### Basic Electrical Science (Electrostatics)

1. The unit of absolute permittivity of a
medium is
(a) joule/coulomb
(b) Newton-metre

2. If relative permittivity of mica is 5, its absolute permittivity is
(a) 5 ε0
(b) 5/ε0
(c) ε0/5
(d) 8.854 × 10-12

3. Two similar electric charges of 1 C each are placed 1 m apart in air. Force of repulsion between them would be nearly...... newton
(a) 1
(b) 9 × 109
(c) 4 π
(d) 8.854 × 10-12

4. Electric flux emanating from an electric charge of + Q coulomb is
(a) Q/ε0
(b) Q/εr
(c) Q/ε0εr
(d) Q

5. The unit of electric intensity is
(a) joule/coulomb
(b) Newton/coulomb
(c) volt/metre
(d) both (b) and (c)

6. If D is the electric flux density, then value of electric intensity in air is
(a) D/ε0
(b) D/ε0εr
(c) dV/dt
(d) Q/εA

7. For any medium, electric flux density D is related to electric intensity E by the equation
(a) D = ε0 E
(b) D = ε0εr E
(c) D = E/ε0εr
(d) D = ε0E/εr

8. Inside a conducting sphere,...remains constant
(a) electric flux
(b) electric intensity
(c) charge
(d) potential

9. The SI unit of electric intensity is
(a) N/m
(b) V/m
(c) N/C
(d) either (b) or (c)

10. According to Gauss’s theorem, the surface integral of the normal component of electric flux density D over a closed surface containing charge Q is
(a) Q
(b) Q/ε0
(c) ε0Q
(d) Q20

11. Which of the following is zero inside a charged conducting sphere ?
(a) potential
(b) electric intensity
(c) both (a) and (b)
(d) both (b) and (c)

12. In practice, earth is chosen as a place of zero electric potential because it
(a) is non-conducting
(b) is easily available
(c) keeps losing and gaining electric charge every day
(d) has almost constant potential.