# TOP 100+ Electric Charges And Fields Neet Questions and Answers

In this post we are going to discuss some most important Electric Charges And Fields Neet Questions and Answers. Electricity surrounds you, inside and outside. The study of electricity is called Electro-magnetism. The most fundamental thing about electricity is the charges and fields around us. Here are some answers to these questions.

## Electric Charges And Fields Neet Questions

#### 1. If an object is positively charged, theoretically the mass of the object ______

a) Increases slightly by a factor of 9.11*10-31 kg
b) Decreases slightly by a factor of 9.11*10-31 kg
c) Remains the same
d) May increase or decrease

Explanation: If an object is positively charged it loses some of its electrons. The mass of an electron is 9.11*10-31 kg. So, if a positively charged body loses ‘n’ number of electrons, it mass decrease by the amount n*9.11E-31kg.

#### 2. Why is gold used in the Gold-leaf electroscope?

a) Gold is easily available in nature
b) Gold is malleable
c) Gold is conducting in nature
d) Gold is cheap

Explanation: Though gold is a costly metal it is used in electroscope because of the property malleability. This means very thin and light sheets can be formed from gold simply by hammering or rolling and hence the deflection of the light gold plates increases.

#### 3. What happens to the plates of the apparatus if we measure alternating charge using a Gold-leaf oscilloscope?

a) It doesn’t diverge at all
b) It diverges momentarily
c) The plates give a proper divergence
d) The degree of divergence increases and decreases repeatedly

Explanation: The divergence of the plates of the Gold-leaf oscilloscope depends only on the presence of a charge, not on the quality of charge i.e. positive or negative. So, if the charge changes from positive to negative and vice versa the degree of divergence of the plates remains the same.

#### 4. Dr. Gilbert tried to hold a brass rod by hand and induce static electricity in it by friction. Why did he fail?

a) Static electricity is induced only on insulators while brass is conducting
b) The induced static charge flew through his hand and body to the ground
c) The static charge was not produced at all
d) It is not possible to induce static electricity by friction

Explanation: The human body is a good conductor and hence the charge produced by friction flew through his body to the ground. We can tackle the problem simply by holding the brass rod with the help of some insulated holder.

#### 5. Gold-leaf electroscope can be used _______

a) Only to detect the presence of charge
b) To detect the presence of charge as well as its nature (positive or negative)
c) To measure the surface charge density
d) To measure current

Explanation: If the apparatus is initially in contact with some positively charged body and then comes in contact with another charged body and if the divergence increases we can deduce that the second body is also positively charged. If the divergence decreases then the second body must be negatively charged.

#### 6. 1 Coulomb = ________ Electro Static Unit.

a) 3*109
b) 3*108
c) 1.602*10-19
d) 2*109

Explanation: 1 Coulomb means 3*109 Electro Static Unit of charge. Coulomb and ESU are two different units of charge and their conversion formula is necessary. Coulomb is the unit of charge in the SI system and esu is the unit of charge in the CGS system.

#### 7. Number of electrons in 1 Coulomb charge is _________

a) 6.25*1021
b) 6.25*1020
c) 6.25*1025
d) 6.25*1023

Explanation: Electron has the charge of 1.602*10-19 Coulomb. So, the number of electrons in 1 Coulomb of charge is $$\frac{1}{1.602*10^{-19}}$$ = 6.25*1021. This huge number of electrons can be accumulated to form 1C of charge. Thus, we can conclude that we need Avogadro’s number of electrons (approximately) to get 100C charges.

#### 8. Two equally charged spheres attract each other. Now if they touch each other then they will _____

a) Attract each other with the same amount of force
b) Repel each other
c) Attract each other with less amount of force
d) Don’t attract or repel

Explanation: The two spheres are oppositely charged by the same amount. So if they come in contact, both of their charges are neutralized. So they become uncharged and don’t attract or repel each other.

#### 9. Which among the following cannot be the charge of a charged body?

a) 4.8*10-14 Coulomb
b) 6.4*10-15 Coulomb
c) 5*10-14 Coulomb
d) 3.2*10-10 Coulomb

Explanation: Charge of a body must be an integral multiple of charge of an electron. 5*10-14 is not an integral multiple of (1.602*10-19 Coulomb) which is equal to the charge of an electron. But we can see that 4.8, 6.4, 3.2 are integral multiples of 1.6.

