Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
Given :
Number of turns in the coil, n = 50
Area of the cross section of the coil, A = 2 cm × 2 cm = 2 × 2 × 10−4 m2
Current flowing through the coil, `I = 20 × 10^−3 A`
Magnetic field strength due to the presence of the poles, B = 0.5 T
The torque experienced by the coil placed in an external magnetic field `(tau)` is given by
`τ = nI (vec A xx vec B)`
⇒ `τ = nIAB sin 90^circ`
⇒ `τ = 50 xx 20 xx 10^-3 xx 4 xx 10^-4 xx 0.5`
⇒ `τ = 2 xx 10^-4 "N - m"`
APPEARS IN
संबंधित प्रश्न
State two advantages of an electromagnet over a permanent magnet.
What are permanent magnets? Give one example ?
Magnetic meridian is
Consider the situation of the previous problem. The directions of the magnetic field due to the dipole are opposite at
(a) P1 and P2
(b) Q1 and Q2
(c) P1 and Q1
(d) P2 and Q2
Do permeability and relative permeability have the same dimensions?
Why is it not possible to make permanent magnets from paramagnetic materials?
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 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.
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 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.
In a permanent magnet at room temperature ______.
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 :-
