ECAT Pre Engineering Physics Chapter 12 MCQ Test With Answer

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 potential difference across each resistance in series combination is

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

The thermistors are usually made of

• Metals with low temperature coefficient of resistivity A
• Metals with high temperature coefficient of resistivity B
• Metal oxides with high temperature coefficient of resistivity C
• Semi conducting materials having low temperature coefficient of resistivity 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

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

The conductivity of a superconductor is

• Infinite A
• Very large B
• Very small C
• Zero D

A one microfarad capacitor of a TV is subjected to 4000 V potential difference. The energy stored in capacitor is

• 8 J A
• 16 J B
• 4 x 10^-3J C
• 2 x 10^-3J 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

Resistor is a device which convert electric energy to

• Heat energy A
• Chemical energy B
• Elastic energy C
• All of the above D

The liquid which conduct current is known as

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

Three resistors of resistance 2,3 and 6 ohms are connected in parallel, their equivalent resistance is

• 11.0 ohm A
• 1.0 ohm B
• 7.0 ohm C
• 3.0 ohm D

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

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

The resistance of an incandescent lamp is

• Smaller when switched on A
• Greater when switched off B
• The same whether it is switch off or switch on C
• Greater when switched on 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 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

Surface density of charge is defined as

• Charge per unit volume A
• Charge per unit length B
• Charge per unit area C
• Charge per unit mass D

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

• Maximum A
• Minimum B
• Zero C
• Infinite 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

One electron volt is equal to

• 1.6 x 1019eV A
• 6.25 x 1018 eV B
• 1.6 x 1018 eV C
• 6.25 x 1019eV D

If two bulbs one of 60 W and other of 100 W are connected in parallel, then which one of the following will flow more?

• 60 W bulb A
• 100 W bulb B
• Both equally C
• None of these 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

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

The unit of resistivity is

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

• 5μF A
• 10μF B
• 3μF C
• 6μF D

The colour sequence in a carbon resistor in red, brown, orange and silver. The resistance of the resistor is

• 21 x 10³+ 10% A
• 23 x 10¹+ 10% B
• 21 x 10³+ 5% C
• 12 x 10³+ 5% D

The minimum resistance that can be obtained by connecting 5 resistance of 1/4Ωeach is

• 4/5Ω A
• 5/4Ω B
• 20Ω C
• 0.05 Ω D

The SI unit of electric field intensity is

• CN^-1 A
• NC^-1or Vm^-1 B
• JC^-1 C
• AV^-1 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

The SI unit of conductivity is

• ohm-m A
• ohm^-1m^-1 B
• ohm-m^-1 C
• ohm^-1m 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