Advertisements
Advertisements
प्रश्न
Which property of soft iron makes it useful for preparing electromagnet?
Advertisements
उत्तर
When a current is passed through an electromagnet's coil, it should become magnetic, but once the current is turned off, it should lose its magnetism. As a result, the ferromagnetic core (usually iron-based) used in an electromagnet should have high permeability and low retentivity, i.e. be magnetically'soft.'
APPEARS IN
संबंधित प्रश्न
What are permanent magnets? Give one example ?
Why is the core of an electromagnet made of ferromagnetic materials?
Magnetic scalar potential is defined as `U(vec r_2) - U(vec r_1) = - ∫_vec(r_1)^vec(r_2)` `vec (B) . dvec(l)`
Apply this equation to a closed curve enclosing a long straight wire. The RHS of the above equation is then `-u_0 i` by Ampere's law. We see that `U(vec(r_2)) ≠ U(vec(r_1))` even when `vec r_2 =vec r_1` .Can we have a magnetic scalar potential in this case?
A dip circle is taken to geomagnetic equator. The needle is allowed to move in a vertical plane perpendicular to the magnetic meridian. The needle will stay ______.
If the current is doubled, the deflection is also doubled in
A very long bar magnet is placed with its north pole coinciding with the centre of a circular loop carrying as electric current i. The magnetic field due to the magnet at a point on the periphery of the wire is B. The radius of the loop is a. The force on the wire is
Consider the situation of the previous problem. The directions of the magnetic field due to the dipole are opposite at
(a) P1 and P2
(b) Q1 and Q2
(c) P1 and Q1
(d) P2 and Q2
To measure the magnetic moment of a bar magnet, one may use
(a) a tangent galvanometer
(b) a deflection galvanometer if the earth's horizontal field is known
(c) an oscillation magnetometer if the earth's horizontal field is known
(d) both deflection and oscillation magnetometer if the earth's horizontal field is not known
Two long bare magnets are placed with their axes coinciding in such a way that the north pole of the first magnet is 2.0 cm from the south pole of the second. If both the magnets have a pole strength of 10 Am, find the force exerted by one magnet of the other.
Figure shows some of the equipotential surfaces of the magnetic scalar potential. Find the magnetic field B at a point in the region.
A magnetic dipole of magnetic moment `1.44 "A m"^2`is placed horizontally with the north pole pointing towards north. Find the position of the neutral point if the horizontal component of the earth's magnetic field is 18 μT.
Do permeability and relative permeability have the same dimensions?
Why is it not possible to make permanent magnets from paramagnetic materials?
The magnetic field due to the earth has a horizontal component of 26 μT at a place where the dip is 60°. Find the vertical component and the magnitude of the field.
A short magnet produces a deflection of 37° in a deflection magnetometer in Tan-A position when placed at a separation of 10 cm from the needle. Find the ratio of the magnetic moment of the magnet to the earth's horizontal magnetic field.
A deflection magnetometer is placed with its arms in north-south direction. How and where should a short magnet having M/BH = 40 A m2 T−1 be placed so that the needle can stay in any position?
The combination of two bar magnets makes 10 oscillations per second in an oscillation magnetometer when like poles are tied together and 2 oscillations per second when unlike poles are tied together. Find the ratio of the magnetic moments of the magnets. Neglect any induced magnetism.
A bar magnet makes 40 oscillations per minute in an oscillation magnetometer. An identical magnet is demagnetized completely and is placed over the magnet in the magnetometer. Find the time taken for 40 oscillations by this combination. Neglect any induced magnetism.
Answer in brief.
Explain one application of electromagnet.
Assertion: Electromagnetic are made of soft iron.
Reason: Coercivity of soft iron is small.
A wire of length 2 m carrier of lamp is bend to form a circle. The magnetic moment of a coil is :-
A steel wire of length 1 has a magnetic moment m it is then bent into a semicircular arc. The new magnetic moment is
Which of the following is most suitable for the core of an electromagnet?
Which magnetic properties are desirable for making a permanent magnet?
