Tag: properties of charge

Questions Related to properties of charge

The electronic charge 'e' is the ............ possible charge.

physics static electricity properties of charges charge properties of charge

  1. maximum

  2. minimum

  3. avarage

  4. total

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Correct Option: B
Explanation:

Charge is an integral multiple of e, minimum charge possible is equal to e which is $1.6 \times 10^{-19}$ C.Hence correct answer is option B.

If the number of electric lines of force emerging out of a closed surface is 1000, then the charge enclosed by the surface is

physics static electricity properties of charges charge properties of charge

  1. $8.854 \times {10^{ - 9}}C$

  2. $8.854 \times {10^{ - 4}}C$

  3. $8.854 \times {10^{ - 1}}C$

  4. $8.854\,C$

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Correct Option: A
Explanation:

Given that $\phi $, no. of field lines $=1000$

From gauss law,
$\phi =\dfrac { { Q } _{ inc } }{ { \varepsilon  } _{ 0 } } $
$\therefore \quad 1000=\dfrac { { Q } _{ inc } }{ 8.85\times { 10 }^{ -12 } } $
$\Rightarrow \quad { Q } _{ inc }=8.85\times { 10 }^{ -12 }\times 1000$
                   $=8.854\times { 10 }^{ -9 }C$

$\therefore $  Option (A) is the correct answer.

Two insulated charged spheres of radii $20cm$ and $25cm$ respectively and having equal charge $q$ are connected by a copper wire and then they are separated

physics static electricity properties of charges charge properties of charge

  1. Both the spheres will have same charge $q$

  2. The charge on $20cm$ sphere will be greater than on the $25cm$ sphere

  3. The charge on $25cm$ sphere will be greater than on the $20cm$ sphere

  4. Both have same charge density 

Show answer
Correct Option: B
Explanation:

After redistribution, charges on them will be different, but they will acquire common potential i.e.

$k\frac{Q _1}{r _1}=k\frac{Q _2}{r _2}\Rightarrow\frac{Q _1}{Q _2}=\frac{r _1}{r _2}$
As,
$\sigma=\frac{Q}{4\pi r^2}$
$\frac{\sigma _1}{\sigma _2}=\frac{Q _1}{Q _2}\times \frac{r _2^2}{r _1^2}\Rightarrow \frac{\sigma _1}{\sigma _2}=\frac{r _2}{r _1}$
$\sigma \propto \frac{1}{r}$ i.e. surface charge density on smaller sphere will be more.

There are $4\times { 10 }^{ 23 }$ atoms in a metal sphere. If one electron is removed from $0.1\%$ of atoms, what will be the charge on the sphere?

physics static electricity properties of charges charge properties of charge

  1. $-6.4C$

  2. $64C$

  3. $0.64C$

  4. $-64C$

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Correct Option: D
Explanation:
Given, 

$n=4\times 10^{23}\times 0.1$%

$n=4\times 10^{23}\times \dfrac{0.1}{100}=4\times 10^{20}$

$e=1.6\times 10^{-19}C$

The charge is quantised, $q=ne$

$q=4\times 10^{20}\times 1.6\times 10^{-19}=64C$

The electron is negative charge particle.

So,$q=-64C$

The correct option is D.

The density of field lines surrounding any given object reveal information about the

physics static electricity properties of charges charge properties of charge

  1. the nature of charge on the source charge.

  2. the quantity of charge on the source charge.

  3. both A and B

  4. it reveals no information

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Correct Option: B
Explanation:

The density of field lines shows the strength of field, and hence reveal the information about the magnitude of charge that is quantity of charge on the source.

The product of potential difference and charge is measured in 

physics static electricity properties of charges charge properties of charge

  1. colulomb

  2. volt

  3. juole

  4. watt

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Correct Option: A

The energy acquired by a charge of $8 \times 10 ^ { - 19 } { C }$ when passed through a potential difference of $200\ volt$

physics static electricity properties of charges charge properties of charge

  1. $500 \mathrm { eV }$

  2. $1000 \mathrm { eV }$

  3. $1500 \mathrm { eV }$

  4. $2000 \mathrm { eV }$

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Correct Option: B
Explanation:

$\begin{array}{l} U=qV \ =8\times { 10^{ -19 } }\times 200J \ =\dfrac { { 8\times { { 10 }^{ -19 } }\times 200 } }{ { 1.6\times { { 10 }^{ -19 } } } } eV \ =1000ev \ Hence,\, the\, option\, B\, is\, the\, correct\, answer. \end{array}$

Two charges of equal magnitude and at a distance'r' exert a force $F$ on each other. If the charges are halved and distance between them is doubled, then the new force acting on each charge is

physics static electricity properties of charges charge properties of charge

  1. $F / 8$

  2. $F / 4$

  3. $4 F$

  4. $F / 16$

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Correct Option: D
Explanation:

Original force$,$

$F = k\dfrac{{q\,q}}{{{r^2}}}$
New force$,$
$F = k\dfrac{{\dfrac{q}{2}\,\dfrac{q}{2}}}{{{{\left( {2r} \right)}^2}}} = \dfrac{1}{{16}}F = \dfrac{F}{{16}}$
Hence,
option $(D)$ is correct answer. 

Mark the correct options : 

physics static electricity properties of charges charge properties of charge

  1. The total charge of the universe is constant.

  2. The total positive charge of the universe is constant.

  3. The total negative charge of the universe is constant.

  4. The total number of charged particles in the universe is constant.

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Correct Option: A
Explanation:

The law of conservation of charges states that electric charge can neither be created nor destroyed.
Hence the net quantity of electric charge of the universe is always conserved. 

$\displaystyle \frac {4}{25}$ Coulomb of charge contains .......... electrons

physics static electricity properties of charges charge properties of charge

  1. $10^{15}$

  2. $10^{18}$

  3. $10^{20}$

  4. None of these

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Correct Option: B
Explanation:

The formula for quantization of charge is given as q=ne.
where q is the amount of charge in Columbu's, n is the number of charges and e is the charge on the electron.
In this case, q=4/25 C
So, e = $1.6\times { 10 }^{ -19 }C$.
n can be calculated as n=q/e = $\frac { 4 }{ 25 } \times [\dfrac { 1 }{ 1.6\times { 10 }^{ -19 }C } ]\quad =\quad { 10 }^{ 18 }$ which is the number of electrons.
Hence, 4/25 Coulomb of charge contains ${ 10 }^{ 18 }$ electrons.