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CBSE Questions for Class 12 Medical Physics Electrostatic Potential And Capacitance Quiz 14 - MCQExams.com

The equivalent capacitance between the points A and B in the given diagram is:
1119083_567014c820bf49a5ad3c5009f97e92dc.png
  • 8μF
  • 6μF
  • 83μF
  • 38μF
A non conducting semicircular disc (as shown in figure) has a uniform surface charge density σ. The electric potential at the centre of the disc:-
1115270_e1d6a8d29f7640d08f9689dbd8a7cf54.png
  • σ ιn(b/a)2π ε0 (ba)
  • σ(ba)2 ε0
  • σ(ba)4 ε0
  • σ(ba)4π ε0
A sliding rod AB of resistance R is shown in the figure. Here magnetic field B is constant and is Out of the paper. Parallel wires have no resistance and the rod is moving with Constant velocity v. The current in the sliding rod AB in the function of t, when switch S is closed at time t = 0 is
942497_9c0413e3e8bc45be814b8b7575bc1d11.png
  • (vBdR)et/C
  • (vBdR)et/RC
  • (vBdR)eRtC
  • (vBdR)et/RC
In a quark model of elemetary particles, a neutron is made of one up quark of charge 23e and two down quark of charges (13e). If they have a triangle configuration with side length of the order of 1015m. The electrostatic potential energy of neutron in MeV is
  • 7.68
  • 5.21
  • .048
  • 9.34
The gravitational field strength E and gravitational potential V are related as E=(Vxˆi+Vyˆj+Vzˆk)
In the figure, transversal lines represent equipotential surfaces. A particle of mass m is released from rest at the origin. The gravitational unit of potential, 1¯V=1 cm2/s2.
X-component of the velocity of the particle at the point (4cm,4cm) is
1013885_a8cc92d0bfe14fca9dca1252d62ce791.jpg
  • $$4\ cm/s$
  • 2 cm/s
  • 22cms
  • 1 cm/s
A parallel plate air capacitor is connected to a battery. The quantities charge, voltage, electric field and energy associated with this capacitor are given by Q0,V0,E0, and U0 respectively. A dielectric slab is now introduced to fill the space between the plates with the battery still in connection. The corresponding quantities now given by Q,V,E and U are related to the previous one as
  • Q>Q0
  • V>V0
  • E>E0
  • U>U0
A parallel plate capacitor of plate area A and plate separation d is charged to potential difference V and then the battery is disconnected. A slab of dielectric constant K is then inserted between the plate of the capacitor so as to fill the space between the plates. If Q,E and W denote respectively, the magnitude of charge on each plate, the electric field between the plates (after the slab inserted), and work done on the system, in question, in the process of inserting the slab, then
  • Q=ε0AVd
  • Q=ε0KAVd
  • E=VKd
  • W=ε0AV22d[11K]
Two point charges placed 3m apart, have a combined charge 20 μC. Find the two charges if they repeleach other with a force 0.075 N.
  • 25μC, -5μC
  • 30 μC, 10μC
  • 30μC, 50μC
  • 15 μC, 5μC
A capacitor of 2F is charged as shown in the diagram. When the switch S is tuned to position 2, the percentage of its stored energy dissipated is :
1026361_65016fc38bb3483c97125749ac59e07d.png
  • 80 %
  • 0 %
  • 20 %
  • 75 %
The gravitational field strength E and gravitational potential V are related as E=(Vxˆi+Vyˆj+Vzˆk)
In the figure, transversal lines represent equipotential surfaces. A particle of mass m is released from rest at the origin. The gravitational unit of potential, 1¯V=1 cm2/s2.
