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DPP - Daily Practice Problems

Name : Date :
RAVISH CLASSES
Start Time : End Time :

SYLLABUS : Electrostatics-1 (Coulomb's law, electric field, field lines, Gauss's law)
32
Max. Marks : 104 Time : 60 min.
GENERAL INSTRUCTIONS
• The Daily Practice Problem Sheet contains 26 MCQ's. For each question only one option is correct. Darken the correct
circle/ bubble in the Response Grid provided on each page.
• You have to evaluate your Response Grids yourself with the help of solution booklet.
• Each correct answer will get you 4 marks and 1 mark shall be deduced for each incorrect answer. No mark will be given/
deducted if no bubble is filled. Keep a timer in front of you and stop immediately at the end of 60 min.
• The sheet follows a particular syllabus. Do not attempt the sheet before you have completed your preparation for that
syllabus. Refer syllabus sheet in the starting of the book for the syllabus of all the DPP sheets.
• After completing the sheet check your answers with the solution booklet and complete the Result Grid. Finally spend time
to analyse your performance and revise the areas which emerge out as weak in your evaluation.

DIRECTIONS (Q.1-Q.18) : There are 18 multiple choice 1 Q2 1 Q2

(c) 180o , o
(d) 180 ,
questions. Each question has 4 choices (a), (b), (c) and (d), out 4p Î0 2 L2 4p Î0 L2
of which ONLY ONE choice is correct. Q.3 Electric charges of 1mC , -1mC and 2mC are placed in air at
Q.1 A total charge Q is broken in two parts Q1 and Q 2 and they the corners A,B and C respectively of an equilateral triangle
ABC having length of each side 10 cm. The resultant force
are placed at a distance R from each other. The maximum on the charge at C is
force of repulsion between them will occur, when (a) 0.9 N (b) 1.8N (c) 2.7 N (d) 3.6 N
Q Q Q 2Q Q.4 An electron is moving round the nucleus of a hydrogen
(a) Q 2 = , Q1 = Q - (b) Q2 = , Q1 = Q -
R R 4 3 atom in a circular orbit of radius r. The coulomb force
Q 3Q Q Q ur 1
(c) Q 2 = , Q1 = (d) Q1 = , Q2 = F between the two is (here K = )
4 4 2 2 4 p Î0
Q.2 Two small balls each having the charge + Q are suspended e2 e2 r e2 r e2
by insulating threads of length L from a hook. This (a) - K 3 r$ (b) K 3 r (c) - K 3 r (d) K 2 r$
r r r r
arrangement is taken in space where there is no
gravitational effect, then the angle between the two Q.5 Equal charges q are 2placed at the four corners A2, B, C , D of a
o 1 Q 1 Q
suspensions and the tension in each thread will be (a) 180
square ,
of length a . The
2 magnitude ofothe
(b) 90 , force on the charge
4 p Î0 (2 L ) 4p Î0 L
2

RESPONSE GRID 1. 2. 3. 4.
Space for Rough Work
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at B will be of –3Q, it is
3q 2
q 2 (a) –E (b) E/3 (c) –3E (d) –E/3
(a) (b) Q.12 Charges q, 2q, 3q and 4q are placed at the corners A, B, C
4p Î0 a 2 p Î0 a 2
æ 1+ 2 2 ö q2
and D of a square as shown in the following figure. The
æ 1 ö q2
(c) çè ÷ (d) ç 2 + ÷ø direction of electric field at the centre of the square is
2 ø 4p Î0 a 2 è
Q.6 The charges on two spheres are +7mC and –5mC
RAVISH
2 4 p Î0 a 2
CLASSES
parallel to side.
D C
(a) AB 4q 3q
respectively. They experience a force F. If each of them is
given an additional charge of –2mC, the new force of (b) CB
attraction will be O
(c) BD q 2q
(a) F (b) F/2 (c) F / 3 (d) 2F (d) AC A B
Q.7 Electric lines of force about negative point charge are Q.13 Three infinitely long non-conducting charge sheets are
(a) Circular, anticlockwise (b) Circular, clockwise placed as shown in figure. The electric field at point P is
(c) Radial, inward (d) Radial, outward 2s $
Q.8 Figure shows the electric lines of force emerging from a (a) k
e0 Z
charged body. If the electric field at A and B are E A and
2s $
(b) – k Z = 3a
EB respectively and if the distance between A and B is r then e0
P
(a) E A > EB 4s $ -2 s Z=a
(c) k
(b) E A < E B e0 x

E A B 4s $ Z=–a
(c) E A = B
r (d) – k
r e0
EB Q.14 Gauss's law is true only if force due to a charge varies as
(d) E A = 2 (a) r–1 (b) r–2 (c) r–3 (d) r–4
r
Q.9 The magnitude of electric field intensity E is such that, Q.15 The electric intensity due to an infinite cylinder of radius
an electron placed in it would experience an electrical R and having charge q per unit length at a distance r(r > R)
force equal to its weight is given by from its axis is
e e2
(a) Directly proprotional to r2
mg
(a) mge (b) (c) mg (d) 2 g (b) Directly proprotional to r3
e m
(c) Inversely proprotional to r
Q.10 A charge particle is free to move in an electric field. It
(d) Inversely proprotional to r2
will travel
Q.16 A sphere of radius R has a uniform distribution of electric
(a) Always along a line of force
charge in its volume. At a distance x from its centre, for
(b) Along a line of force, if its initial velocity is zero
x < R, the eletric field is directly proportional to
(c) Along a line of force, if it has some initial velocity in
the direction of an acute angle with the line of force 1 1
(d) None of the above (a) 2 (b) (c) x (d) x2
x x
Q.11 Two point charges Q and –3Q are placed at some distance apart.
Q.17 A charged ball B hangs from a silk thread S, which makes an
If the electric field at the location of Q is E then at the locality
angle q with a large charged conducting sheet P, as shown

5. 6. 7. 8. 9.
RESPONSE
10. 11. 12. 13. 14.
GRID
15. 16.

