#### 12th Standard Physics Electrostatics English Medium Free Online Test One Mark questions 2020-2021

12th Standard

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Physics

Time : 00:20:00 Hrs
Total Marks : 20
20 x 1 = 20
1. Which charge configuration produces a uniform electric field?

(a)

point Charge

(b)

infinite uniform line charge

(c)

uniformly charged infinite plane

(d)

uniformly charged spherical shell

2. A thin conducting spherical shell of radius R has a charge Q which is uniformly distributed on its surface. The correct plot for electrostatic potential due to this spherical shell is

(a)

(b)

(c)

(d)

3. Three capacitors are connected in triangle as shown in the figure. The equivalent capacitance between the points A and C is

(a)

1μF

(b)

2μF

(c)

3μF

(d)

$\frac{1}{4}$μF

4. In a hydrogen atom the electron revolves around the proton in an orbit of 0.53 $\mathring { A }$. The potential produced by the electron on the nuleus is

(a)

6.8 V

(b)

13.6 V

(c)

54.4 V

(d)

27.2 V

5. The electric field created by a _________ is basically a non-uniform electric field.

(a)

Test charge

(b)

Positive charge

(c)

Negative charge

(d)

Point charge

6. The expression for the electric field due to a surface of total charge 'Q' is given by

(a)

$\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { \sigma dA }{ { r }^{ 2 } } } \hat { r }$

(b)

$\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { \rho dA }{ { r }^{ 2 } } } \hat { r }$

(c)

$\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { \lambda dl }{ { r }^{ 2 } } } \hat { r }$

(d)

$\overset { \rightarrow }{ E } =\frac { 1 }{ 4\pi { \varepsilon }_{ 0 } } \int { \frac { dq }{ { r }^{ 2 } } } \hat { r }$

7. The unit for electric flux is

(a)

C2N-1m-2

(b)

Nm2C-2

(c)

Nm2C-1

(d)

Nm-2C-1

8. In the given cricuit the effective capacitance between A and B will be

(a)

3μf

(b)

$\frac{36}{13}$ μf

(c)

13μf

(d)

7μf

9. In tuning radio we use,

(a)

capacitors

(b)

transistors

(c)

diodes

(d)

LEDS

10. Two identical metal balls with charges +2Q and -Q are separated by some distance and exerts a force F on each other. They are joined by a conducting wire, which is then removed. The force between them will now.

(a)

F/8

(b)

F/12

(c)

F

(d)

F/4

11. One Joule per Coulomb is called

(a)

Gauss

(b)

ampere

(c)

(d)

volt

12. A condenser of 2μF capacitance is charged steadily from 0 to 5 coulomb. Which of the following graphs correctly represents the variation of potential difference across its plates with respect to the charge on the condensor [Q = C V ]

(a)

(b)

(c)

(d)

13. A charge q is placed at the centre of a cubical box of side with top open. The flux of electric field through the surface of the cubical box is

(a)

Zero

(b)

$\frac { q }{ { \varepsilon }_{ 0 } }$

(c)

$\frac { q }{ 6{ \varepsilon }_{ 0 } }$

(d)

$\\ \frac { 5q }{ 6{ \varepsilon }_{ 0 } }$

14. Find the electric field at x =5m from the graph.

(a)

2 V/m

(b)

-2.5 V/m

(c)

2/5 V/m

(d)

-2/5 V/m

15. Which instrument was used to demonstrate the electrostatic shielding?

(a)

Lightning arrester

(b)

Van de graaff generator

(c)

(d)

Gold leaf electroscope

16. The force between two charges at a particular distance in air is 36 N. If the distance between the charges is filled by a medium of dielectric constant 6, then the force is__________.

(a)

216 N

(b)

6 N

(c)

30 N

(d)

24 N

17. Which one of the following relation is correct?

(a)

V=$\frac{q}{C}$

(b)

C=q tan q

(c)

V=qC

(d)

$\frac{V}{C}$

18. Two point charges +q and -q are placed at points A and B respectively separated by a small distance. The electric field intensity at the midpoint O of AB :

(a)

is zero

(b)

acts along AB

(c)

acts along BA

(d)

acts perpendicular to AB

19. The torque (-ፒ) experienced by an electric dipole placed in a uniform electric field (E) at an angle θ with the field is

(a)

pEcosθ

(b)

pE cosθ

(c)

pE sinθ

(d)

2pE sinθ

20. When an electric dipole of dipole moment p is aligned parallel to the electric field E then the potential energy of the dipole is given as _________.

(a)

pE

(b)

zero

(c)

-pE

(d)

$\frac{pE}{\sqrt{2}}$