KKMishra's Tutorials: H C Verma solutions, ELECTRIC FIELD AND POTENTIAL, OBJECTIVE-I, Chapter-29, Concepts of Physics, Part-II

Electric Field and Potential

OBJECTIVE-I

1. Figure (29-Q2) shows some of the electric field lines corresponding to an electric field. The figure suggests that
Figure for Q-1

(a) E_A > E_B > E_C

(b) E_A = E_B = E_C

(c) E_A = E_C > E_B

(d) E_A = E_C < E_B

Answer: (c).

Explanation: There are an equal number of electric field lines within the same areas at A and C but fewer lines at B.

2. When the separation between two charges is increased the electric potential energy of the charges

(a) increases

(b) decreases

(c) remains the same

(d) may increase or decrease

Answer: (d).

Explanation: Electric potential energy is defined as negative of the work done by the electric forces. If both the charges are of the same nature the work done by the forces is positive and potential energy is negative on increasing the separation. But it will be the opposite if the charges are of a different nature.

3. If a positive charge is shifted from a low potential region to a high potential region, the electric potential energy

(a) increases

(b) decreases

(c) remains the same

(d) may increase or decrease.

Answer: (a).

Explanation: In shifting a positive charge from low potential energy region to high potential energy region work will be done against the electric force, i.e. the work done by the electric force is negative so the potential energy is positive, i.e. the electric potential energy increases.

4. Two equal positive charges are kept at points A and B. The electric potential at the points between A and B (excluding these points) is studied while moving from A to B. The potential

(a) continuously increases

(b) continuously decreases

(c) increases then decrease

(d) decreases then increase.

Answer: (d).

Explanation: Suppose two positive charges q and q are placed at distnce r from each other. Potential at a point P at a diatance x from A (x<r) due to these charges will be

V = q/4πєₒx + q/4πєₒ(r-x)

=(q/4πєₒ){(r-x+x)/x(r-x)}

=qr/4πєₒx(r-x)

differentiating V with respect to x we get

dV/dx =(qr/4πєₒ)[-1/x²(r-x) +1/x(r-x)²]

={qr/4πєₒx(r-x)}[1/(r-x)-1/x]

=qr(2x-r)/4πєₒx²(r-x)²

At x → 0, dV/dx →Infinity(-ve)

at x =r/2, dV/dx = 0,

at x →r, dV/dx →Infinity(+ve)

So the potential first decreases and after x =r/2 it increases.

5. The electric field at the origin is along the positive X-axis. A small circle is drawn with the center at the origin cutting the axes at points A, B, C and D having coordinates (a,0), (0,a), (-a,0), (0,-a) respectively. Out of the points on the periphery of the circle, the potential is minimum at

(a) A

(b) B

(c) C

(d) D.

Answer: (a).

Explanation: Since the potential decreases at the maximum rate along the electric field, the minimum potential among these four will be minimum at the point on the x-axis i.e. at A.

6. If a body is charged by rubbing it, its weight

(a) remains precisely constant

(b) increases slightly

(c) decreases slightly

(d) may increase slightly or may decrease slightly.

Answer: (d).

Explanation: When a body is charged by rubbing, either it gets some electrons from another body to be negatively charged or loses some electrons to be positively charged. So either its weight may increase slightly or decrease slightly due to the elctron transfers.

7. An electric dipole is placed in a uniform electric field. The net electric force on the dipole

(a) is always zero

(b) depends on the orientation of the dipole

(c) can never be zero

(d) depends on the strength of the dipole.

Answer: (a).

Explanation: In a uniform electric field both ends will experience equal and opposite force (because the ends of a diapole have equal and opposite charge) hence the net force on the diapole will always be zero. (But there will be the torque).

8. Consider the situation of the figure (29-Q3). The work done in taking a point charge from P to A is W_A, from P to B is W_B and from P to C is W_C.

(a) W_A <W_B < W_C

(b) W_A > W_B > W_C

(c) W_A = W_B =W_C

(d) None of these

Figure for Q-8

Answer: (c).

