Tag: methods used for charging

Questions Related to methods used for charging

A positive point charge $Q$ is brought near an isolated metal cube. Then :

physics static electricity exchange of electrons methods used for charging electric charge

  1. the cube becomes negatively charged

  2. the cube becomes positively charged

  3. the interior becomes positively charged and the surface becomes negatively charged

  4. the interior remains charge free and the surface gets nonuniform charge distribution

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Correct Option: D
Explanation:

The metal cube is a conductor. The charge inside the conductor is zero. So the interior remains charge free. As it is isolated metal so when positive charge is brought near it , surface charge will become non-uniform.

A positively charged rod is brought near an uncharged conductor. If the rod is then suddenly withdrawn, the charge left on the conductor will be

physics static electricity exchange of electrons methods used for charging electric charge

  1. positive

  2. negative

  3. zero

  4. not sure

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Correct Option: C
Explanation:
When a charged rod is brought near an uncharged conductor, it will attract its charges and induce an opposite charge on conductor.
As the charged rod removed, the attraction forces disappear so as the charge on conductor.

 A conducting wire is connected between two conducting spheres of equal size have a charge of -3C and +1C respectively. Find out the new charge on each sphere ? 

physics static electricity exchange of electrons methods used for charging electric charge

  1. -4C

  2. +4C

  3. -1C

  4. +1C

  5. Zero

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Correct Option: C
Explanation:

When the two spheres are connected by a wire, the charge will flow between them till the potential between them will be same. Thus, the charge on each sphere is the average charge i.e $Q _{av}=\dfrac{-3+1}{2}=-1 C$

When a charged aluminum plate is touched to a neutral metal sphere then neutral metal sphere gets charged up. This happens due to which method of charging ?

physics static electricity exchange of electrons methods used for charging electric charge

  1. Charging by conduction

  2. Charging by induction

  3. Charging by friction

  4. None

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Correct Option: A
Explanation:

When a charged aluminum plate is touched to a neutral metal sphere then neutral metal sphere gets charged up. This happens due to which method of charging. This happens due to charging by conduction method.


Option A is correct.

What is known as charging by induction method?

physics static electricity exchange of electrons methods used for charging electric charge

  1. charge created through influence of charged object and not by contact

  2. charge created through contact of charged object and not by influence

  3. charge not generated

  4. None

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Correct Option: A
Explanation:

When charging a conductor by induction, a charged object is brought close to but does not touch the conductor. In the end the conductor has charge of the opposite sign as the charge on the object.


Option A is correct.

Saran wrap has a larger electron affinity then Nylon. If Nylon is rubbed againest Saran wrap which would end up with the excess negative charge?

physics static electricity exchange of electrons methods used for charging electric charge

  1. Saran Wrap

  2. Nylon

  3. Both

  4. None

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Correct Option: A
Explanation:

Those with larger electron affinity will be more nagatively charged as it takes electrons from nylon.

Therefore, Saran wrap will get excess negative charge.

Option A is correct.

State whether given statement is True or False :

Charging by conduction includes contact of charged object with the neutral object.

physics static electricity exchange of electrons methods used for charging electric charge

  1. True

  2. False

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Correct Option: A
Explanation:

True.

Charging by conduction means charged object is in contact with neutral object.

Option A is correct.

A conducting sphere with radius 4.0 cm has a net positive charge on it. The sphere is then connected with a metal wire to a second, uncharged, sphere of radius 1.0 cm.
Which statement below BEST describes the flow of electrons when the metal wire connects the two spheres?

physics static electricity exchange of electrons methods used for charging electric charge

  1. Electrons flow from the 4.0-cm radius sphere to the 1.0-cm radius sphere, leaving the 4.0-cm radius sphere with a net charge of zero.

  2. Electrons flow from the 1.0-cm radius sphere to the 4.0-cm radius sphere, until both spheres have the same net positive charge.

  3. Electrons flow from the 4.0-cm radius sphere to the 1.0-cm radius sphere until both spheres have the same net positive charge.

  4. Electrons flow from the 1.0-cm radius sphere to the 4.0-cm radius sphere until the surfaces of both spheres are at the same electric potential.

  5. Electrons do not flow along the wire, because the system is already in equilibrium.

Show answer
Correct Option: A
Explanation:

Given a conducting sphere, radius $4\, cm$ has positive charge on it. This sphere is then connected to uncharged sphere of radius $1\, cm$. So, when the two spheres are connected through a metal wire, the entire charge flow from charged to uncharged sphere i.e, electrons flow from $4\, cm$ sphere to$1\, cm$ sphere, leaving $4\, cm$ radius sphere with net charge zero.

 Which of the following charging methods result in charging an object opposite to the charge on the object used to charge it?

physics static electricity exchange of electrons methods used for charging electric charge

  1. charging by friction

  2. charging by contact

  3. charging by induction

  4. both A and C

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Correct Option: D
Explanation:
When two electrically neutral objects are rubbed against each other, some of the electrons get transferred from surface of one object to the other and thus the two objects become electrically charged with opposite polarity. This process is known as charging by friction. 
When a charge $Q$ is brought near an uncharged conductor, the charge $Q$ induces a charge of opposite polarity on the facing surface of the conductor and the same polarity on the rearer surface. This process of inducing a charge on the conductor is known as induction.
Charging by contact induces charge of same polarity on the neutral conductor.
Thus charging by induction and charging by friction are the two methods which results in charging an object opposite to the charge on the object used to charge it.

A solid sphere of radius R has a charge Q distributed in its volume with a charge density, $\rho ={ kr }^{ a }$, where k and a are constants and r is the distance from its centre. If the electric field at $r=\dfrac { R }{ 2 } $ is $\dfrac { 1 }{ 8 } $ times that at r=R, then the value of a is 

physics static electricity exchange of electrons methods used for charging electric charge

  1. 2

  2. 4

  3. 6

  4. 7

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Correct Option: D