📡 Electronics and Communication Engineering (ECE) Solved MCQs with Answers

Practice 406 approved 📡 Electronics and Communication Engineering (ECE) questions with verified answers from the 🛠️ Engineering Essentials subject for Pakistan exams.

406 solved MCQs

Diamond is a paramagnetic material.Answer: False Which capacitor-store higher amount of energy?Answer: Mica capacitor Above ferroelectric curie temperature, spontaneous polarization in ferroelectric materials becomes stronger.Answer: False In paramagnetic materialsAnswer: permanent magnetic dipoles exist but the interaction between neighbouring dipoles is negligible Assertion (A): Atomic number of sodium is 11. Reason (R): Sodium has a body centred cubic lattice.Answer: Both A and R are true but R is not correct explanation of A The conductivity of intrinsic semiconductor is given byAnswer: eni(μp + μn) The core of a coil has a length of 10 cm. The self inductance is 8 mH. If the core length is doubled, all other quantities remaining the same, the self inductance will beAnswer: 4 mH Assertion (A): Electronic and Ionic polarization in a polyatomic gas are independent of temperature. Reason (R): The orientation polarization is independent of temperature.Answer: A is true but R is false Two materials having temperature coefficients of 0.004 and 0.0004 respectively are joined in series. The overall temperature coefficient is likely to beAnswer: 0.001 The number of valence electrons in pentavalent impurity isAnswer: 5 If the diameter of a wire is doubled, its current carrying capacity becomesAnswer: four times The law J = σE, where J is current density, σ is electrical conductivity and E is field strength isAnswer: Ohm's law Assertion (A): Silicon is less sensitive to changes in temperature than germanium. Reason (R): Cut in voltage in silicon is less than that in germanium.Answer: A is true but R is false Material which lack permanent magnetic dipoles are known asAnswer: diamagnetic A parallel plate capacitor has its length, width and separation doubled. It fringing effects are neglected, to keep the capacitance same, the dielectric constant must beAnswer: halved Assertion (A): In imperfect capacitors, the current does not lead the applied ac voltage by 90°. Reason (R): When subjected to ac fields, the dielectric constant can be expressed as ∈'r - j∈"r.Answer: Both A and R are true and R is correct explanation of A In atomic physics, a state with l = 0 is called p state.Answer: False If a sample of germanium and a sample of silicon have the same impurity density and are kept at room temperatureAnswer: resistivity of silicon will be higher than that of germanium When an electric field E is applied to solid and liquid insulating materials, the internal field Ei acting at the location of atom is such thatAnswer: Ei > E Which element exhibits the property of inertia?Answer: Inductance For a permanent magnetic materialAnswer: the residual induction and coercive field should be large In a coaxial cable, braided copper is used forAnswer: shield The hysteresis phenomenon in ferromagnetic materials exists at all temperatures.Answer: False Assertion (A): Magnetic susceptibility of diamagnetic materials is much less than that of paramagnetic materials. Reason (R): For diamagnetic as well as paramagnetic materials, μr is nearly equal to 1.Answer: Both A and R are true and R is correct explanation of A The attraction between the nucleus and valence electron of copper atom isAnswer: weak If the temperature of an extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, thenAnswer: both the majority and minority carrier densities double There is no hysteresis phenomenon is any dielectric material.Answer: False In metals the valence electron wave functions are strongly perturbed by the presence of neighbouring atoms.Answer: True For a paramagnetic material, susceptiblity increases with increasing temperature.Answer: False Hydrogen is used inAnswer: large size generators