Tag: static electricity

Questions Related to static electricity

Fill in the blank.

$1$ Coulomb of charge contains_______number of electrons.

physics static electricity properties of charges charge properties of charge

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

  2. $3.125\times 10^{18}$

  3. $6.25\times 10^{12}$

  4. $3.125\times 10^{12}$

Show answer
Correct Option: A
Explanation:

As charge is quantized. 

Total charge, $Q = ne$
$1$ coulomb $=ne \implies$ $n$ $= \dfrac{1} {1\cdot6\times10^{-19}}$

 
 $n$ $=6\cdot25\times10^{18}$

A body has a total charge of $6.4\times  10^{-19}$coulomb. It is :

physics static electricity properties of charges charge properties of charge

  1. possible

  2. not possible

  3. may or may not be possible

  4. Data insufficient

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Correct Option: A
Explanation:

Total charge must be quantized i.e., it must be a multiple of charge of $e^-$ $=$ $1\cdot 6\times 10^{-19}C$
as $4\times (1\cdot 6\times 10^{-19})=6\cdot 4\times 10^{-19}$
this charge is possible ($4e^-$)

A body has a charge of $9.6 \times 10^{-20}$coulomb. It is :

physics static electricity properties of charges charge properties of charge

  1. possible

  2. not possible

  3. may (or) may not possible

  4. Data not sufficient

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Correct Option: B
Explanation:

We know that charge must be integral multiples of $1\cdot 6\times 10^{-19}C$ as charge of
one electron $=1\cdot 6\times 10^{-19}C$
We cannot get any charge less than $1\cdot 6\times 10^{-19}$  $\therefore$ we cannot get $9\cdot 6\times 10^{-20}C$

The charges from one body can be Transferred to another body but the total charge of a system ...........

physics static electricity properties of charges charge properties of charge

  1. remains Constant

  2. can change

  3. Will increase

  4. will decrease

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Correct Option: A
Explanation:

The charges from one body can be transferred to another body but the total charge of a system remains constant.

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. $8.854\,C$

Show answer
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. $-64C$

Show answer
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