ESE (IES) Electrical Engineering P1 2013

Direction: In the following question two statements, one labeled as the ‘Statement (I)’ and the other as ‘Statement (II)’. You are to examine these two statements carefully and select the answers to these items using the codes given below:
Statement (I): The Dielectric constant of a substance, under the influence of alternating electric fields is, in general, a ‘complex’ quantity. Statement (II): The ‘imaginary’ part of the Dielectric constant is a measure of the dielectric loss in the substance.

Statement (I) : A large number of metals become superconducting below a certain temperature which is characteristic of the particular metal. Statement(II) : Superconducting compounds andalloy must have components which are themselves superconducting.

Statement (1): Electrostriction occurs due topiezoelectricity which in the reverse effect i.e. the production of polarization on application of mechanical stress if the lattice has no centre of symmetry. Statement (II): When an electric field is applied to a substance it becomes polarized, the electrons and nuclei assume new geometric positions and the mechanical dimensions of the substance are altered.

Statement (|) : By measuring the half-effect voltage, one can determine: A) The strength of the field in terms of the current, or B) The current in terms of the field. Statement (||) : In the case of a semiconductor, the mobility of the carriers can be determined by using (b), so long as only one kind of carrier is present.

Statement (i): In an ac dynamometer type wattmeter the instantaneous value of developed deflecting torque is proportional to the product of voltage and current in the respective coils at the corresponding instant, the constant of proportionality being the same as in the case of dc use. Statement (ii): The moving system of the meter is prevented by its inertia from following the variations in the deflecting torque which takes place during each cycle, and takes up a position corresponding to the average value of the torque. Codes :

Statement (i): Electrostatic wattmeter is not widely used commercially because of its inability to measure power of high value. Statement (ii): It is used mainly for very small power measurement at high voltages and low power factors.