ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

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

In case of a parallel plate capacitor if the plate separation is doubled and plate area is halved, the capacitance becomes

• Four-fold A
• One-half B
• One-fourth C
• Zero D

The energy required to charge a capacitor of 5μF by connecting D.C. source of 20 KV is

• 10 KJ A
• 5 KJ B
• 2 KJ C
• 1 KJ D

If a charged spherical conductor of radius 10 cm has potential V at a point distance 5 cm from its centre, then the potential at a point distance 15 cm from the centre will be

• 1/3 V A
• 2/3 V B
• 3/2 V C
• 3V D

• 5μF A
• 10μF B
• 3μF C
• 6μF D

One coulomb per second is equal to

• One volt A
• One ampere B
• One hom C
• One henry D

The relation between the charge Q of a parallel plate capacitor and the P.D between its plates is

• Q=V/C A
• Q=C/V B
• Q=1/2CV C
• Q=CV 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

The SI unit of electric flux is

• Weber A
• Nm²C^-1 B
• NmC^-1 C
• Nm^-2C 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

Coulomb's force between two point charges depends upon

• Magnitude of charges A
• Distance between them B
• Medium in which they are located C
• All of the above 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

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

The resistance of a conductor does not depend on its

• mass A
• resistivity B
• length C
• cross-sectional area 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

Electric potential of earth is taken to be zero because the earth is good

• Semiconductor A
• Conductor B
• Insulator C
• Dielectric D

Ohm is the unit of

• current A
• capacitance B
• energy C
• resistance 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

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

Battery is charged in motor cars, which is based on

• Chemical effect A
• Magnetic effect B
• Electric effect C
• None D

In a building, there are 15 bulbs of 40 watts, 5 bulbs of 100 watts, 5 fans of 80 watts and a heater of 1 kilowatt. The voltage of the electric main is 220 volts. The minimum efficiency of the main fuse of the building will be

• 0.4 A A
• 11.4 A B
• 9.8 A C
• 10.6 A D

The relation between charge 'Q' and current 'I' is given by

• Q = I/t A
• Q = It B
• Q = I²t C
• Q = I²/t D

A car battery has e.m.f 12 volt and internal resistance 5 x 10^-2ohm. If it draws 60 ampere current, the terminal voltage of the battery will be

• 5 volt A
• 3 volt B
• 15 volt C
• 9 volt 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

The relation V = IR represents

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

Electron volt is the unit of.

• Potential difference A
• Energy B
• Resistance C
• Capacitance D

Resistance of a conductor depends upon

• the quantity of current passing through it A
• the voltage applied between its end B
• its dimensions, physical state and nature of its material C
• all of the above D

For two resistance wires joined in parallel, the resultant resistance is 6/5 ohm. When one of the resistance wire breaks, the effective resistance becomes 2 ohm. The resistance of the broken wire is

• 3/5 ohm A
• 2 ohm B
• 6/5 ohm C
• 3 ohm D

The electric field intensity at a point due to a point charge

• Falls off inversely as the distance A
• Falls off inversely as the square of distance B
• Remains unchanged with distance C
• Increase directly as square of distance 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