An iron bar falling vertically through the hollow region of a thick cylindrical shell made of copper experiences a retarding force and attains a terminal velocity. What can you conclude about the iron bar?

A solid ball of density rho_(1) and radius r falls vertically through a liquid of density rho_(2) . Assume that the viscous force acting on the ball is F = krv , where k is a constant and v its velocity. What is the terminal velocity of the ball ?

(A): A bar magnet is dropped into a long vertical copper tube. Even taking air resistance as negligible, the magnet attains a constant terminal velocity. If the tube is heated, the terminal velocity gets increased. (R) : The terminal velocity depends on eddy current produced in bar magnet.

An iron ball of radius 0.3 cm falls through a column of oil of density 0.94 g cm^(-3) . If it attains a terminal velocity of 0.54 m s^(-1) , what is the viscosity of oil? Density of iron is 7.8 g cm^(-3)

An iron ball of radius 0.3 cm falls through a column of oil of density 0.94 gcm ^(-3) .It is found to attain a terminal velocity of 0.5 cm s ^(-1) . Determine the viscosity of the oil. Given that the density of iron is 7.8 gcm^(-3)

Two parallel vertical metallic bars XX.and YY., of negligible resistance and separated by a length .l., are as shown in Fig. The ends of the bars are joined by resistance R_(1) and R_(2) . A uniform magnetic field of induction B exists in space normal to the plane of the bars. A horizontal metallic rod PQ of mass m starts falling vertically, making contact with the bars. It is observed that in the steady state the powers dissipated in the resistance R_(1) and R_(2) are P_(1) and P_(2) respectively. Find an expression for R_(1), R_(2) and the terminal velocity attained by the rod PQ

(a) What happens if a bar magnet is cut into two pieces (i) transverse to its length (ii) along its length? (b) What happens if an iron bar magnet is melted? Does it retain its magnetism? (c) A magnetised needle in a uniform magnetic field experiences a torque but no net force. However, an iron nail near a bar magnet experiences a force of attration in addition to a torque, explain. (d) Must every magnetic field configuration have a north pole and a south pole? What about the field due to a toroid? (e) Can you think of magnetic field configuration with three poles? (f) Two identical looking iron bars A and B are given, one of which is definitely known to be magnetised. How would one ascertain whether or not both are magnetised? If only one is magnetised how does one ascertain which one? Use nothing else but the bars A and B.

A conducting ring of circular cross - section with inner and outer radii a and b is made out of a material of resistivity rho . The thickness of the ring is h. It is placed coaxially in a vertical cylindrical region of a magnetic field B=krt. Where k is a positive constant, r is the distance from the axis and t is the time. If the current through the ring is I=((kh)/(alphap))[b^(3)-a^(3)] , then what is the value of alpha ?

A horizontally oriented uniform disc of mass M and radius R rotates freely about a stationary vertical axis passing through its centre. The disc has a radial guide along which can slide without friction a small body of mass m . A light thread running down through the hollow axle of the disc is tied to the body initially the body was located at the edge of the disc and the whole system rotated with ann angular velocity omega_(0) . Then by means of a force F applied to the lower and of the thread the body was slowly pulled to the rotation axis. find: (a). The angular velocity of the system in its final state. (b). The work performed by the force F.

A uniform bar of mass m is supported by a pivot at its top about which the bar can swing like a pendulum. If a force F is applied perpendicular to the lower end of the bar as shown in figure, what is the value of F in order to hold the bar in equilibrium at an angle (theta) from the vertical