Materials and Components Questions

• Curie Weiss law is .
• Electrical contact materials used in switches, brushes, relay must possess
• The unit for mmf is
• If a small amount of Cu is added to Ni conductor, then
• A conductor carries 10 A current in + x direction and is lying in a field having a flux density 0.2 T directed along + z direction. The magnitude of force per metre length and direction are
• The core of a solenoid is made of material of relative permeability μr. A small cavity area dA and length dl is cut in the core. If it is desired that flux density in the cavity should be equal to B0
• Assertion (A): Hall effect is used to determine whether the semi- conductor is p or n type. Reason (R): Under the influence of field, holes and electrons move in opposite direction.
• In terms of Planck's constant h, the orbital angular momentum of an electron is
• The induced magnetic dipole moment is independent of the permanent magnetic dipole moment.
• When a material is in superconducting state and a magnetic field is applied
• Nickel is a non-magnetic material.
• An electron is moving around a proton, in a circle of radius R. If flux density in the region is increased from zero to B, the force on the electron is
• A copper specimen has resistivity equal to 1.8 x 10-8 ohm-m at room temperature. At a temperature of 700 K, the resistivity is likely to be
• The number of protons in a silicon atom are
• A rare gas having N atoms/m3 is subjected to an electric field E. The electric dipole moment per unit volume is proportional to N and E.
• As the atoms of rare gases become larger, electronic polarizability
• Carbon steel has a residual flux density of 1 Wb/m2.
• Assertion (A): Dielectric constant is independent of temperature unless the temperature is extremely high. Reason (R): For normal temperatures the number of atoms per unit volume is constant.
• The fact that domains exhibits spontaneous magnetisation is
• The number of protons in a copper atom are