Advertisements
Advertisements
प्रश्न
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?
Advertisements
उत्तर
Given :
Ratio , `M/B_H = 40 "Am"^2"/"T`
Since the magnet is short, l can be neglected.
So, using the formula for `M/B_H` from the magnetometer theory and substituting all values, we get
`M/B_H = (4pi)/(u_0) (d^3)/2 = 40`
⇒ `d^3 = 40 xx 10^-7 xx 2`
⇒ `d^3 = 8 xx 10^-6`
⇒ `d = 2 xx 10^-2 "m" = 2 "cm"`
Thus, the magnet should be placed in such a way that its north pole points towards the south and it is 2 cm away from the needle.
APPEARS IN
संबंधित प्रश्न
State any two advantages of electromagnets over permanent magnets.
Why should the material used for making permanent magnets have high coercivity?
Can we have a single north pole, or a single south pole?
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.
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 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 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.
If the earth's magnetic field has a magnitude 3.4 × 10−5 T at the magnetic equator of the earth, what would be its value at the earth's geomagnetic poles?
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?
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.
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 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.
Soft iron is used to make the core of the transformer because of its ______.
Answer in brief.
Explain one application of electromagnet.
Assertion: Electromagnetic are made of soft iron.
Reason: Coercivity of soft iron is small.
Which of the following is most suitable for the core of an electromagnet?
Which magnetic properties are desirable for making a permanent magnet?
