Tag: physics

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Questions Related to physics

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

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

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

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 If the rod is then suddenly withdrawn, the charge left on the conductor will be

  1. positive

  2. negative

  3. zero

  4. not sure
Reveal answer Fill a bubble to check yourself
C Correct answer
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.
Multiple choice physics static electricity exchange of electrons methods used for charging electric charge

 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 ? 

  1. -4C

  2. +4C

  3. -1C

  4. +1C

  5. Zero
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $Q _{av}=\dfrac{-3+1}{2}=-1 C$

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

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 ?

  1. Charging by conduction

  2. Charging by induction

  3. Charging by friction

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

What is known as charging by induction method?

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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?

  1. Saran Wrap

  2. Nylon

  3. Both

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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?

  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.
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. charging by friction

  2. charging by contact

  3. charging by induction

  4. both A and C
Reveal answer Fill a bubble to check yourself
D Correct answer
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.