Advertisements
Advertisements
प्रश्न
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
Advertisements
उत्तर
(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 magnetometers if the earth's horizontal field is not known
Denial of (a):
Tangent galvanometer is an instrument used to measure electric current; it cannot be used to the measure magnetic moment of a bar magnet.
Justification of (b) and (c) :
Deflection magnetometer is used to measure `M/B_H` of a permanent bar magnet.
Similarly, oscillation magnetometer is used to measure `MB_H` of a bar magnet. So, if earth's horizontal field, `B_H` is known, then the magnetic moment of a bar magnet, M, can be measured.
Justification of (d):
Using deflection and oscillation magnetometers, we can calculate `M/B_H` and `MB_H` respectively . Therefore, if we multiply the result obtained from both the instruments, then BH cancels out as `M/B_H xx MB_H = M^2` . Thus, the value of `B_H` is not required.
Therefore, we can use both deflection and oscillation magnetometers if the earth's horizontal field is not known.
APPEARS IN
संबंधित प्रश्न
Can we have a single north pole, or a single south pole?
Which of the following four graphs may best represent the current-deflection relation in a tangent galvanometer?
A uniform magnetic field of `0.20 xx 10^-3 "T"` exists in the space. Find the change in the magnetic scalar potential as one moves through 50 cm along the field.
Show that the magnetic field at a point due to a magnetic dipole is perpendicular to the magnetic axis if the line joining the point with the centre of the dipole makes an angle of `tan^-1(sqrt 2)` with the magnetic axis
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.
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 magnetic needle is free to rotate in a vertical plane which makes an angle of 60° with the magnetic meridian. If the needle stays in a direction making an angle of `tan^-1(2sqrt(3))` with the horizontal, what would be the dip at that place?
A moving-coil galvanometer has a 50-turn coil of size 2 cm × 2 cm. It is suspended between the magnetic poles producing a magnetic field of 0.5 T. Find the torque on the coil due to the magnetic field when a current of 20 mA passes through it.
The magnetometer of the previous problem is used with the same magnet in Tan-B position. Where should the magnet be placed to produce a 37° deflection of the needle?
A bar magnet takes π/10 second the complete one oscillation in an oscillation magnetometer. The moment of inertia of the magnet about the axis of rotation is 1.2 × 10−4 kg m2 and the earth's horizontal magnetic field is 30 μT. Find the magnetic moment of the magnet.
A short magnet oscillates in an oscillation magnetometer with a time period of 0.10 s where the earth's horizontal magnetic field is 24 μT. A downward current of 18 A is established in a vertical wire placed 20 cm east of the magnet. Find the new time period.
A short magnet makes 40 oscillations per minute when used in an oscillation magnetometer at a place where the earth's horizontal magnetic field is 25 μT. Another short magnet of magnetic moment 1.6 A m2 is placed 20 cm east of the oscillating magnet. Find the new frequency of oscillation if the magnet has its north pole (a) towards north and (b) towards south.
Soft iron is used to make the core of the transformer because of its ______.
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 :-
