CBSE Questions for Class 12 Medical Physics Electrostatic Potential And Capacitance Quiz 1 - MCQExams.com

The plates of a parallel-plate capacitor are not exactly parallel. The surface charge density, therefore,
  • is smallest where the plates are closet
  • is higher at the closer end
  • will not be uniform
  • each plate will have the same potential at each point
In the given circuit, if potential difference between points $$A$$ and $$B$$ is $$4V$$, then, resistance $$X$$ is:-
1121306_20d3ee636c144e19a49efa85d80b755d.PNG
  • $$5 \Omega$$
  • $$10 \Omega$$
  • $$15 \Omega$$
  • $$20 \Omega$$
What is the S.I. unit of electric potential? 
  • ampere
  • volt
  • volt.m
  • coulomb
A battery is used to charge a parallel plate capacitor till the potential difference between the plates becomes equal to the electromotive force of the battery. The ratio of the energy stored in the capacitor and the work done by the battery will be :
  • $$1$$
  • $$2$$
  • $$\dfrac{1}{4}$$
  • $$\dfrac{1}{2}$$
An electric charge $$10^{-3}\mu C$$ is placed at the origin $$(0,0)$$ of X - Y co-ordinate system. Two points A and B are situated at $$(\sqrt{2},\sqrt{2})$$ and $$(2, 0)$$ respectively. The potential difference between the points A and B will be:
  • $$9$$ volt
  • zero
  • $$2$$ volt
  • $$4.5$$ volt
A parallel plat capacitor is made of two circular plates separated by a distance of $$5 mm$$ and with a dielectric of dielectric constant $$2.2$$ between them. When the electric field in the dielectric is $$3 \times 10^4$$V/m, the charge density of the positive plate will be close to:
  • $$3 \times 10^4 C/m^2$$
  • $$6 \times 10^4 C/m^2$$
  • $$6 \times 10^{-7} C/m^2$$
  • $$3 \times 10^{-7} C/m^2$$
A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor
  • decreases
  • remains unchanged
  • becomes infinite
  • increases.
A parallel plate capacitor has a dielectric slab of dielectric constant K between its plates that covers 1/3 of the area of its plates, as shown in the figure. The total capacitance of the capacitor is C while that of the portion with dielectric in between is C$$_1$$. When the capacitor is charged, the plate area covered by the dielectric gets charge Q$$_1$$ and the rest of the area gets charge Q$$_2$$. The electric field in the dielectric is E$$_1$$ and that in the other portion is E$$_2$$. Choose the correct option/options, ignoring edge effects :

