ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

In a charged capacitor the energy is stored in

• Both in positive and negative charges A
• Positive charges B
• The edges of the capacitor plates C
• The electric field between the plates D

• 5μF A
• 10μF B
• 3μF C
• 6μF D

If an electron of charge 'e' is accelerated through a potential difference V., it will acquire energy

• Ve A
• V/e B
• e/V C
• 2Ve D

At any point on the right bisector of the line joining two equal and opposite charges

• At electric field is zero A
• The electric potential is zero B
• The electric potential decreases with increasing distance from the centre C
• The electric field is perpendicular to the line joining the charges D

Specific resistance of a wire depends upon

• Length A
• Cross-section area B
• Mass C
• None D

The powers of tow electric bulbs are 100 W and 200 W. Both of them are joined with 220 V mains. The ratio of resistances of their filaments will be

• 1 : 2 A
• 2 : 1 B
• 1 : 4 C
• 4 : 1 D

A medium of dielectric constant 'K' is introduced between the plates of parallel plate condenser. As a result its capcitance

• Increase k time A
• Decreases k times B
• Decreases 1/K times C
• Remains unchanged D

The potential difference across the conductors should be maintained constant by connecting the ends of wire to the terminal of a device called a source of

• power A
• current B
• resistance C
• temperature D

The electric field will be uniform

• Near a positive point charge A
• Near a negative point charge B
• Between two oppositely charged parallel metal plates C
• None of above D

Ohm established a relation between

• voltage and resistance A
• voltage and charge B
• voltage and current C
• voltage resistance and charge D

In RC series circuit the time during which the capacitor acquires 0.63 times the equilibrium charge is called

• Time constant A
• Decay constant B
• None of these C
• All of above D

The substances whose resistance decreases with the increase in temperature these substances have coefficient of

• positive temperature A
• negative temperature B
• absolute temperature C
• zero temperature D

The capacitance of a parallel plate capacitor depends upon

• Area of the plates A
• Separation between the plates B
• Medium between the plates C
• All of the above D

What is the current is a 2 x 10⁶ohm resistor having a potential difference of 2 x 10³volts?

• 10^-1A A
• 10^-2A B
• 10^-4A C
• 1 mA D

Which one of the following is the unit of electric field intensity

• JC^-1 A
• Vm^-1 B
• Cm^-1 C
• CJ^-1 D

The electric flux is linked with a surface will be maximum when

• The surface is held parallel to the electric field A
• The surface is held perpendicular to the electric field B
• The surface makes an angle of 45° with the electric field C
• All of the above D

If two bulbs one of 60 W and other of 100 W are connected in parallel, then which one of the following will flow more?

• 60 W bulb A
• 100 W bulb B
• Both equally C
• None of these D

The force of repulsion between two point charges is F, when these are at a distance 0.1 m apart. Now the point charges are replaced by sphere of radii 5 cm each having the same charge as that of the respective point charges. The distance between their centre is again kept 0.1 m ; then the force of repulsion will

• Increase A
• Decrease B
• Remain F C
• Become 10F/9 D

If electric and gravitational force on an electron in a uniform electric field will be

• E=mg/q A
• E=q/mg B
• E=,g/q C
• E=qg/m D

A cube of metal is given a positive charge Q. For the above system, which of the following statements is true?

• Electric potential at the surface of the cube is zero A
• Electric potential within the cube is zero B
• Electric filed is normal to the surface of the cube C
• Electric filed varies within the cube D

If one volt is needed to cause a current of one ampere to flow in a conductor, its resistance is

• one ohm A
• one joule B
• one volt C
• one ampere D

An alpha particle is accelerated through a potential difference of 10⁶volt. Its kinetic energy will be

• 1 MeV A
• 2 MeV B
• 4 MeV C
• 8 MeV D

Some charge is being given to a conductor. Then its potential

• Is maximum at surface A
• Is maximum at centre B
• Is remain same throughout the conductor C
• Is maximum somewhere between surface and centre D

Three resistors of resistance 2,3 and 6 ohms are connected in parallel, their equivalent resistance is

• 11.0 ohm A
• 1.0 ohm B
• 7.0 ohm C
• 3.0 ohm D

Ohm is the unit of

• current A
• capacitance B
• energy C
• resistance D

The minimum charge on any object can not be less than

• 1.6 x 10^-19C A
• 3.2 x 10^-19C B
• 1.0 C C
• 4.8 x 10^-19C D

The electric intensity at infinite distance from the point charge will be

• Infinite A
• Positive B
• Zero C
• Negative D

The resistance of the given conductor can be increased by

• Increasing the area A
• Changing resistivity B
• Decreasing the length C
• None of the above because change does not matter because in any case the volume remains the same D

Equal charges are given to two spheres of different radii. The potential will

• Be more on the smaller sphere A
• Be more on the bigger sphere B
• Be equal on both the sphere C
• Depend on the nature of the material of the sphere D

If the resistance of 2 ohm and 4 ohm are connected in parallel, the equivalent resistance will be

• 6 ohm A
• 4 ohm B
• zero ohm C
• 1.33 ohm D