Q.1
An air capacitor of capacity C=10µF is connected to a constant voltage battery of 12V. Now, the space is filled with a liquid of dielectric constantThe charge that flow now from battery to the capacitor is [ MPPMT 1997]
  • a) 120 µC
  • b) 600 µC
  • c)480 µC
  • d)24 µC
Q.2
An automobile spring extends 0.2m from 5000N load. The ratio of potential energy stored in this spring when it has been compressed by 0.2m to the potential energy stored in 10µF capacitor at a potential difference of 10,000V is [ B>HU 1996]
  • a)2
  • b)1/2
  • c)1
  • d)1/4
Q.3
A parallel plate capacitor C is connected to a battery and is charged to a potential difference V. Another capacitor of capacitance 2C is connected to another battery and is charged to potential difference 2V. The charging batteries are now disconnected and the capacitors are connected in parallel to each other in such a way that the positive terminal of one is connected to the negative terminal of the other. The final energy of the configuration is [ IIT 1995]
  • a) zero
  • b) 25CV2 / 6
  • c) 3CV2 / 2
  • d) 9CV2 / 2
Q.4
Two point charges placed at a cetrain distance r in air exerts a force of F on each other. Then the distance r' at which these charges will experience the same force in a medium of dlelectric constant K is
  • a)r
  • b) r/K
  • c)r/√K
  • d)r√K
Q.5
Charges +q, -4q and +2q are arranged at the corners of an equilaterial triangle of side 0.15m. If q=1µC, their mutual potential energy is
  • a) 0.4 J
  • b) 0.5 J
  • c)0.6 J
  • d)0.8 J
Q.6
A hollow sphere of copper is having a uniform charge density of 0.5µC/mIts radius is 0.1 m. ThE potential at the centre of the sphere is
  • a) zero
  • b) 1800π volts
  • c)180π volts
  • d)4.5 kV
Q.7
The force between two short electric dipoles separated by a distance r varies as
  • a) r2
  • b) r4
  • c)r-2
  • d)r-4
Q.8
Two thin concentric hollow conducting spheres of radii R1 and R2 bears changes Q1 and Q2 respectively. If R1 > R2 then the potentil at point distance r such that : ( R1 > r > R2)
  • a)
    ch-13_qn-229choice_img_no1.png
  • b)
    ch-13_qn-229choice_img_no2.png
  • c)
    ch-13_qn-229choice_img_no3.png
  • d)
    ch-13_qn-229choice_img_no4.png
Q.9
Two small spheres carry charge of +3 nC and -12 nC respectively. The charges are distance d apart. The force they exert on one another is FThe spheres are made to touch one another and then separated to distance d apart. The force they exerts on one another is now F2 . Then F1 /F2
  • a) 1
  • b) 2
  • c)1/2
  • d)16:9
Q.10
A cylinder of radius R and length L, is placed in the region of uniform electric field E as shown in figure. The electric flux linked with cylinder is
ch-13_que_no-231_img_no1.png
  • a) R/L
  • b) R2/L
  • c)zero
  • d)infinity
Q.11
Equal and opposite sharges q are placed at point A and B as shown in figure P1 and P2 are equidistant from O. The ratio of P1 . P2 is
ch-13_que_no-232_img_no1.png
  • a) 1
  • b) b/a
  • c) zero
  • d) infinity
Q.12
A is a spherical conductor placed concentrically inside a hollow spherical conductor B, +Q charge is given to A and B is earthed. The electric field intensity is not zero
ch-13_que_no-233_img_no1.png
  • a)inside A
  • b) otside B
  • c)on the surcae of B
  • d)between A and B
Q.13
An insulated sphere of radius R has a uniform charge density λ. The electric field at point P inside the sphere and at distance r from the centre is
ch-13_que_no-234_img_no1.png
  • a) zero
  • b) Rλ / 3εo
  • c)rλ / 3εo
  • d)(2/3) (rλ / εo)
Q.14
A ball of mass 600mg and having charge 5 µC is suspended by a thread in between two parallel plates as shown in figure. The distance between the two plates is 10cm and the potential difference between them is 30V. The tention in the string is
ch-13_que_no-235_img_no1.png
  • a)0.667 m
  • b) 0.5 m
  • c)0.4 m
  • d)0.6 m
Q.15
The work done in carrying a charge of 5µC from point A and B is 8mJ. The difference of potential between A and B is
  • a) 160 V
  • b) 16 V
  • c) 1.6kV
  • d) 16 kV
Q.16
the uncharged matallic sphere A suspended as shown in figure is given a push so that it moves towards +ve plate. Which one of the following statement is correct?
