ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

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 relation V = IR represents

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

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

If 2.2 kilowatt power is transmitted through 1 10 ohm line at 22000 volt, the power loss in the form of heat will be

• 0.1 watt A
• 1 watt B
• 10 watt C
• 100 watt D

A certain charge liberates 0.8 g of oxygen. The same charge will liberate. how many g of silver?

• 108 g A
• 10.8 g B
• 0.8 g C
• 108/0.8 g D

In a Milikian's oil drop experiment the charge on an oil drop is calculated to be 6.35 x 10^-19C. The number of excess electrons on the drop is

• 3.9 A
• 4 B
• 4.2 C
• 6 D

The unit of resistance is

• volt A
• ampere B
• ohm C
• coat 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

The charge carriers in gases are

• electrons A
• ions B
• protons C
• ions and electrons D

Force acting upon a charged particle kept between the plates of a charged condenser if F. IF one of the plates of the condenser is removed, force acting on the same will become

• Zero A
• F/2 B
• F C
• 2F 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

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

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

The substances whose resistance decreases with the increase in temperature these substances have coefficient of

• positive temperature A
• negative temperature B
• absolute temperature C
• zero temperature D

Thermocouple is an arrangement of two different metals

• To convert heat energy in to electrical energy A
• To produce more heat B
• To convert heat energy into chemical energy C
• To convert electric energy in to heat energy 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

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

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

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

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

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

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 earth's potential is taken as

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

A 100 W, 200 V bulb is connected to a 160 volts supply. The actual power consumption would be

• 64 W A
• 80 W B
• 100 W C
• 125 W D

• 5μF A
• 10μF B
• 3μF C
• 6μF D

The electric intensity at infinite distance from the point charge will be

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

Electric generators which convert mechanical energy into

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

Heating effect caused by an electric circuit is written

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