Physics M.C.Q (1 Marks)

Assertion : A parallel plate capacitor is connected across battery through a key. A dielectric slab of constant K is introduced between the plates. The energy which is stored becomes K times.
Reason : The surface density of charge on the plate remains constant or unchanged.

Assertion : The tyres of aircraft's are slightly conducting.
Reason : If a conductor is connected to ground, the extra charge induced on conductor will flow to ground.

Assertion : Circuit containing capacitors should be handled cautiously even when there is no current.
Reason : The capacitors are very delicate and so quickly break down..

Assertion : The lightening conductor at the top of high building has sharp pointed ends.
Reason : The surface density of charge at sharp points is very high resulting in setting up of electric wind.

Assertion : The force with which one plate of a parallel plate capacitor is attracted towards the other plate is equal to square of surface density per e per unit area.
Reason : The electric field due to one charged plate of the capacitor at the location of the other is equal to surface density per e.

Assertion : At a point in space, the electric field points towards north. In the region, surrounding this point the rate of change of potential will be zero along the east and west.
Reason : Electric field due to a charge is the space around the charge

Assertion : Conductors having equal positive charge and volume, must also have same potential.
Reason : Potential depends only on charge and volume of conductor.

Assertion : The whole charge of a conductor cannot be transferred to another isolated conductor.
Reason : The total transfer of charge from one to another is not possible

Assertion : On going away from a point charge or a small electric dipole, electric field decreases at the same rate in both the cases.
Reason : Electric field is inversely proportional to square of distance from the charge or an electric dipole.

Assertion : The surface charge densities of two spherical conductors of different radii are equal. Then the electric field intensities near their surface are also equal.
Reason : Surface charge density is equal to charge per unit area.

Assertion : If a point charge q is placed in front of an infinite grounded conducting plane surface, the point charge will experience a force.
Reason : This force is due to the induced charge on the conducting surface which is at zero potential.

Assertion : Charge is quantized
Reason : Charge, which is less than 1 C is not possible

Assertion : Mass of ion is slightly differed from its element.
Reason : Ion is formed, when some electrons are removed or added so mass changes

Assertion : Charge is invariant.
Reason : Charge does not depends on speed of frame of reference.

Assertion : A charged capacitor is disconnected from a battery. Now if its plate are separated farther, the potential energy will fall.
Reason : Energy stored in a capacitor is equal to the work done in charging it.

Assertion : The capacity of a given conductor remains same even if charge is varied on it.
Reason : Capacitance depends upon nearly medium as well as size and shape of conductor.

Assertion : Annihilation of electron and positron is an example of decay of charges.
Reason : In the process of annihilation an electron and a positron combine to give a gamma particle.

Assertion : When charges are shared between any two bodies, no charge is really lost, but some loss of energy does occur.
Reason : Some energy disappears in the form of heat, sparking etc.

Assertion : Dielectric breakdown occurs under the influence of an intense light beam.
Reason : Electromagnetic radiations exert pressure.

Assertion : If a proton and an electron are placed in the same uniform electric field. They experience different acceleration.
Reason : Electric force on a test charge is independent of its mass.

Assertion : Electric lines of force cross each other.
Reason : Electric field at a point superimpose to give one resultant electric field.

Four metallic plates each with a surface area of one side A are placed at a distance d from each other. The plates are connected as shown in the circuit diagram. Then the capacitance of the system between a and b is

Assertion : A metallic shield in form of a hollow shell may be built to block an electric field.
Reason : In a hollow spherical shield, the electric field inside it is zero at every point.

Assertion : Electrons move away from a low potential to high potential region.
Reason : Because electrons has negative charge

Assertion : If the distance between parallel plates of a capacitor is halved and dielectric constant is made three times, then the capacitor becomes 6 times.
Reason : Capacity of the capacitor does not depend upon the nature of the material.

The variation of potential with distance R from a fixed point is as shown below. The electric field at R = 5 m is








 

The figure gives the electric potential V as a function of distance through five regions on x-axis. Which of the following is true for the electric field E in these regions

Which of the following graphs shows the variation of electric field E due to a hollow spherical conductor of radius R as a function of distance from the centre of the sphere

The electric field due to a uniformly charged sphere of radius R as a function of the distance from its centre is represented graphically by

What physical quantities may X and Y represent ? (Y represents the first mentioned quantity)







 

Between the plates of a parallel plate capacitor a dielectric plate is introduced just to fill the space between the plates. The capacitor is charged and later disconnected from the battery. The dielectric plate is slowly drawn out of the capacitor parallel to the plates. The plot of the potential difference across the plates and the length of the dielectric plate drawn out is

A fully charged capacitor has a capacitance ‘C’. It is discharged through a small coil of resistance wire embedded in a thermally insulated block of specific heat capacity ‘s’ and mass ‘m’. If the temperature of the block is raised by ‘ ∆T ’, the potential difference ‘V’ across the capacitance is

The plates of a parallel plate condenser are pulled apart with a velocity v. If at any instant their mutual distance of separation is d, then the magnitude of the time of rate of change of capacity depends on d as follows

The plates of a capacitor are charged to a potential difference of 320 volts and are then connected across a resistor. The potential difference across the capacitor decays exponentially with time. After 1 second the potential difference between the plates of the capacitor is 240 volts, then after 2 and 3 seconds the potential difference between the plates will be

In the given figure each plate of capacitance C has partial value of charge

Consider the situation shown in the figure. The capacitor A has a charge q on it whereas B is uncharged. The charge appearing on the capacitor B a long time after the switch is closed is

For the circuit shown, which of the following statements is true

In the given circuit if point C is connected to the earth and a potential of +2000 V is given to the point A, the potential at B is

Condenser A has a capacity of 15μF when it is filled with a medium of dielectric constant 15. Another condenser B has a capacity of 1 μF with air between the plates. Both are charged separately by a battery of 100 V. After charging, both are connected in parallel without the battery and the dielectric medium being removed. The common potential now is

A parallel plate capacitor of capacitance 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 

Figure given below shows two identical parallel plate capacitors connected to a battery with switch S closed. The switch is now opened and the free space between the plate of capacitors is filled with a dielectric of dielectric constant 3. What will be the ratio of total electrostatic energy stored in both capacitors before and after the introduction of the dielectric

In an RC circuit while charging, the graph of in i versus time is as shown by the dotted line in the diagram figure, where i is the current. When the value of the resistance is doubled, which of the solid curve best represents the variation of in i versus time