Magnetism

Problem 145: The force acting on a pole of 3 Wb is 12 N. The magnetic intensity of the magnetic field is

Problem 146: Two straight parallel wires 2 m long and 3 mm apart carries a current of 8.0 A in opposite direction. Calculate the force between these conductors.

Problem 147: A wire 12 cm long and carrying a current of 30 A is placed in between the pole face of a magnet whose magnetic flux density is 0.9 tesla. If the wire is inclined at an angle 60 degrees from the plane of the magnetic field, what is the force exerted on the wire?

Problem 148: The reluctance of a non-magnetic circuit is 12 units. How much flux will be set up if surrounded by a coil 600 turns carrying a current of 3 A?

Problem 149: The coil in a magnetic contactor requires 0.5 A to provide a magnetizing force of 500 AT. How many turns are necessary?

Problem 150: A solenoid 30-cm long is wound with 300 turns, what is the value of its field strength inside the solenoid, when the coil is carrying a current of 2 amperes?

Problem 151: Calculate the magnetic field intensity to produce a flux density of \(10\times10^{-3}\) tesla at the center of a long straight solenoid.

Problem 152: If a current of 5 A flows through a long wire of radius 0.004 meter, what is the flux density (H) produced 0.02 meter away from the surface of the wire.

Problem 153: The relative permeability of a certain silicon steel is 4500. A certain magnetic loop consists of a silicon steel of 10 cm square, 20 cm long and an air gap of 1/4 cm. What is the reluctance of the magnetic circuit?

Problem 154: A certain laminated steel core has a permeability of 3000. The length is 5 cm and the cross section is 2 sq. cm. What is its reluctance?

Problem 155: A coil with 900 turns is wound over a magnetic core with a reluctance of 10,000 AT/Wb. If a current of 0.5 A is pass through the coil, how much is the magnetic flux that the coil generates?

Problem 156: An air-core circular coil has 5000 turns. The inner and outer diameters are 20 and 24 cm respectively. If a current of 2 A is passed through the coil, determine the flux density inside the coil.

Problem 157: A given magnetic circuit has a magnetic field intensity of 400 AT/m. If the length of the magnetic path is doubled maintaining the same magnetomotive force, how much is the new magnetic field intensity?

Problem 158: A magnetic circuit consists of silicon steel of 3000 permeability, of 10 cm length and a cross section of 1.5 sq. cm and an air gap of the same cross section and of 2 cm length. A 1/2-ampere current flows through the 5000-turn coil. What is the field intensity at the air gap?

Problem 159: A magnetomotive force is supplied by a current of one ampere through 100 turns. The magnetic circuit consists of a steel core of 1000 permeability, 10 cm long and 4 sq. cm area and an air gap one cm long. What is the field intensity at the air gap?

Problem 160: A circular ring of iron having a cross sectional area of \(5\,cm^2\), an average diameter of 30 cm is wound with a coil of 1000 turns. If a current of 3 A is pass through the coil, determine the flux generated? Assume the relative permittivity of iron is 250.

Problem 161: A non-magnetic ring having a cross sectional area of \(10\,cm^2\) is uniformly wound with 300 turns of a given wire. If a current of 1 A is passed through the coil, \(2.4\,\mu Wb\) of flux is generated inside the ring. Determine the average diameter of the ring.

Problem 162: A coil with 150 turns is wound over a 200 cm cylindrical iron core whose relative permittivity is 250. If a current of 2 A is pass through the coil, determine the flux density in the core.

Problem 163: A magnetic circuit consists of silicon steel of 3000 permeability and an air gap. The length of the steel core is 10 cm and the air gap is 2 cm. Both have the same cross section of 1.5 sq. cm. A current of 1/2 ampere flows through the windings to produce 2351 maxwells flux. How many turns are there in the coil?

Problem 164: A toroidal core with a mean circumference of 100 cm and a cross sectional area of \(10\,cm^2\) is wound with 500 turns of wire. What current would be required to generate a flux of 1 mWb in the core. Assume the core has a relative permeability of 800.