Tag: electric fields

Questions Related to electric fields

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.

An electric filament bulb can be worked from

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

  1. DC supply only

  2. AC supply only

  3. Battery supply only

  4. All above

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Correct Option: D
Explanation:

An electric filament bulb can be worked from

1. AC Current.
2. DC Current.
3. Battery current.

Option D is correct.

The filament of an electric bulb is made of :

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

  1. Carbon

  2. Aluminium

  3. Tungsten

  4. Nickel

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Correct Option: C
Explanation:

The filament of an electric bulb is made of tungsten because it has some amazing properties including the highest melting point $(3422^oC )$, lowest vapor pressure, and greatest tensile strength out of all the metals. Because of these It can reach high temperature before melting.  

Which is the best conductor of electricity?

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

  1. Iron

  2. Silver

  3. Copper

  4. Carbon

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Correct Option: B
Explanation:

Silver is a best conductor of electricity because it contains maximum number of free electron.Also the resistance of silver is very low.


Option B is correct.