CURRICULAM 2021-22 

LABORATORY MANUAL (XII) 

HOT POTATOES WORK 

Google classroom material 

 

Alternating Current

 

KENDRIYA VIDYALAYA JAMALPUR

SECOND MONTHLY TEST

PHYSICS (XII B)

CHAPTER-I (10 MARKS) & CHAPTER -II (30 MARKS)

Time allowed : 90 minutes (Date of exam : 10/07/2020)

 

1.       Which of the following statements is incorrect?                 (1)

(a)    The net charge inside a conductor is zero in electrostatic conditions.

(b)    Electric field inside a conductor is zero in electrostatic conditions.

(c)     Electric potential is zero inside the conductor in electrostatic conditions.

(d)    Electric field inside a metallic cavity is always zero.

 

2.       Write the expression of electric field due to a dipole of dipole moment p at a distance 2d at an equatorial point.                                                                    (2)

 

3.       A positive charge Q is placed in uniform electric field E directed along positive x-axis.       (1+1+2)

(a)    What is the direction in which Q will experience electrostatic force?

(b)    How does the electrostatic potential energy of Q change with time?

(c)     After traveling a distance of x metres, find the change in electrostatic potential energy.

 

4.       Three capacitors of equal capacitances C are connected in series. Find the equivalent capacitance. How would equivalent capacitance change if the plates of middle capacitor are connected by metallic wire?  (2+1 =3)

 

5.       (a) Find the net Coulombic force on charge Q.

 

(b) Find the electric potential energy of the system.

                                                                                               

 

                                                                                (2 +2 =4)

 

 

 

6.       Using Gauss’s law, find the flux and electric field due to a line distribution of charge of charge density λ (consider line density to be uniform) at a perpendicular distance R.  (5)

 

7.       What happens to an electric dipole placed in a uniform electric field? If the dipole moment of the dipole makes angle θ with the direction of electric field, Write the expression of torque and potential energy of the dipole. [consider that PE of the dipole is 0 when θ = 90⁰ ]  (3)

 

8.       Derive an expression of work done (without acceleration) in bringing a unit positive charge q from infinity to a point inside the electric field of charge Q. Using this expression and work potential energy theorem, write the expression of potential energy. (4)

 

9.       Find the equivalent capacitance of the following combination between A and B:- (4)

 

 

 

 

 

10.   Derive an expression of potential energy stored in a capacitor of capacitance C when it is charged to a potential of V volts.                                                                                         (4)

 

11.   (a)What are dielectrics? (1)

(b)How does a dielectric of dielectric constant K change the capacitance of a capacitor when it is                 completely inserted into the volume inside a parallel plate capacitor of capacitance C?  (1)

(d)    Find the capacitance of the capacitor shown in the diagram: - (4)

 

 

 

 

 

MY WORK ON ONLINE COURSE OF ZIET MUMBAI

 PHYSICS VIDEOS

1.       https://youtu.be/D5QU7asYeto  ( EFFECT OF EDDY CURRENT) 2.

 

     CURRENT ELECTRICITY QUIZ

 

1. The resistance of a conductor depends on

a) the potential difference across its ends.

b) the current through the conductor.

c) geometry of the conductor

d) none of these

 

2. A wire of length L and resistance R is cut into two equal halves. The resistance of the wire of length L/2 will be

a) R/2

b) 2R

c) R/4

d) 4R

 

3. Individual electrons in a metal under the influence of electric field

a) move in a zig- zag but straight-line path

b) move in a zig-zag but curved path

c) move in straight line in the direction of electric field

d) move in straight line in the direction opposite to electric field

 

4. In the phrase " drift velocity of electrons in metal" , drift velocity means

a) average velocity of all electrons crossing a given cross-section area in a metal

b) distance traveled by an individual electrons per unit time

c) distance traveled by a group of electrons crossing a given perpendicular area per unit time

d) none of these

 

5. The mobility of electrons in a metal is independent of

a) electric field

b) drift velocity

c) potential difference

d) all of the above

 

6. Resistivity of a semiconductor

a) increases with temperature.

b) decreases with temperature.

c) remains constant with temperature.

d) first remains constant for smaller change in temperature and then decreases with temperature

 

7. Three resistors of resistances R, 2R and 3R are connected in series. The potential differences between the resistors will be in the ratio

a) 1:1:1

b) 1:2:3

c) 3:2:1

d) 1:4:9

 

8. EMF of a cell is

a) the force applied to charges inside cells during chemical reaction.

b) the maximum potential difference between the terminals of the cell in open circuit condition

c) the potential difference offered by cell during the drift motion of electrons in the circuit

d) work done by cell to move electrons in the circuit.

 

9. Two equal resistors are connected first in series and then in parallel to the same battery. The power consumed in the two cases

a) would be equal.

b) would be more for series connection.

c) would be more for parallel connection.

 

10. Potentiometer is a device which is used to measure

a) emf of a cell

b) internal resistance of a cell

c) potential difference across a cell

d) all of the above