Space for Rough Work

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DPP/ P 32 3
in the figure. The surface charge density s of the sheet is (3) If a uniform downward electric field is switched on, T will
proportional to increase
+ (4) If a uniform downward electric field is switched on,
(a) sin q +
P + T will decrease
(b) tan q + q
+ DIRECTIONS (Q.21-Q.23) : Read the passage given below
S
(c) cos q
RAVISH
+
+ CLASSES
and answer the questions that follows :
(d) cot q B
Q.18 A charge q is placed at the centre of a cube. Then the flux A sphere of radius R contains charge density r (r ) = A( R - r ),
passing through one face of cube will be for 0 < r < R. The total electric charge inside the sphere is Q.
q q q q
(a) (b) (c) (d)
Î0 2 Î0 4 Î0 6 Î0 Q.21 The value of A in terms of Q and R is
DIRECTIONS (Q.19-Q.20) : In the following questions, 2Q 2 3Q 3Q 2 3Q
(a) (b) (c) (d)
more than one of the answers given are correct. Select pR 4
pR 4
pR 3 pR
the correct answers and mark it according to the following Q.22 The electric field inside the sphere is
codes:
12Q2 é 1 æ r ö 1 æ r ö ù
2
3Q é 1 æ r ö 1 æ r ö ù
2
Codes : (a) ê ç ÷ - ç ÷ ú (b) ê ç ÷- ç ÷ ú
Î0 R 2 êë 3 è R ø 4 è R ø úû R3 êë 3 è R ø 4 è R ø úû
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
120Q é 1 æ r ö 1 æ r ö ù 12 é 1 æ r ö 1 æ r ö ù
2 2
(c) 2 and 4 are correct (d) 1 and 3 are correct
(c) ê -
2 4 çè R ÷ø 3 çè R ÷ø
ú (d) 2 ê ç ÷ - ç ÷ ú
Q.19 A solid sphere S1 is connected to a charge reservoir through 5 Î0 R êë úû R Q êë 3 è R ø 4 è R ø úû
a heater H as shown in figure.
Q.23 The electric field outside the sphere is æç k =
S2 1 ö
S1
H è 4 p Î0 ÷ø
Solid Solid
Heater
sphere sphere kQ kQ kQ kQ 2
(a) (b) (c) (d)
Flux through a closed spherical surface around S1 is given r r 2
r 3
r2
by f = a t2 where a is a constant and t is time in seconds.
If resistance of heater is R then select correct statements DIRECTIONS (Q. 24-Q.26) : Each of these questions
(1) Power consumed by heater will be 4a2e02 Rt2. contains two statements: Statement-1 (Assertion) and
(2) Electric flux through a closed spherical surface around Statement-2 (Reason). Each of these questions has four
S2 will be – a t2. alternative choices, only one of which is the correct answer.
(3) Rate of change of electric flux through a closed You have to select the correct choice.
spherical surface around S2 will be –2a t (a) Statement-1 is True, Statement-2 is True; Statement-2 is a
(4) All of the above are correct correct explanation for Statement-1.
Q.20 A simple pendulum has a time period T. The bob is now (b) Statement-1 is True, Statement-2 is True; Statement-2 is
given some positive charge – NOT a correct explanation for Statement-1.
(1) If some positive charge is placed at the point of (c) Statement -1 is False, Statement-2 is True.
suspension, T will increases (d) Statement -1 is True, Statement-2 is False.
(2) If some positive charge is placed at the point of
suspension, T will not change Q.24 Statement-1 : Electric lines of force cross each other.
Statement-2 : Electric field at a point superimpose to give

RESPONSE 17. 18. 19. 20. 21.

GRID 22. 23.

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one resultant electric field. Q.26 Statement-1 : Direction of electric field at a point signifies
Q.25 Statement-1 : A point charge is brought in an electric field. The direction of force experienced by a point charge placed at
field at a nearby point will increase, whatever be the nature of that point.
the charge. Statement-2 : Electric field is a vector quantity.
Statement-2 : The electric field is dependent on the nature of
charge. RAVISH CLASSES
RESPONSE GRID 24. 25. 26.

DAILY PRA CTICE PROBLEM SHEET 32 - PHYSICS

Total Questions 26 Total Marks 104
Attempted Correct
Incorrect N et Score
Cut-off Score 25 Qualifying Score 40
Success Gap = Net Score – Qualifying Score
Net Score = (Correct × 4) – (Incorrect × 1)

Space for Rough Work