ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

Ohm established a relation between

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

Surface density of charge is defined as

• Charge per unit volume A
• Charge per unit length B
• Charge per unit area C
• Charge per unit mass D

If the distance of separation between two chares is increased, the electrical potential energy of the system will

• Increase A
• Decrease B
• May increase or decrease C
• Remain the same D

The graphical representation of ohm's law is

• hyperbola A
• straight line B
• ellipse C
• parabola 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

When three identical bulbs of 60 watt, 200 volt rating are connected in series to a 200 volt supply, the power drawn by them will be

• 180 watt A
• 10 watt B
• 20 watt C
• 60 watt D

The electric intensity outside the two oppositely charged parallel metal plates is

• Maximum A
• Minimum B
• Zero C
• Infinite 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

• 5μF A
• 10μF B
• 3μF C
• 6μF 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

If the two charges in Coulomb's law have double distance between them, then electric force

• Becomes two-fold A
• Becomes four-fold B
• Remains the same C
• None of these D

The relation V = IR represents

• Ampere law A
• Faraday's law B
• Ohm's law C
• Len's law D

A point charge Q is placed at the mid-point of a line joining two charges. 4q and q. if the net force on charge q is zero. then Q must be equal to

• -q A
• +q B
• -2q C
• +4q D

The unit of resistivity is

• ohm A
• ohm-m² B
• ohm-meter C
• ohm-m^-1 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

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

• Copper A
• Al B
• Diode C
• None 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 SI unit of current is

• watt A
• coulomb B
• volt C
• ampere 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 electric potential at the surface of an atomic nucleus (Z = 50) of radius 9.0 x 10^-15 is

• 9 x 10⁵V A
• 9 V B
• 8 x 10⁶V C
• 80 V 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

Electric generators which convert mechanical energy into

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

Ohm's law states that

• The current through a resistor is directly proportional to the applied voltage A
• The voltage across a resistor is directly proportional to the current passing through it B
• Resistance is the constant of proportionality between the voltage and current C
• all of these 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

A condenser of capacity 50μF is charged to 10 V.The energy stored is

• 1.25 x 10^-3J A
• 3.75 x 10^-3J B
• 2.5 x 10^-3J C
• 5 x 10^-3J 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

One electron volt is equal to

• 1.6 x 1019eV A
• 6.25 x 1018 eV B
• 1.6 x 1018 eV C
• 6.25 x 1019eV D

A hollow insulated conduction sphere is given a positive charge of 10μC. What will be the electric field at the centre of the sphere if its radius is 2 meters?

• Zero A
• 5μC m^-2 B
• 20μC m^-2 C
• 8μC m^-2 D

Ohm is the unit of

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

A conducting wire is drawn to double its length. Final resistivity of the material will be

• Double of the original one A
• Half of the original one B
• One fourth of the original one C
• Same as original one D