Explanation: The three points A, B and C are at equal distances from q. So the potential at each of the three points will be equal. Thus the work done in bringing a point charge from P to these points will be equal.

9. A point charge q is rotated along a circle in the electric field generated by another point charge Q. The work done by the electric field on the rotating charge in one complete revolution is

(a) zero

(b) positive

(c) negative

(d) zero if the charge Q is at the center and nonzero otherwise.

Answer: (a).

Explanation: The work done by the electric field depends upon the final and initial positions, not on the path followed by the charge. In one complete revolution, the rotating charge comes to the same point hence no work is done.

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Links to the Chapters

ALL LINKS

CHAPTER- 29- Electric Field and Potential

Questions for Short Answer

CHAPTER- 28- Heat Transfer

Questions for Short Answer

OBJECTIVE -I

OBJECTIVE - II

EXERCISES - Q1 to Q10

EXERCISES - Q11 to Q20

EXERCISES - Q21 to Q30

EXERCISES - Q31 to Q40

EXERCISES - Q41 to Q50

EXERCISES - Q51 to Q55

CHAPTER- 27-Specific Heat Capacities of Gases

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE -II

EXERCISES - Q1 - Q10

EXERCISES - Q11 - Q20

EXERCISES - Q21 - Q30

EXERCISES - Q31 - Q35

CHAPTER- 26-Laws of Thermodynamics

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q1 to Q10

EXERCISES - Q11 to Q22

CHAPTER- 25-CALORIMETRY

Questions for Short Answer

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q1 to Q10

EXERCISES - Q-11 to Q-18

CHAPTER- 24-Kinetic Theory of Gases

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES- Q1 to 10

EXERCISES- Q11 to 20

EXERCISES- Q21 to 30

EXERCISES- Q31 to Q40

EXERCISES- Q41 to Q50

EXERCISES- Q51 to Q62

CHAPTER- 23 - Heat and Temperature

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES - Q-21 TO Q-34

CHAPTER- 22 - Photometry

Questions for Short Answer

OBJECTIVE - I

OBJECTIVE - II

EXERCISES

CHAPTER- 21 - Speed of Light

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES

CHAPTER- 20 - Dispersion and Spectra

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES

CHAPTER- 19 - Optical Instruments

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q 1 to Q 12

EXERCISES - Q 13 to Q 24

CHAPTER- 18 - Geometrical Optics

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q 1 to Q10

EXERCISES- Q11 to Q20

EXERCISES- Q21 to Q30

EXERCISES- Q31 to Q40

EXERCISES- Q41 to Q50

EXERCISES- Q51 to Q60

EXERCISES- Q61 to Q70

EXERCISES- Q71 TO 79

CHAPTER- 17 - Light Waves

Questions for Short Answers

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q1-Q10

EXERCISES - Q11-Q20

EXERCISES - Q21-Q30

EXERCISES - Q31-Q41

CHAPTER- 16 - Sound Waves

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES -Q-21 TO Q-30

EXERCISES -Q-31 TO Q-40

EXERCISES -Q-41 TO Q-50

EXERCISES -Q-51 TO Q-60

EXERCISES -Q-61 TO Q-70

EXERCISES - Q-71 TO Q-80

EXERCISES - Q-81 TO Q-89

CHAPTER- 15 - Wave Motion and Waves on a String

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES - Q-1 TO Q-10

EXERCISES - Q-11 TO Q-20

EXERCISES - Q-21 TO Q-30

EXERCISES - Q-31 TO Q-40

EXERCISES - Q-41 TO Q-50

EXERCISES - Q-51 TO Q-57

CHAPTER- 14 - Fluid Mechanics

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES- Q-1 TO Q-10

EXERCISES- Q-11 TO Q-20

EXERCISES- Q-21 TO Q-32

CHAPTER- 13 - Fluid Mechanics

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES Q-1 TO Q-10

EXERCISES- Q11 TO Q20

EXERCISES Q-21 TO Q30

EXERCISES Q-31 TO Q35

CHAPTER- 12 - Simple Harmonic Motion

Questions for Short Answers

OBJECTIVE-I

OBJECTIVE-II

EXERCISES- Q1 TO Q10

EXERCISES- Q11 TO Q20

EXERCISES- Q21 TO Q30

EXERCISES- Q31 TO Q40

EXERCISES- Q41 TO Q50

EXERCISES- Q51 TO Q58 (2-Extra Questions)

