ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

Coulomb force, when any material medium is placed between two charges

• Increases A
• Decreases B
• Remain unchanged C
• None of these 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 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

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

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 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

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

A ten ohm electric heater operates on a 110 V line. Calculate the rate at which it develops heat in watts

• 1310 W A
• 670 W B
• 810 W C
• 1210 W D

The nature of capacity of electrostatic capacitor depends on

• Shape A
• Size B
• Thickness of plates C
• Area 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

Electron volt is the unit of.

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

Specific resistance of a wire depends upon

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

The unit of resistance is

• volt A
• ampere B
• ohm C
• coat D

The charge per unit time through any cross-section of a conductor is called

• capacitance A
• electric power B
• current C
• potential difference 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

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

Heating effect caused by an electric circuit is written

• H = I²Rt A
• H = I²R B
• H = IR²t C
• H = IR² D

Electron volt is the unit of

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

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

The SI unit of permitivity is

• Nm²C² A
• N^-1m^-2C² B
• NmC² C
• Nm²C^-1 D

Solar cell converts sunlight directly into

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

The current through a metallic conductor is due to the motion of

• protons A
• neutrons B
• electrons C
• free electrons D

The electrode connected with the positive terminal of the current source is called

• cathode A
• anode B
• electrolyte C
• position D

A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates. The quantity that remains unchanged is

• Charge Q A
• Potential V B
• Capacity C
• Energy U D

Potentiometer is more sensitive than voltmeter, because

• Voltmeter has a very high resistance A
• Voltmeter has a very low resistance B
• Potentiometer does not draw any current from a source of unknown potential difference C
• Potentiometer is sensitive 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

• 5μF A
• 10μF B
• 3μF C
• 6μF 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 field due to an infinite long thin wire at a distance R varies as

• 1/R A
• 1/R² B
• R C
• R² D