1. Ans (a). Since diameter of the sphere, d = 4 m, therefore Radius of the sphere, r = 1.2 m Surface charge density, σ =80.0 µC/m2 = 80 x 10-6 C/m2 Total charge on the surface of the sphere, Q = Charge density x Surface area = σ x 4 π r2 = 80 x 10-6 x 4 x 3.14 x (1.2)2 = 1.447 x 10-3 C Therefore, the cRead more

    • Ans (a).

    Since diameter of the sphere, d = 4 m,

    therefore Radius of the sphere, r = 1.2 m

    Surface charge density, σ =80.0 µC/m2 = 80 x 10-6 C/m2

    Total charge on the surface of the sphere,

    Q = Charge density x Surface area = σ x 4 π r2 = 80 x 10-6 x 4 x 3.14 x (1.2)2 = 1.447 x 10-3 C Therefore, the charge on the sphere is 1.447 x 10-3 C.

    Ans (b).

    Total electric flux (ΦTotal ) leaving out the surface of a sphere containing net charge Q is given by the relation,

    ΦTotal =Q/ε

    Where, ε= Permittivity of free space = 8.854 x 10-12 N-1C2 m-2

    Q = 1.447 x 103C

    Therefore ΦTotal =Q/ε0 = ( 1.447 x 103)/(8.854 x 10-12 )

    = 1.63 x 108NC-1m2

    Therefore, the total electric flux leaving the surface of the sphere is 1.63 x 108 N C-1 m2.

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  2. Electric field intensity (E) at a distance (d) from the centre of a sphere containing net charge q is given by the relation, E= 1 /4πε0   x   q/d² Where, q = Net charge = 1.5 x 103 N/C d = Distance from the centre of sphere = 20 cm = 0.2 m ε0  = Permittivity of free space and 1 /4πε0 = 9 x109Nm2C⁻2Read more

    Electric field intensity (E) at a distance (d) from the centre of a sphere containing net charge q is given by the relation,

    E= 1 /4πε0   x   q/d²

    Where, q = Net charge = 1.5 x 103 N/C

    d = Distance from the centre of sphere = 20 cm = 0.2 m

    ε = Permittivity of free space and

    1 /4πε0 = 9 x109Nm2C⁻2

    Therefore,

    q = E(4πε0)d2 =

    =(1.5 x 10³) (0.2)2 / (9 x 109)

    6.67 x 10⁻9C =6.67 nC

    Therefore, the net charge on the sphere is 6.67 nC.

     

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  3. Ans (a). Electric flux, Φ = —1.0 x 103 N m2/C and radius of the Gaussian surface, r = 10.0 cm Electric flux piercing out through a surface depends on the net charge enclosed inside a body. It does not depend on the size of the body. If the radius of the Gaussian surface is doubled, then the flux pasRead more

    Ans (a).

    • Electric flux, Φ = —1.0 x 103 N m2/C and radius of the Gaussian surface, r = 10.0 cm Electric flux piercing out through a surface depends on the net charge enclosed inside a body. It does not depend on the size of the body. If the radius of the Gaussian surface is doubled, then the flux passing through the surface remains the same i.e., —103 N m2/C.
    • Ans (b).

    Electric flux is given by the relation

    Φ=q/ε0

    Where ε0 = Permittivity of free space = 8.854 x 10–12 N–1C2 m-2

     q = Net charge enclosed by the spherical surface = Φε0

    = -1.0 x 103 x 8.854 x 10–12 =-8.854 x 109C = -8.854 nC

    Therefore, the value of the point charge is -8.854 nC.

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  4. Net electric flux (ΦNet) through the cubic surface is given by ΦNet =q/ε0 Where, ε0 = Permittivity of free space = 8.854 x 10⁻12 N⁻1C2 m⁻2 q = Net charge contained inside the cube = 2.0 µC = 2 x 10⁻6 C Therefore ΦNet =(2 x 10⁻6)/8.854 x 10⁻12 =2.26 x 10⁵Nm2C⁻1 The net electric flux through the surfaRead more

    Net electric flux (ΦNet) through the cubic surface is given by

    ΦNet =q/ε0

    Where,

    ε0 = Permittivity of free space = 8.854 x 10⁻12 N⁻1C2 m⁻2

    q = Net charge contained inside the cube = 2.0 µC = 2 x 10⁻6 C

    Therefore ΦNet =(2 x 10⁻6)/8.854 x 10⁻12

    =2.26 x 10⁵Nm2C⁻1

    The net electric flux through the surface is 2.26 x 10⁵Nm2C⁻1

     

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  5. Refer Figure 1.34 Exercise 1.18 The square can be considered as one face of a cube of edge 10 cm with a centre where charge q is placed. According to Gauss’s theorem for a cube, total electric flux through all its six faces. ΦTotal = q/ε0  Hence, electric flux through one face of the cube i.e., throRead more

    Refer Figure 1.34 Exercise 1.18

    The square can be considered as one face of a cube of edge 10 cm with a centre where charge q is placed. According to Gauss’s theorem for a cube, total electric flux through all its six faces.

    ΦTotal = q/ε

    Hence, electric flux through one face of the cube i.e., through the square is

    Φ=ΦTotal /6 =1/6 x q/ε

    Where,

    ε0 = Permittivity of free space = 8.854 x 1012 N1C2 m-2

    q = 10 µ C = 10 x 10-6 C

    Therefore  Φ=1/6 x (10 x 10-6)/ 8.854 x 10-12

    = 1.88 x 105 N m2 C-1

    Therefore, electric flux through the square is 1.88 x 105 N m2 C-1

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