113720.jpg
  • $$\displaystyle \frac{E_1}{E_2} = 1$$
  • $$\displaystyle \frac{E_1}{E_2} = \frac{1}{K}$$
  • $$\displaystyle \frac{Q_1}{Q_2} = \frac{3}{K}$$
  • $$\displaystyle \frac{C}{C_1} = \frac{2+K}{K}$$
What is the electric potential at a distance of 9 cm from 3 nC?
  • $$270 V$$
  • $$3 V$$
  • $$300 V$$
  • $$30 V$$
A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
  • The change in energy stored is $$\frac {1}{2}CV^2\left (\frac {1}{K}-1\right )$$
  • The charge on the capacitor is not conserved
  • The potential difference between the plates decreases K times
  • The energy stored in the capacitor decreases K times
The diagrams below show regions of equipotentials.
A positive charge is moved from A to B in each diagram.
638372_d9c3bdbca79d420f82dbf0acba45d4c3.png
  • Maximum work is required to move $$q$$ in figure (b)
  • Maximum work is required to move $$q$$ in figure(c)
  • In all the cases the work done is the same.
  • Minimum work is required to move $$q$$ in figure(a)
Two parallel metal plates having charges +Q and -Q face each other at a certain distance between them. If the plates are now dipped in kerosene oil tank, the electric field between the plates will :
  • become zero
  • increase
  • decrease
  • remains same
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
In figure, a particle has mass $$m=5g$$ and charge $$q'=2\times {10}^{-9}C$$ starts from rest at point $$a$$ and moves in a straight line to point $$b$$. What is its speed $$v$$ at point $$b$$?
468224_caaa726b3ae144c0bb75d54ffe4de435.png
  • $$2.65\ {cms}^{-1}$$
  • $$3.65\ {cms}^{-1}$$
  • $$4.65\ {cms}^{-1}$$
  • $$5.65\ {cms}^{-1}$$
Two identical conductors of copper and aluminium are placed in an identical electric field. What is the magnetic of induced charge in the aluminium?
  • Less than in copper
  • Equal to that in copper
  • Greater than in copper
  • Zero
An electric charge $${10}^{-3}\mu C$$ is placed at the origin $$(0,0)$$ of $$(x,y)$$ co-ordinate system. Two points $$A$$ and $$B$$ are situated at $$(\sqrt {2}, \sqrt {2})$$ and $$(2,0)$$ respectively. The potential difference between the points $$A$$ and $$B$$ will be:
  • $$4.5\ V$$
  • $$9\ V$$
  • $$zero$$
  • $$2\ V$$
A parallel plate capacitor with air as a dielectric has capacitance $$C$$. A slab of dielectric constant $$K$$, having same thickness as the separation between the plates is introduced so as to fill one-fourth of the capacitor as shown in the figure. The new capacitance will be:
740455_cbf515703ae84b7486848906071feee4.png
  • $$(K + 3)\dfrac {C}{4}$$
  • $$(K + 2)\dfrac {C}{4}$$
  • $$(K + 1)\dfrac {C}{4}$$
  • $$\dfrac {KC}{4}$$
$$100J$$ of work is done when $$2 \mu C$$ charge is moved in an electric field between two points. The p.d. between the points is
  • $$2\times10^{-4}V$$
  • $$2\times10^{-8}V$$
  • $$2\times10^{-6}V$$
  • $$5\times10^{7}V$$
In the given figure each plate of capacitance C has value of charge -
1215243_e0daafafeffc4bd3b607c71bd4175edf.png
  • $$CE$$
  • $$\cfrac { { CER }_{ 1 } }{ R_{ 2 }-r } $$
  • $$\cfrac { { CER }_{ 2 } }{ R_{ 2 }+r } $$
  • $$\cfrac { { CER }_{ 1 } }{ R_{ 1 }-r } $$

In a charged capacitor the energy is stored in:

  • both in positive and negative charges
  • positive charges
  • the edges of the capacitor plates
  • the electric field between the plates

When air is replaced by a dielectric medium of constant $$K$$, the capacity of the condenser:

  • increases $$K$$ times
  • increases $$K^{2}$$ times
  • remains unchanged
  • decreases $$K$$ times
Space between the plates of a parallel plate capacitor is filled with a dielectric slab. The capacitor is charged and then the supply is disconnected to it. If the slab is now taken out , then:
  • work is not done to take out the slab
  • energy stored in the capacitor reduces
  • potential difference across the capacitor is decreased
  • potential difference across the capacitor is increased

A parallel plate condenser is charged by connecting it to a battery. The battery is disconnected and a glass slab is introduced between the plates. Then, 

  • potential increases
  • electric intensity incrases
  • energy decreases
  • capacity decreases
Fill in the blank:

In order to increase the capacity of a parallel plate condenser,  one should introduce a sheet of  $$\underline{\hspace{0.5in}}$$ between the plates (assume that the space is completely filled).
  • Mica
  • Tin
  • Copper
  • Stainless Steel
The capacity of a parallel plate air condenser is $$2\ \mu F$$. If a dielectric of dielectric constant $$4$$ is introduced between the plates, its new capacity is:
  • $$1.5\ \mu F$$
  • $$0.5\ \mu F$$
  • $$8\ \mu F$$
  • $$6\ \mu F$$

A metal plate of thickness half the separation between the capacitor plates of capacitance C is inserted. The new capacitance is:

  • C
  • $$\frac{C}{2}$$
  • zero
  • 2C
In an electrical circuit, which of the following quantities is analogous to temperature?
  • Potential
  • Resistance
  • Current
  • Charge

A parallel plate capacitor is first charged and then isolated , and a dielectric slab is introduced between the plates. The quantity that remains unchanged is:

