ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

Calculate the amount of charge flowing in 2 minutes in a wire of resistance 10Ωwhen a potential difference of 20 V is applied between its ends

• 120 C A
• 240 C B
• 20 C C
• 4 C 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

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

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

A 60 W bulb operates on 220 V supply. The current flowing through the bulb is

• 11/3 A A
• 3 A B
• 3/11 A C
• 6 D

Ohm established a relation between

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

A point charge A of charge +4μC and another B of charge -1μC are placed in air at a distance 1 m apart. Then the distance of the point on the line joining the charge B, where the resultant electric field is zero, is (in m)

• 2 A
• 1 B
• 0.5 C
• 1.5 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

Solar cell converts sunlight directly into

• potential energy A
• thermal energy B
• mechanical energy C
• electrical energy 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

The ratio of the gravitational force F_gto the electrostatic force F_ebetween two electrons at the same distance apart is approximately

• 9.8 A
• 24 x 10¹⁹ B
• 24 x 10⁴² C
• 24 x 10^-44 D

At ordinary temperature, an increase in temperature increases the conductivity of

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

• 5μF A
• 10μF B
• 3μF C
• 6μF 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

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

The unit of resistivity is

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

The SI unit of electric flux is

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

Current provided by a battery is maximum when

• Internal resistance equal to external resistance A
• Internal resistance is greater than external resistance B
• Internal resistance is less then external resistance C
• None of these 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

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

A metal plate of thickness half the separation between the capacitor plates of capacitance C is inserted. The new capacitance is

• C A
• C/2 B
• Zero C
• 2C D

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

• Maximum A
• Minimum B
• Zero C
• Infinite D

A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor

• Increases A
• Decreases B
• Remain unchanged C
• Becomes infinite D

A piece of fuse wire melts when a current of 15 ampere flows through it. With this current. If it dissipates 22.5 W, the resistance of fuse wire will be

• Zero A
• 10Ω B
• 1Ω C
• 0.10Ω 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 earth's potential is taken as

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

Which of the following represents an electric current?

• C^-1 A
• CS^-1 B
• J.S^-1 C
• dynes^-1 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

Capacitance of two or more capacitors

• Increases in series combination A
• Increases in parallel combination B
• Remains unchanged C
• None of the above D

The force between two chares 0.06 m apart is 5 N. If each charge is moved towards the other by 0.01 m, then the force between them will become

• 7.20 N A
• 11.25 N B
• 22.50 N C
• 45.00 D

The unit of resistance is

• volt A
• ampere B
• ohm C
• coat D