1. The conductivity of intrinsic semiconductor is given by
2. 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 be
3. The minority carrier life time and diffusion constant in a semiconducting material are 100 μs and 100 cm2/s respectively. The diffusion length of carriers is
4. Assertion (A): Electronic and Ionic polarization in a polyatomic gas are independent of temperature.Reason (R): The orientation polarization is independent of temperature.
5. Two materials having temperature coefficients of 0.004 and 0.0004 respectively are joined in series. The overall temperature coefficient is likely to be
6. The number of valence electrons in pentavalent impurity is
7. If the diameter of a wire is doubled, its current carrying capacity becomes
8. The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is
9. 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.
10. Material which lack permanent magnetic dipoles are known as
11. 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 be
12. 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.
13. In atomic physics, a state with l = 0 is called p state.
14. If a sample of germanium and a sample of silicon have the same impurity density and are kept at room temperature
15. 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 that
16. Which element exhibits the property of inertia?
17. For a permanent magnetic material
18. In a coaxial cable, braided copper is used for
19. The hysteresis phenomenon in ferromagnetic materials exists at all temperatures.
20. 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.
21. The attraction between the nucleus and valence electron of copper atom is
22. If the temperature of an extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then
23. There is no hysteresis phenomenon is any dielectric material.
24. The units of μ0 and μr are
25. In metals the valence electron wave functions are strongly perturbed by the presence of neighbouring atoms.