Tag: static electricity

Questions Related to static electricity

A polythene piece rubbed with wool is found to have a negative charge of $3.6\times 10^{-7}C.$ Calculate the number of electrons transferred from wool to polythene:

physics static electricity explaining static electricity charging by induction electric charges and fields

  1. $6.25\times 10^{18}$

  2. $2.25\times 10^{12}$

  3. $2.05\times 10^{-18}$

  4. $2.18\times 10^{10}$

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Correct Option: B
Explanation:

$n=\dfrac {q}{e}=\dfrac {-3.6\times 10^{-7}C}{-1.6\times 10^{-19}C}$

$=2.25\times 10^{12}$
$\therefore 2.25\times 10^{12}$ electrons are transferred from wool to polythene.

In induction the charge induced in the near surface of a dielectric is:

physics static electricity explaining static electricity charging by induction electric charges and fields

  1. equal and similar

  2. greater and dissimilar

  3. lesser and dissimilar

  4. equal and dissimilar

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Correct Option: C
Explanation:

In induction, the charge induced in the near surface of a dielectric is lesser and dissimilar.

A sure test of electrification is:

physics static electricity explaining static electricity charging by induction electric charges and fields

  1. attraction

  2. repulsion

  3. friction

  4. induction

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Correct Option: B
Explanation:

Repulsion is the sure test of electrification.
Note: If two bodies are electrified (i.e., charged they can either attract or repel). If they are:
(a) attracted: this is not only possible by electrification but can also be due to the attraction of an uncharged body with charged body.
(b) repulsion: repulsion is possible only when both objects are charged oppositely.

When a glass rod is rubbed with silk, both become charged due to:

physics static electricity explaining static electricity charging by induction electric charges and fields

  1. migration of protons

  2. exchange of electrons and protons

  3. migration of electrons

  4. migration of neutrons

Show answer
Correct Option: C
Explanation:

When a glass rod is rubbed with silk cloth glass rod becomes positively charges while silk cloth becomes negatively charged. This is due to transfer or migration of electrons from glass rod to silk cloth.

A glass rod when rubbed with silk cloth acquires a charge $1.6 \times 10^{-13}  C$. What is the charge on the silk cloth?

physics static electricity explaining static electricity charging by induction electric charges and fields

  1. $-1.6 \times 10^{-19} C$

  2. $1.6 \times 10^{-13} C$

  3. $-1.6 \times 10^{-13} C$

  4. $1.6 \times 10^{-19} C$

Show answer
Correct Option: C
Explanation:

When a glass rod is rubbed with silk, both gets electrified due to charging by friction. Given, glass rod acquires positive charge $=1.6\times 10^{-31}\, C$. So silk acquires equal and opposite charge as that on glass rod. Hence the answer is $-1.6\times 10^{-13}\, C$.

A gold coin has a charge of $+10^{-4} C$. The number of electrons removed from it is:

physics static electricity properties of charges charge properties of charge

  1. $10^6$

  2. $625 \times 10^{12}$

  3. $1.6 \times 10^{-25}$

  4. $1.6 \times 10^{13}$

Show answer
Correct Option: B
Explanation:

The total charge of electrons removed from the coin would be equal to the positive charge acquired by the coin.

Thus, $10^{-4}C=n\times 1.6\times 10^{-19}C$
$\implies n=625\times 10^{12}$

A parallel late condenser consists of two circular plate each of radius $8cm$ separated by a distance of $2mm$. It is charged by an external source, with a constant charging current of $0.15$ A. The displacement.curcent is

physics static electricity properties of charges charge properties of charge

  1. $0.10A$

  2. $0.15A$

  3. $0.20A$

  4. $0.30A$

Show answer
Correct Option: A

Choose best option about cavity for a charged metallic sphere: 

physics static electricity properties of charges charge properties of charge

  1. Net field inside the cavity is zero

  2. Net field inside the metal is non-zero constant

  3. Potential inside the metal is constant

  4. Potential outside metal is constant

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Correct Option: A
Explanation:

Inside the cavity of charged measure sphere net electric field is non zero constant.

$\therefore $ Option $A$ is correct.

Two charges 2$\mathrm { uC }$ and 1$\mathrm { \mu }C$ are placed at adistance of 10$\mathrm { cm }$ . The position of the third charge from2$\mu \mathrm { C }$ between them so that it does not experience any force

physics static electricity properties of charges charge properties of charge

  1. $7cm$

  2. $2cm$

  3. $5.858cm$

  4. $8cm$

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Correct Option: C

An infinite number of charges each equal to q coulomb are placed along x-axis at x 1, x = 2, x= 8. so on the potential and electric field at x =0 due to this arrangement is

physics static electricity properties of charges charge properties of charge

  1. $\dfrac { q } { 2 \pi \varepsilon _ { 0 } } , \dfrac { 3 q } { 4 \pi \varepsilon _ { 0 } }$

  2. $\dfrac { q } { 2 \pi \varepsilon _ { 0 } } \cdot \frac { q } { 3 \pi \varepsilon _ { 0 } }$

  3. $\dfrac { 2 q } { \pi \varepsilon _ { 0 } } , \dfrac { q } { 3 \pi \varepsilon _ { 0 } }$

  4. $\dfrac { q \varepsilon _ { 0 } } { \pi 2 } , \dfrac { q E _ { 0 } } { 3 \pi }$

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Correct Option: B