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CBSE Questions for Class 12 Medical Physics Electrostatic Potential And Capacitance Quiz 10 - MCQExams.com

Two points charges 4μC and 2μC are separated by a distance of 1 m in air. At what point in between the charges and on the line joining the charges, is the electric potential zero? 
  • In the middle of the two charges
  • 1/3m from 4μC
  • 1/3m from 2μC
  • Nowhere the potential is zero
In a parallel plate capacitor, the region between the plates is filled by a delectric slab. The capacitor is connected to a cell and the slab is taken out.    
  • Some charge is drawn from the cell
  • Some charge is returned to the cell
  • The potential difference across the capacitor is reduced
  • No work is done by an external agent in taking the slab out
The distance between the plates of a parallel plate capacitor is d. A metal plate of thickness d/2 is placed between the plates. The capacitance would be then be
  • Unchanged
  • Initial
  • Zero
  • Doubled
A parallel plate capacitor consists of two circular plates each of radius 2 cm, separatrd by a distance of 0.1 mm If Voltage across the plates is at the rate of 5×1013 V/s, then the value of displacement current is
  • 5.50A
  • 5.56×103A
  • 2.28×104A
  • 5.56×102
Two identical particles of mass m carry a charge Q each . Initially one is at rest on a smooth horizontal plane and the other is projected along the plane directly towards first particle a large distance with speed v. The closed distance of approach be 
  • 14πε0Q2mv
  • 14πε04Q2mv2
  • 14πε02Q2mv2
  • 14πε03Q2mv2
For high frequency a capacitor offer
  • more reactance
  • less reactance
  • zero reactance
  • inifinite reactance
The plates of a parallel plate condenser are pulled apart with a velocity v. If at any instant their mutual distance of separation is x, the magnitude of the time of rate of change of capacity depends on x as follows : 
  • 1/x
  • 1/x2
  • x2
  • x
Equipotential surfaces are shown in fig, then the electric field strength will be 
1224828_1fdfa6cbc47c432ab0320203eec5d923.png
  • 100 Vm-1 along X-axis
  • 100 Vm-1 along Y-axis
  • 200 Vm-1 at an angle 1200 wirh X-axis
  • 50 Vm-1 at an angle 1800 wirh X-axis
The resultant capacitance between A and B in the following figure is equal to
1241952_b12ce9035b30437fb7f50021f1785e42.png
  • 1μF
  • 3μF
  • 2μF
  • 1.5μF
P, Q and R are three points in a uniform electric field. The electric potential is
1239393_3498dad3654c48978dae57f8b5049f86.PNG
  • minimum at R
  • minimum at Q
  • minimum at P
  • Same at all three points
A charged capacitor of capacitance C and having charge Q is to be connected with another uncharged capasitor of capasitance C' as shown till the steady state is reached , find the value of C' for heat liberated through the wires to be minimum.
1263382_ffcaa4db0fb44cbca33e3948c28e5305.png
  • zero
  • C
  • C /2
  • 2C
75% of the distance d between the parallel plates of a capacitor is filled with a meterial of dielectric constant K. Find the changed capacitance if original capacitance was C0.....................
  • (3KK+3)C0
  • (4KK+4)C0
  • (4KK+3)C0
  • (3KK+4)C0
Maximum charge on capacitor after switch is closed is
1244168_2e13f898e4b44df7acc285b5b66301e0.png
  • 2 CE
  • 4 CE
  • 6 CE
  • 7 CE
Two capacitors of 4 μFand 2 μF are connected in series with the battery. If total potential difference across the two capacitors is 200 volts then the ratio  of potential difference across one capacitor to another is