Speed of the particle (v)(y is in cm v is in cm/s) as function of its y-co-ordinate is
1013886_26378f80e0214e4cbc577b8d8ee065ae.png
  • v=2y
  • v=2.y
  • v=2y
  • v=2y+4y2+2y2
One plate of a parallel plate capacitor is suspended from a beam of a physical balance as shown in figure. The area of each plate is 625 cm2 and the distance between these plates is 5 mm. If an additional mass 0.04 gm is placed in the other pan of the balance, then the potential difference required between the plates to keep it in equilibrium will be:
1065915_07a84453654e4b7bb8321ad96eade01e.png
  • 150 V
  • 188 V
  • 225 V
  • 310 V
The diagram shows a small bead of mass m carrying charge q. The bead can freely move on the smooth fixed ring placed on a smooth horizontal plan. In the same plane a charge +Q has also been fixed as shown. The potential at the point P due to +Q is V. The velocity with which the bead should projected from the point P so that it can complete a circle should be greater than
1027137_b0383e9bbf7b4f14ae2838cc20e295c1.png
  • 6qVm
  • qVm
  • 3qVm
  • none
A uniformly charged solid sphere of radius R has potential V0 (measured with respect to ) on its surface. For this sphere the equipotential surfaces with potentials 3V02,5V04,3V04 and V04 have radius R1,R2,R3, and R4 respectively. Then
  • R1=0 and R2>(R4 R3)
  • R10 and (R2 R1)>(R4 R3)
  • R1=0 and R2<(R4 R3)
  • 2R<R4
A dipole of 2μC charges each, consists of the positive charge at the point P(1,1) and the negative charge is placed at the point Q(1,1). The work done in displacing a charge of +1μC from point A(3,3) to B(4,4) is:
  • 1.6×1019J
  • 3.2×1019J
  • zero
  • 4.8eV
Two equal charges q are placed at a distance of 2a and a third charge 2q is placed at the midpoint. The potential energy of the system is
  • q28πε0a
  • 6q28πε0a
  • 7q28πε0a
  • 9q28πε0a
The variation of potential with distance R from a fixed point is as shown below. A charge q is put at R=3 m and released. The charge will 
1033045_81fb2872e3bd46e899e2f83cce9b9400.png
  • Move away from origin
  • Move towards the origin
  • Not move
  • Trace a circular path
The electric potential at a point in free space due to a charge Q coulomb is Q×1011V. The electric field at that point is 
  • 4πε0Q×1022V/m
  • 127πε0Q×1020V/m
  • 4πε0Q×1020V/m
  • 12πε0Q×1022V/m
The distance between electric charges 1μC and 3μC is 8m. What is the electric potential at a point on the line joining them where the electric field is zero? (k=9×109 SI)
  • 9×102
  • 9×103
  • 9×104
  • 9×105
A dielectric slab of thickness d inserted in a parallel plate capacitor whose negative plate is at x=0 and   positive plate is at x=3d.  The slab is equidistant from the plates. The capacitor is given some charge .As x goes from 0 to 3d:
  • The magnitude of the elecrtric field remains the same.
  • The direction of the electric field remains the same.
  • The electric potential increases continuously.
  • The electric potential increase at firstthen decreases and again increases.
The capacity of a parallel plate capacitor formed by the plates of same are A is 0.02μF with air as dielectric. Now one plate is replaced by a plate of area 2A and dielectric (K = 2) is introduced between the plates, the capacity is :
  • 0.04 μF
  • 0.08μF
  • 9.91 μF
  • 2 μF
4 μF and 6 μF capacitors are joined in series and 500 v are applied between the outer plates of the system. What is the charge on each plate ?
  • 12×103 C
  • 60×103 C
  • 50×103 C
  • 20×103 C
Select the correct statements:
  • The electric lines of force are always closed curves.
  • Electric line of forced is parallel to equipotential surface
  • Electric line of force is perpendicular to equipotential surface.
  • Electric line of force is always the path of a positively charged particle.
Three long concentric cylindrical shells have radii R, 2R and 22R. Inner and outer shells are connected to each other. The capacitance across middle and inner shells per unit length is:
  • 13ϵ0ln2
  • 6πϵ0ln2
  • πϵ02ln2
  • None
The capacitance of a capacitor is 10F. The potential difference on it is 50V. If the distance between its plate is halved, What will be the potential difference now?
