XII Physics Electrostatics Online Test Mdcat-2024

1. If the distance between the two point charges become half then force between them becomes______________?

2. Potential difference across the capacitor of capacitance of 4.5μF is:a. 8/3V
b. 8/5V
c. 4V
d. 8V

3. Total capacitance between points A and B is:

a. C
b. 3C
c. C/3
d. 3C/2

4. A metallic sphere of diameter 10m is charged so that the potential on its surface is 50V, potential on its centre would be:
a. 5 V
b. 50 V
c. 100 V
d. 500 V

5. If charge on capacitor is doubled then it’s capacitance would be:
a. Double
b. Triple
c. Quadruple
d. Remain same

6. In a parallel-plate capacitor with plate area A and charge Q, the force on one plate because of the charge on the other is equal to:
a. Q²/2€A
b. Q²/2€A²
c. Q²/€A
d. Q²/€A²

7. Which one of the following is equal to one Volt:
a. One Newton per coulomb
b. One Joule per coulomb
c. One dyne per coulomb
d. One horse power per second

8. Three charges q , Q and 4q are placed in a straight line of length "L" at a points distance 0 , L/2 and L respectively from one end. In order to make the net force on "q" zero, the charge "Q" must be equal to:
a. -2q
b. -1/2q
c. -q
d. q

9. The ratio of the force between two small spheres with constant charges (A) in air, (B) in a medium of dielectric constant K is:
a. K²:1
b. 1:K²
c. K:1
d. 1:K

10. Electric potential energy in parallel plate capacitor is stored in/at:
a. Between the plates
b. On the plates
c. Either side of plates
d. Corners of plates

11. By putting dielectric in medium between two charges or charged plates, force and capacitance:
a. Increase , decrease
b. Decrease, increase
c. Increase, increase
d. Decrease, decrease

12. Electric intensity at infinite distance from point charge is:
a. Positive
b. Negative
c. Maximum
d. Zero

13. Electric field can deflect:
a. Neutron
b. X-rays
c. Alpha rays
d. Gamma rays

14. Potential energy of a charge increases by 40J when is brought form potential of 500V to 300V, Coulomb charge on it is:
a. 10 C
b. 5 C
c. 0.1C
d. 0.2C

15. A Q Coulomb charge is divided into two parts, force between them would be greater when magnitude of charge on each charge is:
a. Q/3 , 2Q/3
b. Q/4 , 3Q/4
c. Q/2 , Q/2
d. 3Q/7, 4Q/7

16. The negative of potential gradient is equal to:
a. Potential energy
b. Potential difference
c. Electric field intensity
d. Electromotive force

17. Phenomena in which a charged body attract uncharged body is called:
a. Magnetic induction
b. Electrostatic Induction
c. Charge movement
d. Charge distribution

18. Electric field due to uniformly charged sphere is zero:
a. Everywhere
b. Outside the shell
c. Inside the shell
d. On center

19. The electric field at a distance of 10 cm from an isolated point particle with a charge of 2×10−9 C
is:
a. 18 N/C
b. 180 N/C
c. 1800 N/C
d. 1000 N/C

20. Which of the following is unit of the electric field is:
a. N.C²
b. N/C²
c. C/V
d. V/m

21. Two identical charges, 2.0 m apart, exert forces of magnitude 4.0 N on each other. Amount of charge on either:
a. 1.9 × 10^5 C
b. 4.2 x 10^-5 C
c. 1.8 x 10^-9 C
d. 2.1 x 10^-5 C

22. Two small charged objects attract each other with a force F when separated by a distance
d. If the charge on each object is reduced to one-fourth of its original value and the distance d between them is shorted to d/2, then the force becomes:
a.F/4
b. F/8
c. F/16
d. F/32

23. A positively charged metal sphere A is brought into contact with an uncharged metal sphere B. As a result:
a. A is positively charged and B is neutral
b. A is positively charged and B is negatively charged
c. A is neutral and B is positively charged
d. both spheres are positively charged

24. The diagram shows two pairs of heavily charged plastic cubes. Cubes 1 and 2 attract each
other and cubes 1 and 3 repel each other. 

Which of the following illustrates the forces of cube 2 on cube 3 and cube 3 on cube 2?