  • 1:2
  • 2:1
  • 1:4
  • 4:1
The capacitor is charged by closing the switch S. The witch is then opened and the capacitor is allowed to discharge. Take R1=R2=R3=R (Battery is ideal and connecting wire has negligible resistance). The fraction of the total heat generated, lost in R1 during discharging is :
  • 16
  • 13
  • 12
  • 23
The ratio of charge densities on the surface of two conducting spheres is 3 :lithe radii of t: the spheres are 4 cm and 8 cm the ratio of the electric potential on the surfaces of the sphere 2 is
  • 3 : 4
  • 3 : 1
  • 1 : 3
  • 4 : 9
The energy per unit volume of a dielectric medium is proportional to square of 
  • relative permittivity
  • charge
  • energy
  • electric intensity
The electric potential decreases uniformly from 120 V to 80 V as one moves on the X-axis from x=1cm to x=+1 cm. The electric field at the origin.
  • must be equal to 20V/cm
  • must be equal to 2.0V/cm
  • must be greater than 20V/cm
  • must be less than 20V/cm
The distance between the plates of a parallel plate capacitor is 3 mm and the potential 1 difference applied is 3×105V. If an electron travels from one plate to another, the change in its potential energy is
  • 3×105eV
  • 900eV
  • 108eV
  • Negligible
If electric intensity E is along the X-axis, then the equipotential surfaces are parallel to
  • XOY plane
  • XOZ plane
  • YOZ plane
  • None of these
Let  V0 be the potential at the origin in an electric field E=Exˆi+Eyˆj. The potential at the point (x,y) is:
  • V0xExyEy
  • V0+xEx+yEy
  • xEx+yEyV0
  • (x2+y2)E2x+E2yV0
The electric potential at a distance of 3m on the axis of a short dipole of dipole moment 4×1012 coulomb-metre is 
  • 1.33×103V
  • 4mV
  • 12mV
  • 27mV
The electric potential due to point charge at a point
  • May be approximately zero
  • May be positive
  • May be negative
  • Any of these
In order to increase the capacity of parallel plate condenser one should introduce between the plates, a sheet of
  • mica
  • tin
  • copper
  • stainless steel
A parallel plate capacitor of area 60cm2 and separation 3 mm is charged initially to 90μC. If medium between the plates gets slightly conducting and the p!ate loses the charge initially at rate of 2.5×108C/s, then what is the magnetic field between the plates?    
  • 2.5×108T
  • 2.0×107T
  • 1.63×1011T
  • ZERO
If electric field in  a region is zero, then electric potential in the region
  • Must be zero
  • Must not be zero
  • May be zero
  • None of these
Three capacitors 4, 6 and 12 μF  are connected in series to a 10 V source. The charge on the middle capacitor is
  • 10 μC
  • 20 μC
  • 60 μC
  • 5 μC
In figure two points A and B are located in a region of electric field. The potential difference VBVA is  
1293302_642afed671aa4f8cadaf6d16eaf32c86.png
  • Positive
  • Negative
  • Zero
  • None of these
Two charges 5μC and +10μC are placed 20 cm apart. The net electric field at the mid-point between the two charge is 
  • 4.5×105N/C directed towards +10μC
  • 13.5×105N/C directed towards 5μC
  • 13.5×105N/C directed towards +10μC
  • 4.5×105N/C directed towards 5μC
The change on capacitor c1
1303865_a4fbefe049b94e25b2adb1f97c57efdf.png
  • 0μc
  • 5μc
  • 10μc
  • none of these
In the following circuit the resultant capacitance between A and B is 1μF. Find the value of C :


