Advertisements
Advertisements
प्रश्न
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?
उत्तर
Given:
Deflection in the magnetometer in the given position when placed in the magnetic field of a short magnet, θ = 37°
Separation between the magnet and the needle, d = 10 cm = 0.1 m
Let M be the magnetic moment of the magnet and BH be Earth's horizontal magnetic field.
According to the magnetometer theory,
`M/B_H = (4pi)/(u_0) ((d^2 - l^2)^2)/(2d) tan θ`
For the short magnet ,
`M/B_H = (4pi)/(u_0) xx d^4/(2d) tanθ`
⇒`M/B_H = (4pi)/(4pi xx 10^-7) xx (0.1)^3/2 xx tan 37^circ`
⇒`M/B_H = 0.5 xx 0.75 xx 1 xx 10^4`
⇒`M/B_H =3.75 xx 10^3 "A-m"^2"/""T"`
= 3.75 × 103 A-m2/T
Deflection in the magnetometer θ = 37°
From the magnetometer theory in Tan-B position, we have
`M/B_H = (4pi)/(u_0)(d^2 + l^2)^(3/2)` tan θ
Since for the short magnet / << d , we can neglect l w.r.t d.
Now ,
`M/B_H = (4pi)/(u_0) d^3 tanθ`
⇒ `3.75 xx 10^3 = 1/10^-7 xx d^3 xx 0.75`
⇒ `d^3 = (3.75 xx 10^3 xx 10^-7)/(0.75) = 5 xx 10^-4`
⇒ `d = root(3) (5 xx 10^-4)`
⇒ `d = 0.076 "m" = 7.9 "cm"`
Magnet will be at 7.9 cm from the centre.
APPEARS IN
संबंधित प्रश्न
State two advantages of an electromagnet over a permanent magnet.
Write two characteristics of a material used for making permanent magnets ?
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.
The force on a north pole, `vecF = mvecB` , parallel to the field `vecB` . Does it contradict our earlier knowledge that a magnetic field can exert forces only perpendicular to itself?
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 tangent galvanometer is connected directly to an ideal battery. If the number of turns in the coil is doubled the deflection will
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 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.
Why is it not possible to make permanent magnets from paramagnetic materials?
The desirable properties for making permanent magnets are _________________ .
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.
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.
What should be retentivity and coercivity of permanent magnet?
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?