CHAPTER- 11 - Gravitation

Questions for Short Answers

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q_1 to Q_10

EXERCISES -Q-11 TO Q-20

EXERCISES -Q 21 TO 30

EXERCISES -Q 31 TO 39

CHAPTER- 10 - Rotational Mechanics

Questions for Short Answers

OBJECTIVE - I

OBJECTIVE - II

EXERCISES - Q-1 TO Q-15

EXERCISES - Q-16 TO Q-30

EXERCISES Q-31 TO Q-45

EXERCISES Q-46 TO Q-60

EXERCISES Q-61 TO Q-75

EXERCISES Q-76 TO Q-86

CHAPTER- 9 - Center of Mass, Linear Momentum, Collision

Questions for Short Answers

Objective - I

Objective - II

EXERCISES Q-1 TO Q-10

EXERCISES Q-11TO Q-20

EXERCISES Q-21 TO Q-30

EXERCISES Q-31 TO Q-42

EXERCISES Q-43 TO Q-54

CHAPTER- 8 - Work and Energy

Click here for → Question for Short Answers

Click here for → OBJECTIVE-I

Click here for → OBJECTIVE-II

Click here for → Exercises (1-10)

Click here for → Exercises (11-20)

Click here for → Exercises (21-30)

Click here for → Exercises (31-42)

Click here for → Exercise(43-54)

CHAPTER- 7 - Circular Motion

Click here for → Questions for Short Answer

Click here for → OBJECTIVE-I

Click here for → OBJECTIVE-II

Click here for → EXERCISES (1-10)

Click here for → EXERCISES (11-20)

Click here for → EXERCISES (21-30)

CHAPTER- 6 - Friction

Click here for → Questions for Short Answer

Click here for → OBJECTIVE-I

Click here for → Friction - OBJECTIVE-II

Click here for → EXERCISES (1-10)

Click here for → Exercises (11-20)

Click here for → EXERCISES (21-31)

For more practice on problems on friction solve these- "New Questions on Friction".

---------------------------------------------------------------------------------

CHAPTER- 5 - Newton's Laws of Motion

Click here for → QUESTIONS FOR SHORT ANSWER

Click here for→ Newton's laws of motion - Objective - I

Click here for → Newton's Laws of Motion - Objective -II

Click here for → Newton's Laws of Motion-Exercises(Q. No. 1 to 12)

Click here for→Newton's Laws of Motion,Exercises(Q.No. 13 to 27)

Click here for→Newton's Laws of Motion,Exercises(Q.No. 28 to 42)
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CHAPTER- 4 - The Forces

The Forces-

"Questions for short Answers"

Click here for "The Forces" - OBJECTIVE-I

Click here for "The Forces" - OBJECTIVE-II

Click here for "The Forces" - Exercises

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Sunday, September 20, 2020

H C Verma solutions, ELECTRIC FIELD AND POTENTIAL, OBJECTIVE-I, Chapter-29, Concepts of Physics, Part-II

1. Figure (29-Q2) shows some of the electric field lines corresponding to an electric field. The figure suggests thatFigure for Q-1

(a) EA > EB > EC

(b) EA = EB = EC

(c) EA = EC > EB

(d) EA = EC < EB

Answer: (c).

Explanation: There are an equal number of electric field lines within the same areas at A and C but fewer lines at B.

2. When the separation between two charges is increased the electric potential energy of the charges

(a) increases

(b) decreases

(c) remains the same

(d) may increase or decrease

Answer: (d).

