12th class (Fsc) Physics unit 1 MCQs
chapter 1 MCQs 12th Class Physics
Electrostatics:
1. The SI unit of relative permitivity is:
a. Nm2c-2
b. Nm-1
c. no unit
d. C2 N-1 m-2
2. The electrostatic force of repulsion between two electrons at a distance 1 m is:
a. 2.3 x 10-28N
b. 2.3 x 10-24N
c. 2.3 X 10-30N
d. 2.3 X 10-26N
3. The electrostatic force between two charges is 42N. If we place a dielectric of εr = 2.1 between the charges then the force become equal to:88.2N
a. 20N
b. 42N
c. 2N
d. 88.2N
4. The force between two-point charges separated by air in 4N when separated by a medium of relative permittivity 2, the force between them become:
a. 4N
b. 1/2N
c. 8N
d. 2N
5. SI unit of relative permittivity is:
a. Nm-2
b. C2/Nm2
c. C-2/Nm2
d. None of these
6. If the distance between the two charges bodies is halved, the force between them
becomes:
a. Four times
b. Double
c. One fourth
d. Half
7. If the medium between the charges is not free space then electrostatic force will:
a. Remain same
b. Increase
c. Decrease
d. None of these
8. For which material medium, force between two charges particles is maximum?
a. Mica
b. Ammonia
c. Teflon
d. Germanium
9. If both the magnitude of charges and distance between them is doubled, then coulombs’ force will be:
a. Remain same
b. Doubled
c. One fourth
d. Half
10. The number of electrons in one coulomb charge is equal to:
a. 6.25 x 1018
b. 1.6 x 10-8
c. 6.25 x 1019
d. 6.25 x 10-19
11. Relative permittivity for air is:
a. 1.0006
b. 1.06
c. 1.6
d. 1.006
12. The direction of field lines around an isolated negative charge ‘-q’ is:
a. Elliptical
b. Radically inward
c. Circular
d. Radically outward
13. One coulomb charge contains the number of electrons:
a. 6.25×1018
b. 1.6×10-19
c. 6.25×1019
d. 6.25×10-19
14. The force between two similar unit charges placed one meter apart in air is:
a. 9 x 109N
b. Zero
c. 9 X 10-9N
d. One newton
15.The constant of proportionality “k” depend upon:
a. Nature of bodies
b. Nature of medium between two charges
c. Nature of medium between two charges and system of units
d. The system of units
16. Two charges 1 µC and 5 µC separated by 20cm, the ratio of electoral forces acting on them will be:
a. 1:1
b. 1:2
c. 5:1
d. 1:5
17. Two opposite point charge of same magnitude separated by distance 2d, electric potential mid-way between them is:
a. Zero
b. 1V
c. 5V
d. 2V
19. The electrostatic force between two charges is 42N. if we place a dielectric of
ε r = 2.1 between the charges, then the force become equal to:
a. 20 N
b. 42N
c. 2
d. 88.2 N
20. If electric and gravitational forces on an electron balance each other, then electricity intensity will be:
a. E = Fe/q
b. E = mg/q
c. E = 1/4πεo q/r2
d. E = mg/q
21. If the distance between two charges is halved and charges are also doubled, then force between them will be:
a. Eight times
b. Two times
c. Sixteen times
d. Four times
22. The force between two charges is 28N. if Paraffin Wax of relative permittivity 2.8 is introduced between the charges as medium, then the force reduces to:
a. 15 N
b. 25 N
c. 10 N
d. 20 N
23. RC factor has same dimensions as that of:
a. Time
b. Potential difference
c. Capacitance
d. Resistance
24. Electric intensity inside the hollow sphere is:
a. 1/εo
b. σ/εo
c. Zero
d. σ/2εo
25. Which one of the following can be taken as measure of electric field intensity?
a. qA/εo
b. F/A
c. Φεo/A
d. Φε/A