25. To make an uncharged object have a negative charge we must:
a. add some atoms
b. remove some atoms
c. add some electrons
d. remove some electrons

26. Two points are shown in a field, tick the correct about potential gradient at these points:

a. Va > Vb
b. Ea < Eb
c. Va < Vb
d. Ea > Eb

27. In series combination of capacitors, equivalent capacitance is:
a. Less than the largest individual capacitance
b. Less than the smallest individual capacitance
c. Equal to average capacitance
d. Greater than the largest individual capacitance

28. Due to electric polarization, potential difference and electric field between the plates of capacitor_______ and capacitance_______:
a. Decreases, increases
b. Increases, decrease
c. Remains unchanged , increases
d. Increases then deceases, decreases

29. How three capacitors of 2 μF each have to be connected to have an equivalent capacitance of 3 μF:
a. All the capacitors should be connected in series
b. all the capacitors should be connected in parallel
c. Two capacitors in series and one in parallel
d. Two capacitors in parallel and one in series

30. The force between two charges 1 m apart is 5 N. If each is moved by 0.25 towards the other, then force between them will become :
a. 5N
b. 10N
c. 15N
d. 20N

31. If 5 N is the force between two charges in free space then force between the same two charges having same distance between them in a dielectric medium of relative permittivity 5 is:
a. 1N
b. 5N
c. 4N
d. 25N

32. A parallel plate capacitor has a plate area of 0.2m² and a plate separation of 0.1mm. To obtain an electric field of 2.0 x 10^6 V/m between the plates, the magnitude of the charge on each plate should be:
a. 8.5 μC
b. 2.5 μC
c. 3.5 μC
d. 6 μC

33. The spatial distribution of electric field due to charges (A, B) is shown in figure. Which one of the following statements is correct ?

a.  A is +ve and B –ve, |A| > |B|
b. A is –ve and B +ve, |A| = |B|
c. Both are +ve but A > B
d. Both are –ve but A > B

34. If the magnitude of an electric field at a point is equal to the electric potential at that point, then the distance of point from the charge is
a. 1Meter
b. 3Meter
c. 2Meter
d. 4Meter

35. Which type of capacitor used for tuning radio:
a. Multiplate capacitor
b. Variable capacitor
c. Electrolytic capacitor
d. Parallel plate capacitor

36. A capacitor has a capacitance of 4μF in presence of air. Find the capacitance in μF when a
medium of dielectric constant 8 is placed between the plates:
a. 32
b. 2
c. 16
d. 8

37. If the force between the electron in the first Bohr orbit and the nucleus (proton) in hydrogen atom is F, then the force between them when the electron is in the second orbit is:
a. 4F
b. F/9
c. F/4
d. F/16

38. Field lines for any negative charge are always:
a. Inwards
b. Outwards
c. Curved
d. Straight

39. When a capacitor is connected with DC voltage then it works as:
a. Resistor
b. Inductor
c. Insulator
d. Conductor

40. When a capacitor is connected with AC voltage then its capacitance becomes:
a. Infinite
b. Finite
c. Zero
d. Intermediate

41. Electric field lines of force were discovered by:
a. Newton
b. Faraday
c. Lanz
d. Coulomb

42. Tick the correct about dielectric constant:
a. €(vacuum) < €(air) < €(metal)
b. €(vacuum) > €(air) > €(metal)
c. €(vacuum) > €(air) < €(metal)
d. €(vacuum) < €(air) > €(metal)

43. Dielectric constant for air is:
a. 0
b. 1
c. 1.003
d. 2.5

44. When a metallic plate is put between two oppositely charged plates then force between them will:
a. Increase
b. Decrease
c. Zero
d. Infinite

45. Tick the correct about Coulomb's constant:
a. K(vacuum) < K(air) < K(metal)
b. K(vacuum) > K(air) > K(metal)
c. K(vacuum) > K(air) < K(metal)
d. K(vacuum) < K(air) > K(metal)

46. Usually value of dielectric constant is in between 1-10, it shows that force:
a. Decrease 1-10 times
b. Increase 1-10 times
c. Fluctuates between 1-10 times
d. None

47. Unit of Coulomb's constant is:
a. N.C/m²
b. N.m²/C
c. N.m²/C²
d. C²/N.m²

48. Number of electrons in one-coulomb charge:

a. 1.6 x 10¹⁹
b. 1.6 x 10^-19
c. 6.25 x 10¹⁸
d. 6.02 x 10²³

49. An Aluminum atom is converted into an ion, then its mass will:
a.Increase
b.Decrease
c.Remains same
d.None

50. Coulomb's law is a:
a.Central law
b.Universal law
c.Direct square law
d. Non-fundamental law