Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
Given :
Frequency of oscillations of the bar magnet in the oscillation magnetometer, `V = 40 "min"^-1`
Time period for which the bar magnet is placed in the oscillation magnetometer, T1 = `1/40 min`
The time period of oscillations of the bar magnet (T) is given by `T = 2pi sqrt(I/(MB_H)`
Here,
I = Moment of inertia
M = Magnetic moment of the bar magnet
BH = Horizontal component of the magnetic field
Now, let T2 be the time period for which the second demagnetised magnet is placed over the magnet.
As the second magnet is demagnetised, the combination will have the same values of Mand BH as those for the single magnet. However, variation will be there in the value of Ion placing the second demagnetised magnet.
`therefore` `T_1/T_2 = I_1/I_2`
⇒ `1/(40T_2) = sqrt(1/2)`
⇒ `1/(1600 T_2^2) = 1/2`
⇒ `T_2^2 = 1/800`
⇒ `T_2 = 0.03536 min`
For 1 oscillation,
Time taken = 0.03536 min
For 40 oscillations,
Time taken = 0.03536 × 40
= `1.414 min = sqrt(2) min`
APPEARS IN
संबंधित प्रश्न
What are permanent magnets? Give one example ?
A tangent galvanometer is connected directly to an ideal battery. If the number of turns in the coil is doubled the deflection will
If the current is doubled, the deflection is also doubled in
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.
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.
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.
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.
The desirable properties for making permanent magnets are _________________ .
The coercive force for a certain permanent magnet is 4.0 × 104 A m−1. This magnet is placed inside a long solenoid of 40 turns/cm and a current is passed in the solenoid to demagnetise it completely. Find the current.
The needle of a dip circle shows an apparent dip of 45° in a particular position and 53° when the circle is rotated through 90°. Find the true dip.
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.
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 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 ______.
Which property of soft iron makes it useful for preparing electromagnet?
Assertion: Electromagnetic are made of soft iron.
Reason: Coercivity of soft iron is small.
The relation b/w magnetic susceptibility xm and relativ~ permeability µr is
A wire of length 2 m carrier of lamp is bend to form a circle. The magnetic moment of a coil is :-