3. If a positive charge is shifted from a low potential region to a high potential region, the electric potential energy

(a) increases

(b) decreases

(c) remains the same

(d) may increase or decrease.

Answer: (a).

Explanation: In shifting a positive charge from low potential energy region to high potential energy region work will be done against the electric force, i.e. the work done by the electric force is negative so the potential energy is positive, i.e. the electric potential energy increases.

4. Two equal positive charges are kept at points A and B. The electric potential at the points between A and B (excluding these points) is studied while moving from A to B. The potential

(a) continuously increases

(b) continuously decreases

(c) increases then decrease

(d) decreases then increase.

Answer: (d).

Explanation: Suppose two positive charges q and q are placed at distnce r from each other. Potential at a point P at a diatance x from A (x<r) due to these charges will be

V = q/4πєₒx + q/4πєₒ(r-x)

=(q/4πєₒ){(r-x+x)/x(r-x)}

=qr/4πєₒx(r-x)

differentiating V with respect to x we get

dV/dx =(qr/4πєₒ)[-1/x²(r-x) +1/x(r-x)²]

={qr/4πєₒx(r-x)}[1/(r-x)-1/x]

=qr(2x-r)/4πєₒx²(r-x)²

At x → 0, dV/dx →Infinity(-ve)

at x =r/2, dV/dx = 0,

at x →r, dV/dx →Infinity(+ve)

So the potential first decreases and after x =r/2 it increases.

(a) A

(b) B

(c) C

(d) D.

Answer: (a).

Explanation: Since the potential decreases at the maximum rate along the electric field, the minimum potential among these four will be minimum at the point on the x-axis i.e. at A.

6. If a body is charged by rubbing it, its weight

(a) remains precisely constant

(b) increases slightly

(c) decreases slightly

(d) may increase slightly or may decrease slightly.

Answer: (d).

Explanation: When a body is charged by rubbing, either it gets some electrons from another body to be negatively charged or loses some electrons to be positively charged. So either its weight may increase slightly or decrease slightly due to the elctron transfers.

7. An electric dipole is placed in a uniform electric field. The net electric force on the dipole

(a) is always zero

(b) depends on the orientation of the dipole

(c) can never be zero

(d) depends on the strength of the dipole.

Answer: (a).

Explanation: In a uniform electric field both ends will experience equal and opposite force (because the ends of a diapole have equal and opposite charge) hence the net force on the diapole will always be zero. (But there will be the torque).

8. Consider the situation of the figure (29-Q3). The work done in taking a point charge from P to A is WA, from P to B is WB and from P to C is WC.

(a) WA <WB < WC

(b) WA > WB > WC

(c) WA = WB =WC

(d) None of these

Figure for Q-8

Answer: (c).

Explanation: The three points A, B and C are at equal distances from q. So the potential at each of the three points will be equal. Thus the work done in bringing a point charge from P to these points will be equal.

9. A point charge q is rotated along a circle in the electric field generated by another point charge Q. The work done by the electric field on the rotating charge in one complete revolution is

(a) zero

(b) positive

(c) negative

(d) zero if the charge Q is at the center and nonzero otherwise.

Answer: (a).

Explanation: The work done by the electric field depends upon the final and initial positions, not on the path followed by the charge. In one complete revolution, the rotating charge comes to the same point hence no work is done.

------------------------------------------------

Click here for all links → kktutor.blogspot.com

For beginners - Vectors & its addition -YouTube

===<<<O>>>===

My Channel on YouTube → SimplePhysics with KK

1. Figure (29-Q2) shows some of the electric field lines corresponding to an electric field. The figure suggests that
Figure for Q-1

(a) E_A > E_B > E_C

(b) E_A = E_B = E_C

(c) E_A = E_C > E_B

(d) E_A = E_C < E_B

8. Consider the situation of the figure (29-Q3). The work done in taking a point charge from P to A is W_A, from P to B is W_B and from P to C is W_C.

(a) W_A <W_B < W_C

(b) W_A > W_B > W_C

(c) W_A = W_B =W_C