ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

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

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

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

The speed of randomly moving electrons depends upon

• pressure A
• volume B
• temperature C
• mass D

In a Milikian's oil drop experiment the charge on an oil drop is calculated to be 6.35 x 10^-19C. The number of excess electrons on the drop is

• 3.9 A
• 4 B
• 4.2 C
• 6 D

The conventional current in a circuit is defined as " current which passes from a point at higher potential to a point at lower potential as if it represent a movement of

• negative charges A
• positive charges B
• protons C
• electrons D

In bringing an electron towards another electron, electrostatic potential energy of system

• Decreases A
• Increases B
• Remains uncharged C
• Becomes zero 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

Physicist George Simon ohm was a

• German physical A
• French physicist B
• Chinese physicist C
• Russian physicist D

The SI unit of conductivity is

• ohm-m A
• ohm^-1m^-1 B
• ohm-m^-1 C
• ohm^-1m D

Two point charge +3μC and +8μC repel each other with a force of 40 N. If a charge of -5μC is added to each of them, then the force between then will become

• -10 N A
• +10 N B
• +20 N C
• -20 N D

Which one of the following has larger value of relative permitivity E_rat room temperature?

• Vaccum A
• Air B
• Glass C
• Water D

The conductivity of a superconductor is

• Infinite A
• Very large B
• Very small C
• Zero D

Electric generators which convert mechanical energy into

• solar energy A
• thermal energy B
• kinetic energy C
• electrical energy D

Which of the following does not obey ohm's law?

• Copper A
• Al B
• Diode C
• None D

Electric flux is defined by the relation

• E.A. A
• E x A B
• E/A C
• none of these D

When a dielectric material is introduced between the plates of a charged condenser the electric field between the plates

• Decreases A
• Increases B
• No change C
• May increase or decresase D

Three resistance 500,500 and 50 ohms are connected in series across 555 volts mains. The current flowing through them will be

• 0.52 A A
• 1 mA B
• 0.7 mA C
• 1.4 A D

An electric charge at rest is

• Only an electric field A
• Only a magnetic field B
• Both electric and magnetic fields C
• None of the above D

Two point charges A and B separated by a distance R attract each other with a force of 12 x 10^-3N. The force between A and B when the charges on them are doubled and distance is halved

• 1.92 N A
• 19.2 N B
• 12 N C
• 0.192 N D

An electric dipole is at the centre of a hollow sphere of radius r. The total normal electric flux through the sphere is (here Q is the charge and d is the distance between the two charges of the dipole)

• Q/4πr² A
• 2Q/4πr² B
• Q.d C
• Zero D

The SI unit of current is

• watt A
• coulomb B
• volt C
• ampere D

• 5μF A
• 10μF B
• 3μF C
• 6μF D

If the distance between the plates of a parallel plate condenser of capacity 10μF is doubled then new capacity will be

• 5μF A
• 20μF B
• 10μF C
• 15μF 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

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

One moving a charge of 20 coulombs by 2 cm, 2 J of work is done, then the potential difference between the points is

• 0.1 V A
• 8 V B
• 2 V C
• 0.5 V D

A capacitor is charged with a battery and then it is disconnected. A slab of dielectric is now inserted between the plates, then

• The charge in the plates reduces and potential difference increase A
• Potential difference between the plates increase, stored energy decreases and charge remains the same B
• Potential difference between the plates decreases and charge remains unchanged C
• None of the above D

Ohm established a relation between

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

If the length of the conductor is double and its cross sectional area is halved, its conductance will

• Increase four fold A
• Become one-fourth B
• Become one-half C
• Remains unchanged D