Advertisements
Advertisements
प्रश्न
A bar magnet has a length of 8 cm. The magnetic field at a point at a distance 3 cm from the centre in the broadside-on position is found to be `4 xx 10^-6 "T"`.Find the pole strength of the magnet.
Advertisements
उत्तर
Given:
Length of the magnet, 2l = 8 cm = `8 xx 10^-2 "m"`
Distance of the observation point from the centre of the dipole, d = 3 cm
Magnetic field in the broadside-on position, B = `4 xx 10^-6 "T"`
The magnetic field due to the dipole on the equatorial point (B) is given by
`B = (u_0m2l)/(4pi(d^2 + l^2)^(3/2)`
Here, m is the pole strength of the magnet.
On substituting the respective values, we get
`4 xx 10^-6 = (10^-7"m" xx 8 xx 10^-2)/(9 xx 10^-4 + 16 xx 10^-4)^(3/2)`
⇒ `4 xx 10^-6 = ("m" xx 8 xx 10^-9)/((25)^(3/2) xx (10^-4)^(3/2)`
⇒ `"m" = (4 xx 10^-6 xx 125 xx 10^-6)/(8 xx 10^-9)`
⇒ `"m" = 6.25 xx 10^-2 "A-m"`
APPEARS IN
संबंधित प्रश्न
What are permanent magnets? Give one example ?
Why should the material used for making permanent magnets have high coercivity?
Compare the direction of the magnetic field inside a solenoid with that of the field there if the solenoid is replaced by its equivalent combination of north pole and south pole.
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 ______.
A tangent galvanometer is connected directly to an ideal battery. If the number of turns in the coil is doubled the deflection will
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.
The magnetic moment of the assumed dipole at the earth's centre is 8.0 × 1022 A m2. Calculate the magnetic field B at the geomagnetic poles of the earth. Radius of the earth is 6400 km.
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 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?
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 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.
Which property of soft iron makes it useful for preparing electromagnet?
Answer in brief.
Explain one application of electromagnet.
A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from ______.
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 :-
