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CBSE Questions for Class 12 Medical Physics Electric Charges And Fields Quiz 15 - MCQExams.com

Two infinite linear charge are placed parallel at 0.1 m apart. It has density of 5 μ C/m,then the force per unit length of one of linear charges in N/m is;    
  • 2.5
  • 3.25
  • 4.5
  • 7.5
The electric field in a region is given by E=aˆi+bˆj. Here a and b are constants. Find the net flux passing through a square area of side l parallel to y-z plane:
  • al2
  • bl2
  • Zero
  • (a+b)l2
A charge Q is placed at the  centre of cube. The electric flux emerging from any one surface of the cube is .
  • Qε0
  • Q2ε0
  • Q4ε0
  • Q6ε0

Identify the wrong statement in the following. Coulomb's law correctly describes the electric force that 

  • Binds the electrons of an atom to its nucleus
  • Binds the protons and neutrons in the nucleus of an atom
  • Binds atoms together to form molecules
  • Binds atoms and molecules together to form solids
A charge QμC is placed at the center of a cube, the flux coming out from three face will be (in coulomb) :
  • Q6ε0×106
  • Q2ε0×106
  • 3Qε0×106
  • Q24ε0×106
A point charge  q  is placed at a point inside a hollow conducting sphere. Which of the following electric force pattern is correct?
A hemispherical surface (half of a spherical surface) of radius  R  is located in a uniform electric field  E  that is parallel to the hemisphere. What is the magnitude of the electric flux through the hemisphere surface ?
1542784_23d419138e2f4c4d88c2734640954853.png
  • 0
  • 4πR2E/3
  • 2πR2E
  • πR2E

A dipole of dipole moment ¯P=2ˆi3ˆj+4ˆk is placed at point A(2,3,1). The electric potential due to this dipole at the point B(4,1,0) is equal to ( All the parameters specified here are in S.I. units.)

