d are correct

Q. An electron is revolving around a proton in a circular orbit of radius $\frac{1}{2}{A}^{\circ }$. If it produces a magnetic field of 14 T, its angular velocity in rad/s

1. $4\times {10}^{16}$
2. $4\times {10}^{17}$
3. $4\times {10}^{18}$
4. $4\times {10}^{-15}$

Q.

Show the magnetic field for an isolated electron ignoring earth's effect.

Q. Lodestone, which had magnetic properties was apparently first found where?

1. Magnesia, Greece
2. Magnetica, Italy
3. Magnemon, Turkey
4. New York, USA

Q. What is Bohr magneton?

Q. Energy in a current carrying coil is stored in the form of

1. electric field
2. magnetic field
3. dielectric strength
4. heat

Q. An electron and a proton are moving on straight parallel paths with same velocity. They enter a semi-infinite region of uniform magnetic field perpendicular to the velocity. Which of the following statement(s) $is/are$ true?

1. They will come out travelling along parallel paths.
2. They will come out at the same time.
3. They will come out at different times.
4. They will never come out of the magnetic field region.

Q. Where does the magnetic force originate?

1. Ferromagnetic materials like iron.
2. The earth's North and South Pole.
3. The centre of the Universe.
4. The motion of electrons in atoms.

Q. The magnetic moment vectors ${\mu }_s$ and ${\mu }_l$ associated with the intrinsic spin angular momentum $S$ and orbital angular momentum $l$, respectively, of an electron are predicted by quantum theory (and verified experimentally to a high accuracy) to be given by:
${\mu }_s=-\left(e/m\right)S$,
${\mu }_l=-\left(e/2m\right)l$
Which of these relations is in accordance with the result expected classically ? Outline the derivation of the classical result.

Q.

Q. A compass needle placed just above a wire in which electrons are moving toward west, will point:

1. West
2. East
3. South
4. North

Q. An electron orbiting in H atom has energy level -3.4 eV. Its angular momentum will be:

1. $2.1\times {10}^{-29}Js$
2. $4\times {10}^{-20}Js$
3. $2.1\times {10}^{-34}Js$
4. $4\times {10}^{-34}Js$

Q.

what is the difference b/w eddy current and induced current by faradays experiment

Q. An electron moving with uniform velocity in x direction enters a region of uniform magnetic field along y direction. Which of the followed physical quantity(ies) is (are) non-zero and remain constant?
I. Velocity of the electron.
II Magnitude of the momentum of the election.
III. Force on the electron.
IV. The kinetic energy of electron.

1. Only I and II
2. Only III and IV
3. All four
4. Only II and IV

Q. Assertion :If current decreases in a loop placed parallel and co-axially with other loop without current, they attract each other. Reason: Direction of induced current in the second loop is in same direction as in current carrying loop.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q. An electron moves in a circle of radius 1.0 cm with a constant speed of $4.0\times {10}^{6}m/s,$ the electric current at a point on the circle will be :
$(e=-1.6\times {10}^{-19}C)$

1. $1\times {10}^{-11}\Omega$
2. $1.1\times {10}^{-7}\Omega$
3. $2.1\times {10}^{-7}\Omega$
4. $5.1\times {10}^{-7}\Omega$

Q. An electron is revolving around a proton in a circular orbit of radius $\frac{1}{2}{A}^{\circ }$. If it produces a magnetic field of 14 T, its angular velocity in rad/s

1. $4\times {10}^{16}$
2. $4\times {10}^{-15}$
3. $4\times {10}^{17}$
4. $4\times {10}^{18}$

Q. Cathode rays enter a uniform magnetic field normal to the field. Their path is :

1. A hyperbola
2. A straight line
3. A parabola
4. A circle

Q. The radius of an $\alpha$-particle moving in a circle in a constant magnetic field is half of the radius of an electron moving in circular path in the same field. The de Broglie wavelength of $\alpha$-particle is $x$ times that of the electrons. Find $x$ (an integer).

Q. An electron and a proton of equal momentum enter a uniform magnetic field normal to the lines of force. If the radii of circular paths be $r_e$ and $r_p$, respectively, then

1. $\left(\frac{r_e}{r_p}\right)=\sqrt{\frac{m_e}{m_p}}$
2. $\left(\frac{r_e}{r_p}\right)=\sqrt{\frac{m_p}{m_e}}$
3. $\left(\frac{r_e}{r_p}\right)=\left(\frac{1}{1}\right)$
4. $\left(\frac{r_e}{r_p}\right)=\left(\frac{m_p}{m_e}\right)$

Q. A stationary electric charge on a body produces

1. a magnetic field only
2. an electric field only
3. both electric and magnetic field
4. neither electric nor magnetic field

Q. Where does the magnetic force originate?

1. Ferromagnetic materials like iron.
2. The earth's North and South Pole.
3. The centre of the Universe.
4. The motion of electrons in atoms.

Q.

Magnetism was first discovered in_________.

Q.