Advertisements
Advertisements
Question
Two bar magnets are placed close to each other with their opposite poles facing each other. In absence of other forces, the magnets are pulled towards each other and their kinetic energy increases. Does it contradict our earlier knowledge that magnetic forces cannot do any work and hence cannot increase kinetic energy of a system?
Advertisements
Solution
Yes, it contradicts our earlier knowledge that magnetic forces cannot do any work and hence cannot increase the kinetic energy of the system. When opposite poles are facing each other, an attractive force acts between them so the magnets are pulled towards each other. As the two magnets come close to each other so the force between them increases and hence, the kinetic energy also increases.
APPEARS IN
RELATED QUESTIONS
Magnetic lines of force are closed continuous curves.
How are the magnetic field lines different from the electrostatic field lines?
Predict the polarity of the capacitor in the situation described below :
An electron moves along +x direction. It enters into a region of uniform magnetic field `vec B` directed along −z direction as shown in fig. Draw the shape of the trajectory followed by the electron after entering the field.
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.
Answer the following question in detail.
A circular magnet is made with its north pole at the centre, separated from the surrounding circular south pole by an air gap. Draw the magnetic field lines in the gap.
A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.25 T experiences a torque of magnitude equal to 4.5 × 10–2 J. What is the magnitude of magnetic moment of the magnet?
If the bar magnet is turned around by 180°, where will the new null points be located?
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 ______.
Which of the following statement about magnetic field lines is true?
The magnetic moment of atomic neon is equal to
At a certain 100 p of reduces 0.0/57 m carrier a current of 2 amp. The magnetic field at the centre of the coop is [`mu_0 = 4pi xx 10^-7` wb/amp – m]
A magnetic needle suspended freely orients itself:-
Magnetic dipole moment is a ______
A bar magnet of magnetic moment m and moment of inertia I (about centre, perpendicular to length) is cut into two equal pieces, perpendicular to length. Let T be the period of oscillations of the original magnet about an axis through the midpoint, perpendicular to length, in a magnetic field B. What would be the similar period T′ for each piece?
Verify the Ampere’s law for magnetic field of a point dipole of dipole moment m = m`hatk`. Take C as the closed curve running clockwise along (i) the z-axis from z = a > 0 to z = R; (ii) along the quarter circle of radius R and centre at the origin, in the first quadrant of x-z plane; (iii) along the x-axis from x = R to x = a, and (iv) along the quarter circle of radius a and centre at the origin in the first quadrant of x-z plane.
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 ______.
