Tag: properties of magnet

Quizzes (7) Questions (59)

Questions Related to properties of magnet

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

If a charged particle goes unaccelerated in a region containing electric and magnetic fields:

  1. ${\vec E}$ must be parallel to ${\vec B}$

  2. ${\vec V}$ must be perpendicular to Electric field

  3. ${\vec V}$ must be parallel to ${\vec B}$

  4. $E$ must be equal to $vB$.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

velocity must be perpendicular to B and d)E must be equal to vB. Explanation: Lorenz force is computed as F = q (E + v × B)

So, if particle is accelerated we must have qE = qvB and v × B = −vB First is possible when d is true and second is possible when d is true

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics

An AC rms voltage of 2$\mathrm { V }$ having a frequeney of 50$\mathrm { KH }$ is applied to a condenser of capacity of 10 $\mu F$ The maximum value of the magnetic field between the plates of the condenser if the radius of plate is 10$\mathrm { cm }$ is

  1. 0.4$\pi \mu T$

  2. 4$\pi \mu T$

  3. 4$\mu T$

  4. 40$\pi \mu T$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The displacement current I_d = epsilon_0 * d(Phi_E)/dt. For a capacitor, I_d = I_c = V / X_c = V / (1 / (omega * C)) = V * omega * C. The magnetic field B at radius r is given by B * 2 * pi * r = mu_0 * I_d * (r^2 / R^2). Substituting values: omega = 2 * pi * 50 * 10^3, C = 10 * 10^-6, V = 2. I_d = 2 * 2 * pi * 50 * 10^3 * 10 * 10^-5 = 2 * pi Amps. At r = R = 0.1m, B = (mu_0 * I_d) / (2 * pi * R) = (4 * pi * 10^-7 * 2 * pi) / (2 * pi * 0.1) = 4 * pi * 10^-6 T = 4 * pi microT.

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

The magnetic fields of atoms in a material are grouped together and aligned to form _________.

  1. Strong magnetic fields

  2. An area of magnetic field

  3. A region called magnetic domain

  4. A bar magnet
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A magnetic domain is a region within a magnetic material in which the magnetization is in a uniform direction. This means that the individual magnetic moments of the atoms are aligned with one another and they point in the same direction.

The magnetic fields of atoms in a material are grouped together and aligned to form  region called magnetic domain

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

The smallest magnet available is ___________.

  1. a bar magnet with an area of $1 mm^2$

  2. a spinning electron

  3. a magnetic dipole

  4. a molecule or atom with a magnetic dipole
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An electron is not a spinning ball of charge and the intrinsic spin of particles cannot be understood in such terms. a value of the ratio between the magnetic moment and the angular momentum that is a factor 2 too small.

The smallest magnet available is a spining electron.

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

The magnetic domains of an unmagnetised object are found ___________.

  1. Parallel to each other

  2. Perpendicular to each other

  3. Pointing towards south

  4. Pointing in different direction
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A magnetic domain is the region in which the magnetic fields of atoms are grouped together and aligned. In an unmagnetized object the magnetic domains are pointing at different directions.

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

The primary origin of magnetism lies in the

  1. atomic current and intrinsic spin of electrons.

  2. polar and non polar nature of molecules.

  3. pauli exclusion principle.

  4. electronegative nature of materials
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Atomic currents and intrinsic spins of electrons are responsible for origin of magnetism.

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

If we go inside a mine and drop a $104 lb$  iron ball and $1$ lb aluminum ball from the top of a high platform, neglecting air resistance.

  1. Both will reach the floor at the same time

  2. $1$ lb weight will reach the floor first

  3. $10$ lb weight will reach the floor first

  4. It is not possible to indicate which of the two will reach the floor first without further data
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In real life the one having less volume and more weight will reach first

but in ideal situation where viscosity of air is neglected both will hit ground at same time irrespective of their masses if dropped from the same height 

this is because the acceleration produced due to gravity does not depend on the body.


Multiple choice magnetic compass magnetic poles and magnetic compass properties of magnet effect of electric current physics

The marked end of a compass needle always points directly to

  1. Earth's geographic South Pole

  2. Earth's geographic North Pole

  3. A magnet's south pole

  4. A magnet's north pole
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The marked end of compass needle always points to the south pole of a magnet.

The geographic north pole of the earth is the magnetic south pole. 
Hence it points towards the geographic north pole of earth.

Multiple choice magnetic compass magnetic poles and magnetic compass properties of magnet effect of electric current physics

The tangent law is applicable only when

  1. There are atleast two magnetic field

  2. There are two uniform magnetic fields mutually perpendicular to each other

  3. One strong magnetic field and the other weak magnetic field

  4. In the present magnetic fields one should be horizontal component of the earth's magnetic field
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The tangent law states that if a magnetic needle is placed in two mutually perpendicular uniform magnetic fields B and H, it will come to rest at an angle theta such that B = H tan(theta).

Multiple choice magnetic compass magnetic poles and magnetic compass properties of magnet effect of electric current physics

A compass needle which is allowed to move in horizontal plane is taken to a geomagnetic pole. It

  1. will stay in north-south direction only

  2. will stay in east -west direction only

  3. will become rigid showing no movement

  4. will stay in any position
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

At pole's horizontal component of earth's magnetic field is zero therefore, if needle is hold horizontally then it will stay in any position.