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

12th Standard

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Physics

Time : 00:20:00 Hrs
Total Marks : 20
20 x 1 = 20
1. What is the ratio of the charges $\left| \frac { { q }_{ 1 } }{ { q }_{ 2 } } \right|$ for the following electric field line pattern?

(a)

$\frac { 1 }{ 5 }$

(b)

$\frac { 25 }{ 11 }$

(c)

5

(d)

$\frac { 11 }{ 25 }$

2. Four Gaussian surfaces are given below with charges inside each Gaussian surface. Rank the electric fl ux through each Gaussian surface in increasing order.

(a)

D < C < B < A

(b)

A < B = C < D

(c)

C < A = B < D

(d)

D > C > B > A

3. The total electric fl ux for the following closed surface which is kept inside water

(a)

$\frac { 80q }{ { \varepsilon }_{ 0 } }$

(b)

$\frac { q }{ { 40\varepsilon }_{ 0 } }$

(c)

$\frac { q }{ { 80\varepsilon }_{ 0 } }$

(d)

$\frac { q }{ { 160\varepsilon }_{ 0 } }$

4. Rank the electrostatic potential energies for the given system of charges in increasing order.

(a)

1 = 4 < 2 < 3

(b)

2 = 4 < 3 < 1

(c)

2 = 3 < 1 < 4

(d)

3 < 1 < 2 < 4

5. 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

6. _______ and Coulomb's law form fundamental principles of electrostatics

(a)

Newton's law of gravitation

(b)

superposition principle

(c)

ohm's law

(d)

Kepler's law

7. An uncharged metal sphere is placed between two equal and oppositely charged metal plates. The nature of lines of force will be

(a)

(b)

(c)

(d)

8. The force experienced by a unit charge is called

(a)

Electric potential

(b)

Electric flux

(c)

Electric field

(d)

Static electricity

9. The electric potential V as a function of distance x (metres) is given by V = ( 5x2 + 10x -9) volt. The value of electric field at a point x = 1m is

(a)

20 Vm-1

(b)

6 Vm-1

(c)

11 Vm-1

(d)

-23 Vm-1

10. Four plates each of area 'N. and inferplate separation 'd' are placed as shown in figure. The two inner plates are connected to the point 'B' and outer to point 'A'. What is equivalent capacitance?

(a)

$\frac { { \varepsilon }_{ 0 }A }{ d } \\$

(b)

$\frac { {2 \varepsilon }_{ 0 }A }{ d } \\$

(c)

$\frac { {3 \varepsilon }_{ 0 }A }{ d } \\$

(d)

$\frac { {4 \varepsilon }_{ 0 }A }{ d } \\$

11. The magnitude of electric dipole moment of water molecule is

(a)

6 x 10-30 cm

(b)

6.2 x 10-30 cm

(c)

6.1 x 10-30

(d)

5.95 10-30 cm

12. A non-conducting material which has no free electrons is called

(a)

capacitor

(b)

Dielectric

(c)

conductor

(d)

Inductor

13. The lower comb of van de graaff generator is maintained at a positive potential of

(a)

10 kV

(b)

107 V

(c)

100 V

(d)

103 V

14. Dielectric constant for the metals is

(a)

Zero

(b)

>1

(c)

<1

(d)

Infinite

15. Which of the following statement on equipotential surface is wrong?

(a)

The potential difference between any two points on the surface, is zero.

(b)

The electric field is always perpendicular to the surface

(c)

Equipotential surface is always spherical.

(d)

No work is done in moving a charge along the surface

16. Charge Q is divided into two parts which are then kept some distance apart. The force between them will be maximum if the two parts are

(a)

$\frac{Q}{2}$ each

(b)

each $\frac{Q}{5}$

(c)

$\frac{Q}{3}$and$\frac{2Q}{3}$

(d)

$\frac{Q}{4}$and$\frac{3Q}{4}$

17. During charging a capacitor variation of potential V of the capacitor with time t as shown a

(a)

(b)

(c)

(d)

18. 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)

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

19. A charge q1 exerts force on charge q2. If another charge q3 is brought near, the force of q1, exerted on q2, will be

(a)

decreased

(b)

increased

(c)

remains unchanged

(d)

increased if q3 is of same sign as q1 and decreased if q2 is of opposite sign.

20. Van de Graaff generator produces an electrostatic potential difference of_______ volts.

(a)

108

(b)

109

(c)

107

(d)

1010