Tag: properties of charge

Questions Related to properties of charge

Charge separation can be affected by

physics static electricity properties of charges charge properties of charge

  1. contact

  2. pressure

  3. heat

  4. charge

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Correct Option: A,D
Explanation:
Charge separation can be affected by -
(a) Contact
(b) Charge
Because contact of force will be affected for the charge separation and charge accumulation will be the affected of charge separation pressure and heat also.

During charge separation, there is a

physics static electricity properties of charges charge properties of charge

  1. creation of charge

  2. creation of energy

  3. creation of charged particles

  4. creation of neutrons

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Correct Option: C
Explanation:

Charge separation is the process of exciting an electron in an atom to a higher energy level and then making it leave the atom to a hereby electron acceptor thus creating charged particle.

A metal sphere has a charge of $- 6 \mu C$. When $5 \times 10^{12} $ electrons are removed from the sphere, what would be net charge on it?

physics static electricity properties of charges charge properties of charge

  1. $-6.8 \mu C$

  2. $6.8 \mu C$

  3. $5.2 \mu C$

  4. $-5.2 \mu C$

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Correct Option: D
Explanation:

Charge removed=$-e\times n=-1.6\times 10^{-19}\times 5\times 10^{12}=-8\times 10^{-7}=-0.8\mu C$


Hence, charge on sphere=$-6-(-0.8)=-5.2\mu C$

Answer-(D)

Only the integral number of electrons which is transferred from one body to another, i.e. $\pm ne$. This is represented as

physics static electricity properties of charges charge properties of charge

  1. Superposition of charge

  2. Quantisation of charge

  3. Conservation of charge

  4. Addition of charge

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Correct Option: B
Explanation:

The transfer of electrons from one body to other leads to charging of bodies. It is found that charge on any body is always equal to integral multiple of charge on electron. This property of charge is known as Quantisation of electric charge according to which, $Q=ne$
$Q=$ total charge transferred
$n=$ number of electrons transferred
$e=$ charge on one electron
$n=1, \pm 2.....$ and so on.

A copper slab of mass $2 g$ contains $2 \times 10^{22}$ atoms. The charge on the nucleus of each atom is $29 e$. What fraction of the electrons must be removed from the sphere to give it a charge of $+2\mu C$? 

physics static electricity properties of charges charge properties of charge

  1. $58 \times 10^{22}$

  2. $1.25 \times 10^{13}$

  3. $2.16 \times 10^{11}$

  4. $2.16 \times 10^{-11}$

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Correct Option: D
Explanation:
Given a mass of copper slab $=2\, g$ contains $2\times 10^{22}$ atoms.
Charge on nucleus of each atom $=29e$
We have to find the fraction of electrons that must be removed from sphere to give it $+2\mu C$ charge.
We solve it as follows:
Total number of electrons in sphere $=29\times 2\times 10^{22}$
Number of electrons $=\dfrac qe$
$=\dfrac{2\times 10^{-6}}{1.6\times 10^{-19}}$
$=1.25\times 10^{13}$
Fraction of electrons removed $=\dfrac{1.25\times 10^{13}}{Total\; number \; of \;electrons \; in\; sphere}$
$=\dfrac{1.25\times 10^{13}}{29\times 2\times 10^{22}}$
$=2.16\times 10^{-11}$

Which of the following charges is/are impossible?

physics static electricity properties of charges charge properties of charge

  1. $4.8 \times 10^{-18}C$

  2. $5.8 \times 10^{-18}C$

  3. $12.8 \times 10^{-18}C$

  4. $20.8 \times 10^{-18}C$

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Correct Option: B
Explanation:
From $Q=ne$,
where $Q =$ total charge
$n=$ number of electrons
$e=$ charge on one electron 
So, only that charge is possible for which charge is whole multiple of $1.6\times 10^{-19}$ (i.e, charge on one electron).
We can see that multiplying $1.6\times 10^{-19}$ with $30$ gives $A$
Multiplying $1.6\times 10^{-19}$ with $80$ gives $C$
 Multiplying $1.6\times 10^{-19}$ with $130$ gives $D$
We can see that a, c and d are multiple of charge $1.6\times 10^{-19}\:C$.
Only $5.8\times 10^{-18}\: C$ given in B) option is not a multiple of $1.6\times 10^{-19}\:C$. 

Charge can be a multiple of $e$, i.e. $ne$. Which of the following can be a value of $n$?

physics static electricity properties of charges charge properties of charge

  1. 27

  2. 1.5

  3. 30.5

  4. 0.99999

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Correct Option: A
Explanation:

Charge has to be an integral multiple of electronic charge e.

If a conductor has $10^8$ number of electrons , then the total charge of the conductor is:

physics static electricity properties of charges charge properties of charge

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

  2. $-1.6 \times 10^{-19}$ C

  3. $+1.6 \times 10^{-11}$ C

  4. $-1.6 \times 10^{-11}$ C

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Correct Option: D
Explanation:

Any charge exists in discrete lumps or packets of a certain minimum charge e where e is the charge of an electron. According to quantization of charge, the charge on a body can be only an integral multiple of charge on the electron i.e., $q = ne$ where n = 1, 2, 3 and $e=1.6\times { 10 }^{ -19 }$ C.

So, for the given case, $q=10^8 \times (-1.6 \times 10^{-19})$ C$=-1.6 \times 10^{-11}$ C.

When a glass rod is rubbed against silk.

physics static electricity properties of charges charge properties of charge

  1. Glass rod loses electrons and becomes positively charged

  2. Silk loses electrons and becomes positively charged

  3. Glass rod losses electrons and becomes negatively charged

  4. Silk loses electrons and becomes negatively charged

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Correct Option: A
Explanation:

 Due to rubbing, heat is generated which supplies energy for removal of electrons. As the work function of the glass rod is smaller than the silk cloth, it easily loses electrons to the silk cloth.

How many electronic charges form 1 coulomb?

physics static electricity properties of charges charge properties of charge

  1. $9.1\times 10^{-31}$

  2. $1.6\times 10^{18}$

  3. $62.5\times 10^{17}$

  4. $1.76\times 10^{11}$

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Correct Option: C
Explanation:

$q=ne$
$\therefore n=\dfrac {q}{e}$
Given $q=1C$
$e=-1.6\times 10^{-19}C$
$n=\dfrac {1C}{1.6\times 10^{-19}}$
$6.25\times 10^{18}$ or $62.5\times 10^{17}$