  • 2×109Volts
  • 2×109Volts
  • 3×109Volts
  • 3×109Volts
In the given figure flux through surface  S1  is  ϕ1   &  through  S2  is  ϕ2.  Which is correct ?
1542916_8c403a9a8c3c4f1ab30c265c92f8595f.png
  • ϕ1=ϕ2
  • ϕ1>ϕ2
  • ϕ1<ϕ2
  • None of these
If +qcharge is placed inside any spherical surface then total flux coming out from whole surface will be -
  •  q×ϵ0
  • qϵ0
  • ϵ0q
  • q2ϵ0
A charge q is placed at one corner of a cube. The electrons flux through any of the three faces adjacent to the charge is zero. The flux through any one of the other three is
  • q/3ϵ0
  • q/6ϵ0
  • q/12ϵ0
  • q/24ϵ0
The surface density of charge on a very large flat metal plate is 2.25×109coul/m2. The intensity of electric field at a point at a distance 20 cm from the middle part of plate is 
  • 90πN/C
  • 100πN/C
  • 45πN/C
  • 81πN/C
A long cylindrical conductor, of radius  5mm  and placed in a medium of permittivity  55.55pF/m,  has surface charge density of  2μC/m2.  The magnitude of the electric intensity at a point  2m  from its axis is nearly
  • 9N/C
  • 90N/C
  • 1.111×102N/C
  • 1.111×102N/C
The electric flux ϕ through a hemisphere surface of radius R, placed in a uniform electric field of intensity E parallel to the axis of its circular plane is:
  • 2πRE
  • 2πR2E
  • πR2E
  • πR3E
When a 10μC charge is enclosed by a closed surface, the flux passing through the surface is ϕ. Now another 5μC charge is placed inside the same closed surface, then the flux passing through the surface is__________
  • 2ϕ
  • ϕ/2
  • ϕ
  • Zero
Given a uniform electric field E=5×103ˆi N/C, find the flux of this field through a square of 10 cm on a side whose plane is parallel to the yz plane. What would be the flux through the square if the plane makes 30 angle with the x-axis.
  • 23.3N/Cm2
  • 25N/Cm2
  • 33.3N/Cm2
  • 43.3N/Cm2
 A positive charge q is enclosed by a Gaussian spherical surface of radius 'a' . If its radius is increased to 4a then the net outwards flux will
  • Become four time
  • Become two times
  • Become sixten times
  • Remain same
A point charge A of charge +4μC and another point charge B of charge 1μC are placed in air at a distance 1 meter apart . then the distance of the point on the line joining the charges and from the charge B , where the resultant electric field is zero , is ( in meter)
  • 1.5
  • 0.5
  • 1
  • 2
A wire of linear charge density  λ  passes through a cuboid of length  l,  breadth  b  and height  h  in such a manner that flux through the cuboid is maximum. The position of wire is now changed, so that the flux through the cuboid is minimum.  l>b>h,  then the ratio of maximum flux to minimum flux will be
  • 12+b2+h2h
  • l2+b2h
  • hl2+b2
  • ll2+b2+h2
Two charges +3.2×1019and3.2×1019C  placed 2.4˚A apart form an electric dipole.It is placed in a uniform electric field of intensity 4×105V/m. The electric dipole moment is
  • 15.36×1029Cm
  • 15.36×1019Cm
  • 7.68×1029Cm
  • 7.68×1019Cm
Two identical metal spheres possess +60C and 20C of charges. They are brought in contact and then separated by 10cm. The force between them 
  • 36×1013N
  • 36×1014N
  • 36×1012N
  • 3.6×1012N
A current I flows through a cylindrical rod of uniform cross-section area A and resistivity ρ. The electric flux through the shaded cross-section of rod as shown in figure is :
1546553_4134cbf4bf5543c88cd718b7a7ac4abf.png
  • 2pI
  • pI
  • pIA
  • pAI
The  electric flux through the  surface 
1605888_a515aef0e0e1451b85295f9477d0fcc3.png
  • in Fig. (iv) is the largest
  • in Fig. (iii) is the least
  • in Fig. (ii) is same as Fig. (iii) but is smaller then Fig (iv)
  • is the same for all the figures
In a region the electric potential is given by V=2x+2y3z obtain the expression for electric field.
  • 2ˆi2ˆj+3ˆk
  • 3ˆi+4ˆj2ˆk
  • 2ˆi2ˆj3ˆk
  • None of these
The force of intraction of two dipoles, if the two dipole moments are parallel to each other and placed at a distance x apart.
1704370_4fef066af5d041d7ae9dc2e6f3ac4d85.png
  • 3p1p24πϵ0x4
  • p1p24πϵ0x4
  • p1p24πϵ0x4
  • p1p23πϵ0x4
Mark correct option:
Electrostatic experiment is
  • Affected on the humid day
  • Not affected on humid day
  • Independent of medium
  • None of the above
A long thread carrying a uniform charge λ per unit length has the configuration shown in the figure. An element of charge q is cut from the thread. The cutting portion is shown as small gap (AB). The electric field at the point O is
1704042_00bdb1e87e1f468d8acc71f98bbc3501.png
  • Zero
  • q4πε0R2
  • q2πε0R2
  • None of these
The electric lines of force are represented by the equation x2+y2=1. A unit positive charge initially at rest at point (1,0) will move.
  • along the circular line of force
  • at right angles to circular line of force
  • along equidistant parallel lines of force
  • at right angles to equidistant parallel lines of force
A charged particle q is placed at the centre O of a cube of length L(A B C D E F G H). Another same charge q is placed at a distance L from O. Then the electric flux through ABCD.
1592051_37d59cae2a744c72aaa289ff377fb2d7.png
  • q/6πϵ0L
  • Zero
  • q/2πϵ0L
  • q/3πϵ0L
In a region, an electric field E=E0ˆi is present. The potential of points A(a,0,0),B(0,b,0),C(0,0,c) and D(a,0,0) and VA,VB,VC and VD respectively, then
  • VA=VB=VC=VD
  • VB=VC
  • VD<VB<VA
  • None of these
Electric field in a plane varies like (2xˆi+2yˆj)N/C. If potential at infinity is taken as zero, potential at x=2m,y=2m is
  • 8 V
  • 8 V
  • Zero
  • Infinity
Six negative equal charges are placed at the vertices of a regular hexagon. 6q charge is placed at the centre of the hexagon. The electric dipole moment of the system is
1704373_ba4e84f5a6fd4ddf8fee52fe9a15626b.png
  • Zero
  • 6qa
  • 3qa
  • None of the above
Electric dipole moment of combination shown in the figure, is
1704372_97273cb55953432b8e1c140cf0642690.PNG
  • qa+qa2+qa
  • 22qa
  • 2qa
  • (2+1)qa
Each of the following figures shows electric field vectors at two points A and Bin an electric field. In which figure or figures can the illustrated field be created by a single point charge?
Electric charges q,q,2q are placed at the corners of an equilateral triangle ABC of sides l . The magnitude of electric dipole moment of the system is 
  • ql
  • 2ql
  • 3ql
  • 4ql
0:0:2


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