Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(3)

To use Gauss Law, we have to consider a Gaussian surface whose the given square is a part of.

Using Gauss Law, we can find flux through the Gaussian surface and then we can divide the flux through each square.

Imagine a case, when a point charge q is placed at the center of a cube of side L.

 Flux passing through cube=q/0

 By symmetry, flux passing through each square =q/60

 

When the charge is placed closer to the square face i.e. at L/2, flux passing through square face will be more.
         So:- q60<<q0

Difficulty Level:

  • 39%
  • 13%
  • 37%
  • 12%

A solid conducting sphere of radius a has a net positive charge 2Q. A conducting spherical shell of inner radius b and outer radius c is concentric with the solid sphere and has a net charge –Q. The surface charge density on the inner and outer surfaces of the spherical shell will be 

(1) 2Q4πb2,Q4πc2

(2) Q4πb2,Q4πc2

(3) 0,Q4πc2

(4) None of the above

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(1) Surface charge density (σ) =ChargeSurface area

So σinner=2Q4πb2 and σOuter=Q4πc2 

Difficulty Level:

  • 48%
  • 20%
  • 25%
  • 9%

A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by 

(1) 2πR2E

(2) πR2/E

(3) (πR2πR)/E 

(4) Zero

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(4) Flux through surface A φA=E×πR2 and φB=E×πR2

Flux through curved surface C =E.ds=Edscos90o = 0

∴ Total flux through cylinder =φA+φB+φC = 0

Difficulty Level:

  • 25%
  • 7%
  • 9%
  • 61%

An electric charge is placed at the centre of a cube of side α. The electric flux on one of its faces will be 

(1) q6ε0

(2) qε0a2

(3) q4πε0a2

(4) qε0 

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(1) By Gauss's theorem.

Imagine a case when a point charge q is placed at the centre of a cube of side L.

 Flux passing through cube=q/0

 By symmetry, flux passing through each square =q/60

 

 

Difficulty Level:

  • 81%
  • 5%
  • 7%
  • 9%

Total electric flux coming out of a unit positive charge put in air is 

(1) ε0

(2) ε01

(3) (4pε0)1

(4) 4πε0 

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(2)Total flux coming out from unit charge =E.ds=1ε0×1=ε01  

Difficulty Level:

  • 14%
  • 73%
  • 7%
  • 7%

A cube of side l is placed in a uniform field E, where E=Ei^. The net electric flux through the cube is

(1) Zero

(2) l2 E

(3) 4 l2 E

(4) 6 l2 E

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(1) As there is no charge residing inside the cube, hence net flux is zero.

Difficulty Level:

  • 68%
  • 11%
  • 7%
  • 15%

A charge q is placed at the centre of the open end of cylindrical vessel. The flux of the electric field through the surface of the vessel is 

(1) Zero

(2) qε0

(3) q2ε0

(4) 2qε0 

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(3) To apply Gauss's theorem it is essential that charge should be placed inside a closed surface. So imagine another similar cylindrical vessel above it as shown in figure (dotted).

Difficulty Level:

  • 40%
  • 19%
  • 39%
  • 3%

According to Gauss’ Theorem, electric field of an infinitely long straight wire is proportional to 

(1) r

(2) 1r2

(3) 1r3

(4) 1r

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(4) e=λ2πε0rE1r   

Difficulty Level:

  • 6%
  • 20%
  • 6%
  • 70%

Electric charge is uniformly distributed along a long straight wire of radius 1mm. The charge per cm length of the wire is Q coulomb. Another cylindrical surface of radius 50 cm and length 1m symmetrically encloses the wire as shown in the figure. The total electric flux passing through the cylindrical surface is 

(1) Qε0

(2) 100Qε0

(3) 10Q(πε0)

(4) 100Q(πε0)

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(2) Charge enclosed by cylindrical surface (length 100 cm) is Qenc = 100Q.

By applying Gauss's law φ=1ε0(Qenc.)=1ε0(100Q)

Difficulty Level:

  • 25%
  • 58%
  • 9%
  • 10%

The S.I. unit of electric flux is 

(1) Weber

(2) Newton per coulomb

(3) Volt × metre

(4) Joule per coulomb

Concept Videos :-

#22 | Electric Flux
#23 | Gauss Theorem
#24 | Charged Infinite Wire (Gauss Theorem)
#25 | Charged Infinite Sheet (Gauss Theorem)
#26 | Charged Thin Conducting Shell (Gauss Theorem)
#27 | Solid Non Conducting Sphere : Gauss Theorem
#28 | Solid Sphere With Cavity : Gauss Theorem
#29 | Early Model of Atom (Gauss Theorem)
#30 | EFI Inside a Metal (Gauss Theorem)
#31 | Faraday Cages (Gauss Theorem)

Concept Questions :-

(3) S.I. unit of electric flux is N×m2C=J×mC = volt × m.   

Difficulty Level:

  • 28%
  • 14%
  • 51%
  • 8%