  • charge $$Q$$
  • potential $$V$$
  • capacity $$C$$
  • energy $$U$$
Two capacitors of capacity $$C_1$$ and $$C_2$$ are connected in parallel, then the equivalent capacity is:
  • $$C_1+C_2$$
  • $$C_1C_2/(C_1+C_2)$$
  • $$C_1/C_2$$
  • $$C_2/C_1$$
$$1$$ volt is equal to
  • $${1 \ Joule}$$
  • $$\dfrac{1 \ Joule}{1 \ Coulomb}$$
  • $$\dfrac{1 \ Joule}{1 \ meter}$$
  • $$\dfrac{1 \ Newton}{1 \ Coulomb}$$
State whether given statement is True or False.
Electric potential at a point in an electric field is defined as the work done in moving a unit positive charge from infinity to that point.
  • True
  • False
What is the shape of the equipotential surface for the line charge ?
  • Sphere
  • Cylinder
  • It will depend upon the type of charge
  • Can't say
The electric volt is a measure of electrical potential. Identify which of the following can be defined as a volt.
  • Opposition to electrical motion
  • Number of particles in motion
  • Work per unit charge
  • Field strength per unit of force
  • Electrostatic discharge
A one microfarad capacitor of a TV is subjected to 4000 V potential difference. The energy stored in capacitor is :
  • 8J
  • 16 J
  • $$4\times 10^{-3}J$$
  • $$2\times 10^{-3}J$$

The equivalent capacity between the points ‘A’ and ‘B’ in the following figure will be:


9380_eab57c0adcaa489487bb90d2d67adf19.png
  • $$9 \mu F$$
  • $$1 \mu F$$
  • $$4.5 \mu F$$
  • $$6 \mu F$$
The work done in moving a single positive charge from infinity to a point is called ..... at that point
  • Electricity
  • Electric potential
  • Potential gradient
  • None of these
To bring a unit positive charge from infinity to a point in an electric field, some work has to done, which is called:
  • potential energy
  • electric potential
  • electric field
  • electric induction

Three capacitors of $$3 \mu F, 2 \mu F $$ and $$6 \mu F$$ are connected in series. When a battery of 10V is connected to this combination then charge on $$3 \mu F$$capacitor will be :

  • $$5 \mu C$$
  • $$10 \mu C$$
  • $$15 \mu C$$
  • $$20 \mu C$$
For capacitors in the series combination, the total capacitance C is given by

  • $$C=(\cfrac{1}{C_1}+\cfrac{1}{C_2} + ......)$$
  • $$C = C_{1} + C_{2} +$$ .......
  • $$\cfrac{1}{C}=(\cfrac{1}{C_1}+\cfrac{1}{C_2}+.....)$$
  • $$\cfrac{1}{C} = C_{1} + C_{2} +$$ ........
There is no flow of current between two equally charged identical spheres when connected, because, they have the same 
  • quantity of charge
  • potential
  • capacity
  • ratio of potential per unit charge
Name the unit of electrical potential :
  • Coulomb
  • Watt
  • Joule
  • Volt
Electric potential is :
  • a scalar quantity
  • a vector quantity
  • neither scalar nor vector
  • sometimes scalar and sometimes vector
1 volt = ?
  • 1 joule
  • 1 joule per coulomb
  • 1 coulomb per metre
  • 1 newton per coulomb
When a dielectric is introduced between the plates of a condenser, the capacity of condenser :
  • increases
  • decreases
  • remains same
  • none of these
Which material sheet should be placed between the plates of a parallel plate condenser in order to increase its capacitance ?
  • mica
  • copper
  • tin
  • iron
Eight identical spherical mercury drops charged to a potential of 20 v each are coalesced into a single spherical drop:
  • The internal Energy of the system remains the same
  • The new potential of the drop is 80 V
  • Internal Energy of he system decreases
  • The potential remains the same i.e. 20 v
When a thin mica sheet is placed between the plates of a condenser then the amount of charge, so compared to its previous value, on its plates will become:
  • unchanged
  • zero
  • less
  • more
One Volt is equal to:
  • 1 Joule
  • 1 Newton/Coulomb
  • 1 Joule/Coulomb
  • 1 Coulomb/Newton
A number of capacitors, each of equal capacitance $$C$$, are arranged as shown in the figure. The equivalent capacitance between $$A$$ and $$B$$ is :

155152_41bfd52f8ec44bb6a325e5004ac1f90f.png
  • $${ n }^{ 2 }C$$
  • $$(2n+1)C$$
  • $$\cfrac { (n-1)n }{ 2 } C\quad $$
  • $$\cfrac { (n+1)n }{ 2 } C\quad $$
The capacity of a parallel plate condenser is inversely proportional to ___________.
  • Area of each plate
  • Dielectric constant
  • Permittivity of medium
  • Distance between two plates
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 12 Medical Physics Quiz Questions and Answers