1327539_108de9eab9da458d940873fd36570190.png
  • 2332μF
  • 3223μF
  • 1323μF
  • 2313
In the electric network shown, when no current flows through the 4Ω resistor in the arm EB, the potential difference between the points A and D will be : 

1302685_670c3d90227c447d9320b0dd2095635c.PNG
  • 3 V
  • 4 V
  • 5 V
  • 6 V
The radius of the gold nucleus is 6.6×1015m  and the atomic number is 79. The electric potential at the surface of the gold nucleus is :
  • 1.7×107V
  • 7.1×107V
  • 1.7×109V
  • 7.1×109V
Some charge Q is to be distributed on 3 concentric shell such that surface charge density on each shell is same as shown. Find the electric potential at r(<a) from point O.
1347673_cded0cd5840646d29d116c1616e5e854.png
  • Q(a+bc)4πε0(a2+b2+c2)
  • Q(a+b+c)4πε0(a2+b2+c2)
  • Q(a+b+c)4πε0(a2b2+c2)
  • Q(a+bc)4πε0(a2+b2c2)
The charges Q+q and +q are placed at the vertices of a right-angle isosceles triangle as shown below. The net electrostatic energy of the configuration is zero, it the value of Q is: 
1331792_b9eb64ca72a54afd84f61aa007cbd8c5.PNG
  • 2q2+1
  • 2q
  • q1+2
  • +q
Two condenser of 2μF and 4μF are connected in series. The p.d of 1200 volt. The p.d across 2μF is -
  • 400 V
  • 600 V
  • 800 V
  • 900 V
Potential difference between two points is equal to 
  • electric charge /time
  • work done/time
  • work done/charge
  • work done × charge
Two capacitors 'A' of 3μF and 'B' of 2μF are connected in series. 'A' can withstand a potential difference of 3 KV while 'B' can withstand 5 KV. What maximum potential difference can be applied across the combination?
  • 8KV
  • 6KV
  • 7.5KV
  • 8.3KV
The charge on a capacitor plate in a circuit, as a function of time, is shown in the figure:
What is the value of current at t=4s?
1332120_0c4669cddf464e62bcc1f83f816831bb.PNG
  • 3 μA
  • 2 μA
  • Zero
  • 1.5 μA
The energy stored in a parallel plate capacitor can be treated as the energy filled. The energy per unit volume, due to the electric field is :
  • E2
  • 12ϵ0E2
  • 12ϵ0E2
  • 12E2
The potential energy of a 1kg particle free to move alongthe x -axis is given byV(x)=(x44x22)J

The total mechanical energy of the particle is 21. Then, the maximum speed (in ms 1 ) is
  • 32
  • 2
  • 12
  • 2
 An infinite number of charges 'q' each are placed along the x - axis at x =1, x=4 ,x=8 and so on. If the distance are in meters calculate the electric potential at x=0
  • 3q8πE0
  • q2πϵ0
  • 2qπϵ0
  • 4qπϵ0
In the situation shown in figure, what should be the relation between Q and q so that electric potential at centre of the square is zero:
1330482_0485bbc720b24e49a55fae919d02f4a6.PNG
  • Q=q
  • Q=3q
  • Q=2q
  • Q=3q
The figure shows an experiment plot for discharging of a capacitor in an RC circuit. The time constant t of this circuit lies between 
1377845_fa536e3748c44f979e859708c64e3bc5.png
  • 0 and 50 sec
  • 50 and 100 sec
  • 100 and 150 sec
  • 150 and 200 sec
Two spheres of capacitance 3μF and 5 muF are charged to 300 V and 500 V respectibely and are connected together. The common potential in steady state will be :
  • 400 V
  • 425 V
  • 350 V
  • 375 V
In the capacitor shown in the circuit is charged to 5V and left in the circuit,in 12s the charge on the capacitor will become.
1396513_1ebe96fe877543b9a9a89171a51a8766.png
  • 10eC
  • e10C
  • 10e2C
  • e210C
The electric potential at a point (x,0,0) is given byV=[1000χ+1500χ+500χ3]
then the electric field at x=1m is (in volt/m)
  • 5500ˆi
  • 5500ˆi
  • 5500ˆi
  • Zero
Potential difference between the points B and C of the circuit is 
1393663_508c6295259146acb9e9a0b8225e55d0.PNG
  • (C2C1)V
  • (C4C3)V
  • (C2C3C1C4)(C1+C2+C3+C4)V
  • C1C4C2C3(C1+C2)×(C3+C4)V
An arc of radius r carries change. The linear density of charge is λ and the arc subtends a angle π3 at the center. What is electric potential at the center
  • λ4ε0
  • λ8ε0
  • λ12ε0
  • λ16ε0
The potential at a point, due to a positive charge of  10μC  at a distance of  9m  is
  • 105V
  • 103V
  • 106V
  • 104V
0:0:1


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