ECAT Pre General Science Physics Chapter 12 MCQ Test With Answer

The SI unit of capacitance is

• Farad A
• Henry B
• Ohm C
• Volt D

A cube of metal is given a positive charge Q. For the above system, which of the following statements is true?

• Electric potential at the surface of the cube is zero A
• Electric potential within the cube is zero B
• Electric filed is normal to the surface of the cube C
• Electric filed varies within the cube D

The resistance of a conductor does not depend on its

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

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

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

Heating effect caused by an electric circuit is written

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

A uniform resistance wire of Length L and diameter d has a resistance R. Another wire of same material has length, 4L and diameter 2d, the resistance will be

• 2 R A
• R B
• R/2 C
• R/4 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

Some charge is being given to a conductor. Then its potential

• Is maximum at surface A
• Is maximum at centre B
• Is remain same throughout the conductor C
• Is maximum somewhere between surface and centre 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

Physicist George Simon ohm was a

• German physical A
• French physicist B
• Chinese physicist C
• Russian physicist D

A charge of 0.1 c accelerated through a potential difference of 1000V acquires kinetic energy

• 200 J A
• 100 J B
• 1000 J C
• 400 J 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 resistance of 20 cm long wire is 10Ω. When the length is changed to 40 cm. The new resistance is

• 10Ω A
• 20Ω B
• 30Ω C
• 40Ω D

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

• cathode A
• anode B
• electrolyte C
• position 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

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 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

A 50 volt battery is connected across 10 ohm resistor. The current is 4.5 A. The internal resistance of the battery is

• Zero A
• 0.5Ω B
• 1.1Ω C
• 5.0Ω D

In a charged capacitor the energy is stored in

• Both in positive and negative charges A
• Positive charges B
• The edges of the capacitor plates C
• The electric field between the plates D

The resistivity of a substance depends upon the

• length A
• mass B
• area C
• temperature 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 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 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 charge Q is divided into two parts q and Q - q and separated by a distance R. The force of repulsion between them will be maximum when

• q = Q/4 A
• q = Q/2 B
• q = ! C
• None of these D

• 5μF A
• 10μF B
• 3μF C
• 6μF 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

Two electric bulbs of 200 W and 100 W have same voltage. If R₁and R₂be their resistance respectively then

• R₁= 2R₂ A
• R₂= 2R₁ B
• R₂ = 4R₁ C
• R₁= 4R₂ D

The charge carriers in electrolyte are positive and negative

• protons A
• electrons B
• ions C
• none of these 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