#### 10. Current carrier in conductors is ____

a) Electron
b) Proton
c) Neutron
d) Positron

Explanation: Conductors have lots of free electrons that can carry electricity if the potential difference is applied across them. Protons are positively charged particle and Neutron are electrically neutral. They don’t carry electricity in conductors.

#### 11. Which group among the following is insulator?

a) Silver, copper, gold
b) Paper, glass, cotton
c) The human body, wood, iron
d) Glass, copper, paper

Explanation: Glass, paper, and cotton are good quality insulators. The rest options contain one or more conducting materials. Silver is the best conductor material available in nature. But it is costly, so it can’t be used in the electricity distribution system.

#### 12. The band gap between the valence band and conduction band is the measure of ______

a) The conductivity of the material
b) The resistivity of the material
c) Charge density
d) Ease of ionization

Explanation: The more the band gap between the valence band and conduction band, the worse is the conductivity of the material. For conductors, there are overlapping bands. So, conductors can carry electricity. But there is a huge energy gap in the case of insulators. So, they don’t carry electricity at all.

#### 13. The rubber used in the wheels of aero-plane is _________

a) Perfect insulator
b) Slightly conducting
c) Can be an insulator or conducting
d) Semiconductor

Explanation: Due to high friction during takeoff, a huge amount of charge is produced on the rubber of the wheel of a plane. This charge must be sent to the ground. So, the rubber used is slightly conducting, else the huge charge produced may produce a spark and can cause an accident.

#### 14. Insulation breakdown may occur at _______

a) High temperature
b) Low temperature
c) At any temperature
d) Depends on pressure

Explanation: At high temperatures, electrons of insulators get excited and then the electrons can overcome the large energy band gaps between valence and conduction bands. So a large number of electrons travel to the conduction band and they act as conductor i.e. insulation breakdown occurs.

#### 15. Superconductors have __________

a) Almost zero resistivity
b) Very high resistivity
c) Temperature-dependent resistivity
d) Moderate value of resistivity

Explanation: Semiconductors are those which carry current with almost zero resistivity at a very low temperature (example: Lead at -272-degree centigrade). So, they have a very huge amount of current flow through them.

#### 16. If a positively charged sphere is taken close to another uncharged sphere then which of the following statements is true?

a) Induction and attraction occur simultaneously
b) Induction occurs before the attraction
c) Attraction occurs before induction
d) Attraction or repulsion may occur

Explanation: If two bodies are taken close to each other, a positively charged body induces a negative charge on another body and then they attract each other. So, induction occurs before attraction. This phenomenon is also true for magnetic induction.

#### 17. Induction occurs due to ______

a) Movement of electron
b) Leakage of charge
c) Ionization of atoms
d) Uniform charge distribution

Explanation: When a positive or negative charged body comes close to another body, the electrons of the second body redistribute themselves. Electrons of the second body are attracted by the positively charged body and repelled by the negatively charged body.

#### 18. A charge is being induced to a sphere with the help of another charged sphere. The extent of induction increase if ____________

a) The distance between the sphere increases
b) The distance between the sphere decreases
c) The two spheres are kept in contact with each other
d) Remains same irrespective of the distance between the spheres

Explanation: The extent of induction increases if both the spheres are kept close to each other because the more electrons in the uncharged sphere are attracted or repelled by the charged sphere, so the extent of induction increases.

#### 19. +q, +2q, +3q, +4q, ……(up to +20q) charges are situated at coordinates (0,0) , (1,0) ,(2,0) , ….. (Up to 20). What is the total charge stored in the system?

a) +20q
b) +210q
c) +420q
d) +190q

Explanation: As charge is additive, total charge will be (1+2+3+4+…. +20)*q=$$\frac{20*21}{2}$$*q= 210q. But if the polarities of the charges are different i.e. some of them are positive and some are negative, then the result will be different. We have to add separately the positive charges and the negative charges.

