Tag: charging and discharging

Questions Related to charging and discharging

On which factors from below does Coulomb's law(i.e. law of electrostatic attraction and repulsion) depends?

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. Magnitude of charges

  2. Distance between charges

  3. Both magnitude and distance between charges

  4. None of the above

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Correct Option: C
Explanation:

Coulomb's Law : $\dfrac{kq _1q _2}{r^2}$
It depends on both magnitude of charges and distance between them. 

Electric charges which are under the action of electric forces are known as :

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. Electrostatic

  2. Electric flux

  3. Electric field

  4. Electric field lines

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Correct Option: A
Explanation:

Electrostatic : when the charges are under action of electric forces. 

Electric flux : It is the measure of filed lines through a given area. 
Electric field  : the electric force per unit charge. 
Electric field lines : it measure the nature of charges, field lines is outward form positive charges and inner-ward for negative charges.

What does coulomb's law of attraction and repulsion states?

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. F is directly proportional to $q _1q _2$ and inversely proportional to $(r _{12})^2$

  2. F is directly proportional to $q _1q _2$ and inversely proportional to $(r _{12})$

  3. F is indirectly proportional to $q _1q _2$ and directly proportional to $(r _{12})^2$

  4. None

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Correct Option: A
Explanation:

The Coulomb law is the force between two charges $q _1$ and $q _2$ when the separation between them is $r _{12}$. 

Here , $F=\dfrac{kq _1q _2}{r _{12}^2}$
Thus, F is proportional to $q _1q _2$ and invewrsely proportional to $r _{12}^2$.

Which of the following represents Coulomb's constant?

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. $k\,=\,\frac{1}{4\times \pi \times e^0}$

  2. $k\,=\,1$ + ($4\times \pi \times e^0$)

  3. $k\,=\,1$ - ($4\times \pi \times e^0$)

  4. $k\,=\,1$ * ($4\times \pi \times e^0$)

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Correct Option: A
Explanation:

We know that Coulomb's force, $F=\frac{1}{4\pi \epsilon _0} \frac{q _1q _2}{r^2}$


The Coulomb constant will be  $k=\frac{1}{4\pi\epsilon _0}$

The value of the constant $k$ in coulomb's law is :

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. $9\times10^3$

  2. $9\times10^5$

  3. $9\times10^7$

  4. $9\times10^9$

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Correct Option: D
Explanation:

The Coulomb's constant, $k=\dfrac{1}{4\pi\epsilon _0}=\dfrac{1}{4\pi\times (8.85\times 10^{-12})}=9\times 10^9$

When we wear nylon dresses during winter then there is ______ current which gets produced due to contact with out body. Fill in the Blank.

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. Magnetic

  2. Electrostatic

  3. Potential

  4. kinetic

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Correct Option: B
Explanation:

When we wear nylon dresses during winter then there is electrostatic current which gets produced due to contact with out body.


Option B is correct.

When we rub our comb with hair and then take near to the paper pieces, all pieces get stuck to the comb. This happens due tyo which phenomena?

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. Electrostatic Induction

  2. Magnetic effect

  3. Potential effect

  4. Kinetic effect

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Correct Option: A
Explanation:

When negative charges is created in the comb by rubbing it with hair and pieces of paper are exposed to the electric field created by the charge, the part of paper closer to the comb will be positively charged due to electromagnetic induction, and the farther would be negatively charged, causing the paper to be attracted to the comb.

The force between two bodies having charges $5C$ and $10C$ separated by distance of $0.5 m$ in air is :

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. $18\times 10^{11}\ N$

  2. $9\times 10^{11}\ N$

  3. $9\times 10^{9}\ N$

  4. $18\times 10^{9}\ N$

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Correct Option: A
Explanation:

By Coulomb's law, the force between two charges is $F=k \dfrac{q _1q _2}{r^2}=(9\times 10^9)\times \dfrac{5\times 10}{(0.5)^2}=18\times 10^{11} N$

A closed switch has a resistance of :

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. zero ohm

  2. about $50$ ohms

  3. about $500$ ohms

  4. infinity

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Correct Option: A
Explanation:

A closed switch has a Zero resistance.


Option A is correct.

Which of the following materials has a negative temperature coefficient of resistance?

physics electric fields introduction to electrostatic force electric force charging and discharging

  1. Copper

  2. Aluminium

  3. Carbon

  4. brass

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Correct Option: C
Explanation:

Carbon has a negative temperature coefficient of resistance. 

Option C is correct.