ch-13_que_no-237_img_no1.png
  • a)A touches +ve plate and remain in contact with it
  • b) A touches +ve plate and then moves towards -ve plate and remains in contact with it
  • c)A moves to and fro between the two plates with a constant time period
  • d)A moves to and fro between the two plates with an increasing time-period
Q.17
the number of electric lines of force crossing the surface of an arbitrary curve of surface area S and enclosing a charge q is
  • a) εo
  • b)qεoS
  • c)q/εo
  • d)qV/εo
Q.18
Charges of 2µC and -3µC are placed at two point A and B distance 1 m as shown in figure. The distance of the point from A, where net potential is zero, is
ch-13_que_no-240_img_no1.png
  • a) 0.667 m
  • b) 0.5 m
  • c) 0.4 m
  • d) 0.6 m
Q.19
Electric potential V at some point in space is zero. This means
  • a) electric field at that point is necessarily zero
  • b) electric field at that point is necessarily non-zero
  • c)electric field at that point may or may not be non-zero
  • d)none of above
Q.20
A charged conductor B is kept inside another hollow uncharged conductor A. B is in contact with A. What will be the effect of charge on B
  • a) Total charge on B is transferred to A and comes on the outer surface of A
  • b) Total charge on B is transferred to A and remains on inner surface of A
  • c)Opposite charge is induced on the outer surface of A
  • d)Charge on B is not transferred to A at all.
Q.21
Charges are placed at the corners of a square of side a as shown in figure. The charge A is in equilibrium. The ratio q1 / q2
ch-13_que_no-244_img_no1.png
  • a) 1
  • b) √2
  • c) 1/√2
  • d) 2√2
Q.22
Mechanical force per unit area of a charged conductor having surface charge density σ is proportional to
  • a)1 / σ2
  • b) σ2
  • c)σ
  • d)√σ
Q.23
You are travelling in a car during a thunder storm. In order to protect yourself from lightning would you prefer to
  • a) remain in the car
  • b) take shelter under a tree
  • c)get out and lie flat on the ground
  • d)touch the nearest electric pole
Q.24
Two point charges placed at a distance of 20cm in air repel each other with certain force. When a dielectic slab of thickness 8cm and dielectric constant K is intoduced between these point charges, the force of interaction becomes half of its previous value. Then K is approximately
  • a) 2
  • b) 4
  • c) √2
  • d) 1
Q.25
Capacitor C, 2C, 4C, ...∞ all are connected in parallel, their effective capacitance will be
  • a)C
  • b) C/2
  • c) ∞
  • d)0
Q.26
A metal sphere is held fixed on a smooth horizontal insulated plate and another small metal sphere is placed at some distance away. If the fixed sphere is given a charge, then
  • a) the another sphere will be attracted towards first
  • b) the another sphere will be repelled by the first
  • c)there will be no effect at all
  • d)the another sphere will move towards the first sphere and after contact it will be repelled
Q.27
In the following diagram a particle with small charge -q is free to move up or down but not sideways near a larger fixed charge Q. The small charge is in equilibrium because in the positions shown shown the electrical upward force is equal to the weight of the particle. Which statement is true
ch-13_que_no-251_img_no1.png
  • a)In fiure A, -q is in stable equilibrium
  • b) In figure A , -q is in neutral equilibrium
  • c)in figure B , -q is in stable equilibrium
  • d)neither in figure A nor in B, q is in stable equilibrium
Q.28
In the electric field of a point charge q, a certain charge is carried from point A to B, C, D, and E. Then work done :
ch-13_que_no-252_img_no1.png
  • a) is least along the path AB
  • b) is least along the path AD
  • c) is zero along any one of the path AB, AC, AD, AE
  • d) is least along AE
Q.29
The variation of potential with distance R from a fixed point is as shown below. The electric field at R=5m is
ch-13_que_no-253_img_no1.png
  • a)2.5 volts/m
  • b) -2.5 volts/m
  • c)2/5 volts/m
  • d)-2/5 volts/m
Q.30
A table tennis ball, which has been covered with a conducting paint is suspended by a silk thread so that it hangs between two metal plates. One plate is earthed, while the other plate is attached to the heigh voltage generator the ball
  • a) is attracted to the high voltage plates and stay there
  • b) hangs without moving
  • c)swings backward and forward hitting each plate in turn
  • d)is repelled by the earthed plate and stays there
Q.31
A small circular ring has a uniform charge distribution. On a far-off axial point distant x from the centre of the ring, the electric field is proportional to
  • a) x-1
  • b) x-3/2
  • c)x-2
  • d)x5/4
Q.32
In figure A is a point on the axis of an electric dipole. The electric field at the location of A is E, If distance of of point A is doubled from O, the field will be ( assume x > a)
ch-13_que_no-256_img_no1.png
  • a) E/4
  • b) E/8
  • c) E/2
  • d) E
Q.33
Two insulated charged sphere of radii 20cm and 25cm respectively and having an equal charge Q are connected by a copper wire and then they are separated
  • a)Both the spheres will have the same charge Q
