Advertisements
Advertisements
Question
Answer the following question in brief.
What happens if a bar magnet is cut into two pieces transverse to its length/along its length?
Advertisements
Solution
- When a magnet is cut into two pieces, then each piece behaves like an independent magnet.
- When a bar magnet is cut transverse to its length, the two pieces generated will behave as independent magnets of reduced magnetic length. However, the pole strength of all the four poles formed will be the same as that of the original bar magnet. Thus, the new dipole moment of the smaller magnets will be,
`therefore m = m xx 2l`
`vec("m"_1)="q"_"m"(vec("l"_1))`, `vec("m"_2)="q"_"m"(vec("l"_2))`
- When the bar magnet is cut along its length, the two pieces generated will behave like an independent magnet with reduced pole strength. However, the magnetic length of both the new magnets will be the same as that of the original bar magnet. Thus, the new dipole moment of the smaller magnets will be
`vec("m"_1)=("q"_"m")_1(2vec("l"))`, `vec("m"_2)=("q"_"m")_2(2vec("l"))`
Pole strength is directly proportional to cross-section area.
APPEARS IN
RELATED QUESTIONS
Write any three properties of magnetic lines of force.
Predict the polarity of the capacitor in the situation described below :
A bar magnet of length 1 cm and cross-sectional area 1.0 cm2 produces a magnetic field of 1.5 × 10−4 T at a point in end-on position at a distance 15 cm away from the centre. (a) Find the magnetic moment M of the magnet. (b) Find the magnetisation I of the magnet. (c) Find the magnetic field B at the centre of the magnet.
Answer the following question.
Write the four important properties of the magnetic field lines due to a bar magnet.
Choose the correct option.
Inside a bar magnet, the magnetic field lines
Solve the following problem.
A magnetic pole of a bar magnet with a pole strength of 100 A m is 20 cm away from the centre of a bar magnet. The bar magnet has a pole strength of 200 A m and has a length of 5 cm. If the magnetic pole is on the axis of the bar magnet, find the force on the magnetic pole.
Solve the following problem.
Two small and similar bar magnets have a magnetic dipole moment of 1.0 Am2 each. They are kept in a plane in such a way that their axes are perpendicular to each other. A line drawn through the axis of one magnet passes through the center of other magnet. If the distance between their centers is 2 m, find the magnitude of the magnetic field at the midpoint of the line joining their centers.
A closely wound solenoid of 800 turns and area of cross-section 2.5 × 10–4 m2 carries a current of 3.0 A. Explain the sense in which the solenoid acts like a bar magnet. What is its associated magnetic moment?
A closely wound solenoid of 2000 turns and area of cross-section 1.6 × 10-4 m2 , carrying a current of 4.0 A, is suspended through its centre allowing it to turn in a horizontal plane.
What is the force and torque on the solenoid if a uniform horizontal magnetic field of 7.5 × 10-2 T is set up at an angle of 30° with the axis of the solenoid?
When iron filings are sprinkled on a sheet of glass placed over a short bar magnet then, the iron filings form a pattern suggesting that the magnet has ______.
In which case of comparing solenoid and bar magnet there is no exact similarity?
According to the dipole analogy 1/ε0 corresponds to ______.
Magnetic moment for solenoid and corresponding bar magnet is ______.
A particle having charge 100 times that of an electron is revolving in a circular path by radius 0.8 with one rotation per second. The magnetic field produced at the centre is
A bar magnet of magnetic moment 3.0 Am is placed in a uniform magnetic field of 2 × 10-5T. If each pole of the magnet experience a force of 6 × 10-4 N, the length of the magnet is ______.
A toroid of n turns, mean radius R and cross-sectional radius a carries current I. It is placed on a horizontal table taken as x-y plane. Its magnetic moment m ______.
A proton has spin and magnetic moment just like an electron. Why then its effect is neglected in magnetism of materials?
Suppose we want to verify the analogy between electrostatic and magnetostatic by an explicit experiment. Consider the motion of (i) electric dipole p in an electrostatic field E and (ii) magnetic dipole m in a magnetic field B. Write down a set of conditions on E, B, p, m so that the two motions are verified to be identical. (Assume identical initial conditions.)
There are two current carrying planar coils made each from identical wires of length L. C1 is circular (radius R) and C2 is square (side a). They are so constructed that they have same frequency of oscillation when they are placed in the same uniform B and carry the same current. Find a in terms of R.
A long straight wire of circular cross section of radius 'a' carries a steady current I. The current is uniformly distributed across its cross section. The ratio of magnitudes of the magnetic field at a point `a/2` above the surface of wire to that of a point `a/2` below its surface is ______.
A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a current of 5.2 A. The coercivity of the bar magnet is ______.
In a uniform magnetic field of 0.049 T, a magnetic needle performs 20 complete oscillations in 5 seconds as shown. The moment of inertia of the needle is 9.8 × 10−6 kg m2. If the magnitude of magnetic moment of the needle is x × 10−5 Am2; then the value of ‘x’ is:
