ECAT Pre General Science Physics Chapter 12 MCQ Test With Answer

If we increase the distance between two plates of the capacitor, the capacitance will

• Increase A
• Decrease B
• Remain same C
• First increase then decrease D

• 5μF A
• 10μF B
• 3μF C
• 6μF D

Which one of the following causes production of heat when current is set up in a wire?

• Fall of electrons from higher orbits to lower orbits A
• Inter-atomic collisions B
• Inter-electron collisions C
• Collisions of conduction electron with atoms D

Taking the earth to be a spherical conductor of diameter 12.8 x 10³km. Its capacity will be

• 711μF A
• 611μF B
• 811μF C
• 511μF 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

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

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

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

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 unit of resistance is

• volt A
• ampere B
• ohm C
• coat D

The electric lines of force are

• Imaginary A
• Physically existing everywhere B
• Physically existing near the charge C
• All of the above D

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

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

When an electron is accelerated through a P.D. of an one volt, it will acquire energy equal to

• One joule A
• One erg B
• One electron volt C
• None of these D

In a voltmeter the conduction takes place due to

• Electrons only A
• Holes only B
• Electrons and holes C
• Electrons and ions D

Electric flux is defined by the relation

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

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

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

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

• Decreases A
• Increases B
• Remains uncharged C
• Becomes zero 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 value of electrical constant of proportionality k is

• 9 x 10⁹Nm²C^-2 A
• 9 x 10^-9Nm²C^-2 B
• 9 x 10¹⁰Nm²C² C
• 9.85 x 10^-12N^-1C^-2 D

The potential difference across each resistance in series combination is

• same A
• different B
• zero C
• none of these D

The liquid which conduct current is known as

• heating effect A
• chemical energy B
• electrolyte C
• ohm's law D

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

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

The excess (equal in number) of electrons that must be placed on each of two small spheres spaced 3 cm apart, with force of repulsion between the spheres to be 10^-19N, is

• 25 A
• 225 B
• 625 C
• 1250 D

The material in the form of wire or rod or plate which leads the current into or cut of the electrolyte is known as

• voltmeters A
• resistance B
• electrode C
• current 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

Which of the following represents an electric current?

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

The electric flux from a closed surface

• Is independent of the shape of the surface A
• Depends on the charge enclosed by the surface B
• Both a and b C
• None of the above D

Electric generators which convert mechanical energy into

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