  • b) Charge on the 20cm sphere will be greater than that on the 25cm sphere
  • c) Charge on the 25cm sphere will be greater than that on the 20cm sphere
  • d)Charge on each sphere will be 2Q
Q.34
Six identical capacitors are joined in parallel, charged to a potential difference of 10V, separated and then connected in series. Then the potential difference between the free plates is
  • a) 10 V
  • b) 30 V
  • c)60 V
  • d)10/6 V
Q.35
A parallel plate capacitor is made by taking n equally spaced plates connected alternate. If the capacitance between ant two successive plates is C, then the capacitance of equivalent system is
  • a) C
  • b) nC
  • c)(n-1)C
  • d)(n+1)C
Q.36
Two spherical conductors A1 and A2 of radii r1 and r2 ( r2 > r1 ) are placed concentrically in air. A1 is given a charge +Q while A2 is earthed. Then the equivalent capacitance of the system is
ch-13_que_no-260_img_no1.png
  • a)
    ch-13_qn-260choice_img_no1.png
  • b)
    ch-13_qn-260choice_img_no2.png
  • c) 4πεor2
  • d) 4πεor1
Q.37
A charged conductor of radius R is connected momentarily to another uncharged spherical conductor of radius r by means of thin conducting wire, then the ratio of the surface charge density of the first to the second conductor is
  • b) R/r
  • c)r/R
  • d)1/1
  • a)R2 / r²
Q.38
A parallel plate air capacitor has a capacitance of 100µµF. The plates are at a distance d apart. A slab of thickness (t < d) and dielectric constant 5 is introduced between the parallel plates. Then the capacitance can be
  • a) 50 µµF
  • b) 100 µµF
  • c)200 µµF
  • d)500 µµF
Q.39
A parallel plate capacitor has circular plates of 10 cms radius separated by an air gap of 1mm. It is charged by connecting the plates to a 100V battery. Then the change in energy stored in the capacitor when the plates are moved to a distance of 1cm. When the plates are maintained in connection with battery is
  • a) loss of 12.5 erg
  • b) gain of 12.5 ergs
  • c)gain of 125 ergs
  • d)loss of 125 ergs
Q.40
A foil of aluminum of negligible thickness is inserted in between the space of a parallel plate condenser. If the foil is electrically insulated, the capacity of the condenser will
  • a) increase
  • b) decrease
  • c) remain unchanged
  • d) become zero
Q.41
A capacitor C1=4µF is connected in series with another capacitor C2=1µF. The combination is connected across a d.c. source of voltage 200 V. The ratio of potential across C2 and C1 is
  • a)1:4
  • b) 4:1
  • c)1:2
  • d)2:1
Q.42
A parallel plate capacitor has a capacity C. The separation between plates is doubled and a dielectric medium is inserted between plates. The new capacity is 3C. The dielectric constant of medium is
  • a) 1.5
  • b) 3.0
  • c)6.0
  • d)12.0
Q.43
ABC is an equilateral triangle of side 1m. Charges are placed at its corners as shown in figure. O is the mid point of side BC. The potential at point is
ch-13_que_no-267_img_no1.png
  • a)2.7×103 V
  • b) 1.52×105 V
  • c)1.3×103 V
  • d)-1.52×105 V
Q.44
A charge particle of charge qo is moved around a charge +q along the circular path from A to B . the work done is :
ch-13_que_no-268_img_no1.png
  • a)
    ch-13_qn-268choice_img_no1.png
  • b)
    ch-13_qn-268choice_img_no2.png
  • c)
    ch-13_qn-268choice_img_no3.png
  • d)zero
Q.45
two balls with equal charges are in vessel with ice at -10°C at a distance of 25cm from each other. On forming water at 0°C, the balls are brought nearer to 5cm from the interaction between them to be same. If the dielectric constant of water at 0°C is 80, the dielectric constant of ice at -10°C is
  • a) 40
  • b) 3.2
  • c)20
  • d)6.4
Q.46
A free proton and a free α-particle initially at a separation of 1Å are released, the kinetic energy of proton and that of α particle when at infinite distance, bears the ratio
  • a) 1 :1
  • b) 1:2
  • c) 14:4
  • d) 4:1
Q.47
In the given figure the resultant capacity will be
ch-13_que_no-498_img_no1.png
  • a) n ( n+1)C
  • b) n (n²+1)C
  • c)nC / (n² + 1)
  • d)n2C /(n² + 1)
Q.48
A charge +q is carried from a point A(r,135°) to point B(r, 45°) following a path which is quadrant of circle of radius r. If the dipole moment is P. the ork done by the external agent is
ch-13_que_no-271_img_no1.png
  • a)zero
    ch-13_qn-271choice_img_no2.png
  • b)
    ch-13_qn-271choice_img_no3.png
  • c)
    ch-13_qn-271choice_img_no4.png
  • d)
Q.49
A metallic plate of thickness t and face area of one side A is inserted between the plates of parallel plate air capacitor with a separation d and face area A. Then the equivalent capacitance is
  • a) εoA/d
  • b) εoA/ (d×A)
  • c)εoA/ (d-t)
  • d)εoA/ (d+t)
Q.50
A parallel plate capacitor is charged and then isolated. What is the effect of increasing the plate separation
  • a) Charge remains constant, Potential remains constant, Capacitance decreases
  • b) Charge increases, Potential increases , Capacitance decreases
  • c)Charge remains constant, Potential decreases, Capacitance increases
  • d)Charge remains constant, Potential remains increases, Capacitance decreases
0 h : 0 m : 1 s