  • 100V
  • 50V
  • 25V
  • 75V
Four condenser each of capacity 4μF are connected as shown in figure VpVq=15 volts. The energy stored in the system is 
1044004_204a0377a24f4669b820253058f5b808.png
  • 2400 ergs
  • 1800 ergs
  • 3600 ergs
  • 5400 ergs
Two condensers of capacity 0.3μF and 0.6μF respectively are connected in series. The combination is connected across a potential of 6 volts. The ratio of energies stored by the condensers will be:
  • 12
  • 2
  • 14
  • 4
Two materials of dielectric constants k1andk2 are introduced to fill the space between the two parallel plates of a capacitor as shown in the figure. The capacitance of the capacitor is : 
1110672_dc750a7667cc48519e3fe7fc1c8bfb4d.png
  • A0(k1+k2)2d
  • 2A0d(k1k2k1+k2)
  • A0d(k1k2k1+k2)
  • A0(k1+k2)2dk1k2
A parallel plate capacitor is made of two dielectric blocks in series. One of the blocks has thickness d1 and dielectric constant k1 and the other has thickness d2 and dielectric constant k2 as shown in fig. This arrangement can be thought as a dielectric slab of thickness d=d1+d2 and effective dielectric constant k. The k is then :
1077587_5d2711f63bad4e33bd66eacedf160a2e.png
  • k1d1+k2d2d1+d2
  • k1d1+k2d2k1+k2
  • k1k2(d1+d2)k1d2+k2d1
  • 2k1k2k1+k2
Electrical potential in an electric field is given by V=K/r (K being constant). If the position vector r=2ˆi+3ˆj+6ˆk , then the electric field will be 
  • 2ˆi+3ˆj+6ˆk243K
  • 2ˆi+3ˆj+6ˆk343K
  • 3ˆi+2ˆj+6ˆk243K
  • 3ˆi+2ˆj+6ˆk343K
Capacitance C1=2C2=2C3 and potential difference across C1,C2 and C3 are V1,V2 and V3 respectively then:
1103108_4c4e28ef1a1c427d9862cca4c20b32bc.png
  • V1=V2=V3
  • V1=2V2=2V3
  • 2V1=V2=V3
  • 2V1=2V2=V3
A parallel-plate capacitor of plate area A and plate separation d is charged to a potential difference and then the battery is disconnected. A slab of dielectric constant K is then inserted between the plates of the capacitor so as to fill the whole space between the plates. Find the work done on the system the process of inserting the slab.
  • ε0AV22d(11K)
  • ε0AV2d(1K1)
  • ε0AV22d(1K+1)
  • ε0AV2d(1K+1)
In the figure show the potential difference between hollow spheres A and B is:-
1091638_c04bd368dc964abb87290fa68a005a84.JPG
  • zero
  • q16πε0R
  • q16πε0R
  • q24πε0R
Consider a capacitor-charging circuit. Let Q1 be the charge given to the capacitor in a time interval of 10ms and Q2 be the charge given in the next time interval of 10ms. Let 10μC charge be deposited in a time interval t1 and the next 10μC charge is deposited in the next time interval t2.
  • Q1>Q2,t1>t2
  • Q1>Q2,t1<t2
  • Q1<Q2,t1>t2
  • Q1<Q2,t1<t2
The potential difference between points A and D in the given circuit is:-
1121036_925ce5f59c2542a7af8bf486e821266f.PNG
  • 23V
  • 89V
  • 43V
  • 2V
Two long straight wires equal cross- sectional radii a are located parallel to each other in air. The distance between their axes equal b. Find the mutual capacitance of the wire per unit length under the condition b>>a.
  • C=πε0ln(b/a)
  • C=πε0ln(a/b)
  • C=π/ε0In(b/a)
  • C=πε0ln(ba)
what is the series combination of condenses and 1c=1c1+1c2+1c3 farad
  • True
  • False
A point charge +Q is located at out side point, at a distance of r from the centre of an uncharged conducting sphere of radius R. Find the electric field and electric potential at the centre of the sphere due to induced charges on the sphere ?