#### 20. A charged conductor has its charge only on its outer surface. This statement is true for which of the following?

a) For all conductors
b) Only for spherical conductors
c) For hollow conductors
d) For those conductors which don’t have sharp edges

Explanation: Charge remains on the outer surface of a conductor, irrespective of the shape and size of the conductor and also for hollow and solid conductors both. But if there is a sharp edge in the conductor, surface charge density will be more at that point. The surface charge density is uniform in the case of a sphere.

#### 21. What is the unit of surface charge density in the SI unit?

a) C
b) C/m
c) C/m2
d) C/m3

Explanation: Surface charge density means how much charge is stored in the unit surface area of a conductor. So, it’s unit will be=$$\frac{the \, unit \, of \, the \, charge}{the \, unit \, of \, area}$$. In SI the unit of charge is Coulomb and the unit of area is m2. Therefore the required unit will be C/m2.

#### 22. What number of electrons will flow in one minute through a conductor that carries 1 Ampere current?

a) 5.2*1020
b) 4.2*1020
c) 3.7*1020
d) 3.7*1019

Explanation: 1 Ampere means 1 Coulomb per second. So the number of electrons flow per second is $$(\frac {1}{1.602*10^{-19}})$$. Therefore number of electron flow in one minute =$$\frac {1}{1.602*10^{-19}}$$*60 =3.7*1020.The number will be 60 times more if we have to calculate the number of electron flow in an hour.

#### 23. What is the dimension of volume charge density?

a) [MLAT-2]
b) [M0 L-3 A T]
c) [M L-3 A T]
d) [M L-2 A T]

Explanation: Volume charge density = $$\frac {charge}{volume}=\frac {current*time}{volume}=\frac {A*T}{L^3}$$=[M0 A T L-3]. But in case of surface charge density, the dimension will be [M0 L-2 A T] because surface charge density means an electric charge in a unit area of the surface.

#### 24. Which one of the following is a safe place during lightning?

a) Under a tree
b) Under a light post
c) House with lightning arrester
d) High wall

Explanation: Lightning arrester arrests lightning and allows a safe path of electricity to ground. Thus it is a safe place inside a house that has a lightning arrester on the top of it. Else, electricity finds a high tower or tree or wall and travels through them to ground. Therefore these are not safe places to take shelter during lightning.

#### 25. What should be the shape of a conductor that can hold a charge for long?

a) Cubical
b) Conical
c) Sharp-edged
d) Spherical

Explanation: Sphere has uniform charge distribution over its entire surface. It doesn’t have any sharp edges hence very little chance of charge accumulation at those edges and hence very little chance of discharge of stored charge.

#### 26. A lightning arrester must have the following property.

a) Discontinuity
b) Poor conductivity
c) Needle end
d) Low melting point

Explanation: Needle end can arrest the lightning easily. Besides, the device must provide a continuous path to electricity so that current passes to ground. It must have a high melting point else it will meltdown due to the heat generated during carrying lightning current.

#### 27. Earth is the source of __________

a) An infinite positive and negative charge
b) Positive charge
c) Negative charge
d) Zero charge

Explanation: Earth can be considered as an infinite source of positive and negative charges. This can be justified by the fact that if we connect any positive or negatively charged body to the ground, all of its charges will go to earth.

#### 28. Which one is not the property of charge?

b) Charge is conserved
c) Quantization of charge
d) A charge is self-destructive

Explanation: Electric charge possesses the properties of quantization, conservation of charge. It cannot be destroyed i.e. it is not self-destructive.

#### 29. Coulomb’s Law is valid for ______

a) Only point charge
b) For both point charge and distributed charge
c) Only distributed charges
d) Neither distributed nor point charge

Explanation: Coulomb’s Law explains the force between two point charges only. A distributed charge can be considered as the sum of infinite point charges and thus the force between two distributed charge systems can be explained.

#### 30. Which one of the following is similar between electrostatic force and gravitational force?

a) Force can be attractive or repulsive
b) The force depends on the medium between the bodies
c) Both the forces are strong forces
d) Force is inversely proportional to the distance between the bodies