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

A medium of dielectric constant 'K' is introduced between the plates of parallel plate condenser. As a result its capcitance

• Increase k time A
• Decreases k times B
• Decreases 1/K times C
• Remains unchanged 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

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

Calculate the amount of charge flowing in 2 minutes in a wire of resistance 10Ωwhen a potential difference of 20 V is applied between its ends

• 120 C A
• 240 C B
• 20 C C
• 4 C D

If we plot graph between potential difference (V) and current (I) obeying ohm's law, it will give us

• parabola A
• straight line B
• hyper bola C
• ellipse 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 permitivity is

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

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

The graphical representation of ohm's law is

• hyperbola A
• straight line B
• ellipse C
• parabola D

Resistance of a conductor depends upon

• the quantity of current passing through it A
• the voltage applied between its end B
• its dimensions, physical state and nature of its material C
• all of the above 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

If a 40 watt light bulb burns for 2 hours. how much heat is generated

• 288 x 10³J A
• 288 x 10⁸J B
• 288 x 10⁵J C
• 288 x 10⁶J D

The resistivity of a substance depends upon the

• length A
• mass B
• area C
• temperature 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

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

Ohm established a relation between

• voltage and resistance A
• voltage and charge B
• voltage and current C
• voltage resistance and charge D

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

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

A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 KV, its kinetic energy will be

• 1840 KeV A
• 1/1840 KeV B
• 1 KeV C
• 920 KeV D

The SI unit of conductivity is

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

Battery is charged in motor cars, which is based on

• Chemical effect A
• Magnetic effect B
• Electric effect C
• None D

Two point charge +3μC and +8μC repel each other with a force of 40 N. If a charge of -5μC is added to each of them, then the force between then will become

• -10 N A
• +10 N B
• +20 N C
• -20 N 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

A closed surface contains two equal and opposite charges. The net electric flux from the surface will be

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

A piece of fuse wire melts when a current of 15 ampere flows through it. With this current. If it dissipates 22.5 W, the resistance of fuse wire will be

• Zero A
• 10Ω B
• 1Ω C
• 0.10Ω 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

• 5μF A
• 10μF B
• 3μF C
• 6μF 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