The substances which have a large number of free electrons and offer a low resistance are called:

 

1. The substances which have a large number of free electrons and offer a low resistance are called:
2. (a) insulators (b) inductors (c) semi-conductors (d) conductors Answer: (d)
3. Which of the following materials has a negative temperature co-efficient of resistance? (a) Copper (b) Aluminum (c) Carbon (d) Brass Answer: (c)
4. Kirchhoff's law is applicable to: (a) passive networks only (b) a.c. circuits only (c) d.c. circuits only (d) both a.c. as well d.c. circuits Answer: (d)
5. A capacitor stores 0.24 coulombs at 10 volts. Its capacitance is: (a) 0.024 F (b) 0.12 F (c) 0.6 F (d) 0.8 F Answer: (a)
6. The dielectric constant for mica is nearly: (a) 200 (b) 100 (c) 3 to 8 (d) 1 to 2 Answer: (c)
7. Tesla is a unit of: (a) field strength (b) inductance (c) flux density (d) flux Answer: (c)
8. Aluminium and platinum are _____ materials. (a) ferromagnetic (b) diamagnetic (c) paramagnetic (d) insulating Answer: (c)
9. Relative permeability of vacuum is: (a) 1 (b) 1 H/m (c) 1/4π (d) 4π × 10⁻⁷ H/m Answer: (a)
10. Active materials of a lead acid cell are: (a) spongy lead (b) lead peroxide (c) dilute H₂SO₄ (d) all of the above Answer: (d)
11. Laminations of a D.C. generator core are generally made of: (a) case iron (b) carbon (c) silicon steel (d) solvent steel Answer: (c)