Which of the following gives materials in order of decreasing values of permeability? Cobalt, nickel, aluminium, iron. Pure iron, silicon iron, aluminium, bismuth. Silver, copper, aluminium, iron. Permalloy, nickel, air, water. TRUE ANSWER : ? YOUR ANSWER : ?
A degaussing is the process of removing gases from materials. demagnetising metallic parts. remagnetising metallic parts. removal of magnetic impurities. TRUE ANSWER : ? YOUR ANSWER : ?
What is the value of dielectric constant of air? 0. 1. Less than 1 none of these. TRUE ANSWER : ? YOUR ANSWER : ?
In order to minimise loss due to hysteresis, the magnetic material should have large B-H loop area. low hysteresis coefficient. high resistivity. high retentivity. TRUE ANSWER : ? YOUR ANSWER : ?
According to the Bohr model, an electron gains or losses energy only by moving faster or slower in an allowed orbit. jumping from one atom to another atom. being completely removed from an atom. jumping from one allowed orbit to another. TRUE ANSWER : ? YOUR ANSWER : ?
Which of the following is the example for piezo-electric material ? Lead zirconate titanate Potassium niobate Copper None of these TRUE ANSWER : ? YOUR ANSWER : ?
Which of the following is the least desired property in magnetic materials for electrical engineering applications ? Large hysteresis loop. High electrical resistivity. High magnetic permeability. All of these TRUE ANSWER : ? YOUR ANSWER : ?
The intensity of magnetization, M, of a ferro magnetic solid decreases with increasing temperature. is independent of temperature. increases with increasing temperature. depends on method of heating. TRUE ANSWER : ? YOUR ANSWER : ?
Substance having permeability less than the permeability of free space, are known as paramagnetic. bipolar. ferromagnetic. diamagnetic. TRUE ANSWER : ? YOUR ANSWER : ?
The numberof atoms per unit cell in a B.C.C structure is 7. 4. 12. 2. TRUE ANSWER : ? YOUR ANSWER : ?