  • 14πϵ0QR2 and Zero
  • Zero and 14πϵ0QR
  • 14πϵ0QR2 and 14πϵ0QR
  • Zero and Zero
The potential at a point x (measured in μm ) due to some charges situated on the x -axis is given by V(x)=20(x24) volt. The electric field E at x=4μm is given by
  • (109)Vμm1 and in the +ve x direction
  • (53)Vμm1 and in the -ve x direction
  • (53)Vμm1 and in the +ve x direction
  • (109)Vμm1 and in the -ve x direction
A dielectric slab of thickness d is inserted in a parallel plate capacitor whose negative plate is at x = 0 and positive plate is at x = 3d. The slab is equidistant from the plates. The slab is equidistant from the plates. The capacitor is given some charge. As x goes  from 0 to 3 d:  
  • The magnitude of the electric field remains the same
  • The direction of the electric field remains the same
  • the electric potential increase continuously.
  • The electric potential increase at first, then decreases and again increase
The electric potential in a certain region is expressed by V=6x8xy28y+6yz4z2 volts. The magnitude of the force acting on a charge of 2C sityuated at the origin wil be:-
  • 2N
  • 6N
  • 8N
  • 20N
Two parallel plates have equal and opposite charge. When the space between them is evacuated, the electric field between the plates is 2× 105 V/m. When the space is filled with dielectric, the electric field becomes 1× 105 V/m. The dielectric constant of a dielectric material is:
  • 1/2
  • 1
  • 2
  • 3
A capacitor 1 mF withstands a maximum voltage of 6KV while another capacitor 2 mF withstands a maximum voltage of 4 KV. If the capacitors are connected in series, the system will withstand a maximum voltage of (MNR)
  • 2 KV
  • 4 KV
  • 6 KV
  • 9 KV
Three point charges of 1C,2C and 3C are placed at the corners of an equilateral triangle of side 100 cm. The work done to move these charges to the corners of a similar equilateral triangle of side 50 cm, will be
  • 9.9×1010J
  • 9.9×109J
  • 5.2×1010J
  • 5.9×109J
In the figure a potential of +1200 V is given to point A and point B is earthed,what is the potential at the point P
1212347_a4f4e177c47b4a6c82f531568a60660f.png
  • 100 V
  • 200 V
  • 400 V
  • 600 V
A straight conductor of length l carrying a current t, is bent in the form of a semi-circle, The magnetic field in tesla at the center of the semi-circle is.
  • π2il×107
  • iπl×107
  • iπl2×107
  • π2l×107
  • None of the above.
A parallel plate capacitor has plate area A and separation  d. It is charged to a potential difference V0. The charging battery is disconnected and the plates are pulled apart to three times the initial separation. The work required to separate the plates is:
  • 3ϵ0AV20d
  • ϵ0AV202d
  • ϵ0AV203d
  • ϵ0AV20d
A thin metal plate P is inserted half way between the plates of a parallel plate capacitor of capacitance C in such a way that it is parallel to the two plates. The capacitance now becomes 
  • C
  • C/2
  • 4C
  • None of these
In given circuit when switch S has been closed then charge on capacitor A & B respectively

1202068_1becc4ff245849a1affaa348aa596399.png
  • 3 q,6 q
  • 6 q,3 q
  • 4.5 q,4.5 q
  • 5,4 q,4 q
Two condemners of capacity 0.3μ F and 0.6μ F respectively are connected in series. The combination is connected across a potential  of 6 volts. The ratio  of energies stared by the condensers will be
  • 12
  • 2
  • 14
  • 4
A parallel plate capacitor consist of two circular plates each of radius 2 cm, separated by a distance of 0.1 mm. If voltage across the plates is varying at the rate of 5×1013Vs1 , then the value of displacement current is:
  • 5.50A 
  • 5.56×102A
  • 5.56×103A
  • 2.28×104A
0:0:1


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Practice Class 12 Medical Physics Quiz Questions and Answers