1. Imagine a figure showing a square of side 10 cm with four charges placed at its corners. O is the centre of the square. Where, Four point charges qA= 2 µC, qB = -5 µC, qC = 2 µC, and qD = -5 µC are located at the corners of a square ABCD of side 10 cm. (Sides) AB = BC = CD = AD = 10 cm (Diagonals) ARead more

    Imagine a figure showing a square of side 10 cm with four charges placed at its corners. O is the centre of the square.

    Where, Four point charges qA= 2 µC, qB = -5 µC, qC = 2 µC, and qD = -5 µC are located at the corners of a square ABCD of side 10 cm.

    (Sides) AB = BC = CD = AD = 10 cm

    (Diagonals) AC = BD = 10√ 2 cm

    AO = OC = DO = OB = 5√ 2 cm A charge of amount lµC is placed at point O.

    Force of repulsion between charges placed at corner A and centre O is equal in magnitude but opposite in direction relative to the force of repulsion between the charges placed at corner C and centre O. Hence, they will cancel each other. Similarly, force of attraction between charges placed at corner B and centre O is equal in magnitude but opposite in direction relative to the force of attraction between the charges placed at corner D and centre O. Hence, they will also cancel each other. Therefore, net force caused by the four charges placed at the corner of the square on 1 µC charge at centre O is zero.

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  2. When two different objects of different nature are rubbed together it charges both the the objects  but one of it gets charged positive and and the other one is charged with an equal negative charge. Rubbing produces charges of equal magnitude but of opposite nature on the two bodies because chargesRead more

    When two different objects of different nature are rubbed together it charges both the the objects  but one of it gets charged positive and and the other one is charged with an equal negative charge. Rubbing produces charges of equal magnitude but of opposite nature on the two bodies because charges are created in pairs. This phenomenon of charging is called charging by friction. The net charge on the system of two rubbed bodies is zero. This is because equal amount of opposite charges annihilate each other. When a glass rod is rubbed with a silk cloth, opposite natured charges appear on both the bodies. This phenomenon is in consistence with the law of conservation of energy. A similar phenomenon is observed with many other pairs of bodies.

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  3. (a) .Electric charge of a body is quantized. This means that only integral (1,2... n) number of electrons can be transferred from one body to the other. Charges are not transferred in fraction. Hence, a body possesses total charge only in integral multiples of electric charge. (b) .In macroscopic orRead more

    • (a) .Electric charge of a body is quantized. This means that only integral (1,2… n) number of electrons can be transferred from one body to the other. Charges are not transferred in fraction. Hence, a body possesses total charge only in integral multiples of electric charge.
    • (b) .In macroscopic or large scale charges, the charges used are huge as compared to the magnitude of electric charge. Hence, quantization of electric charge is of no use on macroscopic scale. Therefore, it is ignored and it is considered that electric charge is continuous.
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  4. The given ratio is ke2 /G memp Where, G = Gravitational constant. Its unit is Nm2 kg-2 me and mp = Masses of electron and proton and their unit is kg. e=Electric charge and its unit is C. k =1 /4πε0and its unit  Nm2C-2. Therefore, unit of the given ratio ke2/Gmemp= [Nm2C-2][ C-2]/[Nm2kg-2][ kg] [ kgRead more

    The given ratio is ke2 /G memp

    Where, G = Gravitational constant. Its unit is Nm2 kg-2

    me and mp = Masses of electron and proton and their unit is kg.

    e=Electric charge and its unit is C.

    k =1 /4πε0and its unit  Nm2C-2.

    Therefore, unit of the given ratio

    ke2/Gmemp= [Nm2C-2][ C-2]/[Nm2kg-2][ kg] [ kg]

    =M0L0T0

    Hence, the given ratio is dimensionless.

    e = 1.6 x 10-19 C

    G = 6.67 x 10-11 N m2 kg’2

    me= 9.1 x 10-31 kg

    mp = 1.66 x 10-27kg

    Hence, the numerical value of the given ratio is

    ke2 / G memp=      9 x 109 x (1.6 x 10-19)2/ 6.67×10-11 x 9.1×10-31x 1.67×10-27

    ≈2.3 x 1039

    This is the ratio of electric force to the gravitational force between a proton and an electron, keeping distance between them constant.

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  5. Given the electrostatic force on a small sphere of charge 0.4 µC due to another small sphere of charge - 0.8 µC in air is 0.2 N. (a) What is the distance between the two spheres? (b) What is the force on the second sphere due to the first? (a) Electrostatic force on the first sphere, F = 0.2 N ChargRead more

    Given the electrostatic force on a small sphere of charge 0.4 µC due to another small sphere of charge – 0.8 µC in air is 0.2 N.

    (a) What is the distance between the two spheres?

    (b) What is the force on the second sphere due to the first?

    (a) Electrostatic force on the first sphere, F = 0.2 N Charge on this sphere, q1 = 0.4 µC = 0.4 X 10-6 C

    Charge on the second sphere,

    q2 = – 0.8 µC = – 0.8 x 10-6 C

    between the spheres is given by the relation

    Since Electrostatic force between two charges q1 and q2 separated by a distance of r is given by expression:

    F=1 /4πε0   x   q1q2/r²

    Where ε0   =Permittivity of free space and value of

    1 /4πε0 =9 X 109 Nm 2C²

     

    Therefore,

    r2= 1 /4πε0   x   (q1q2)/F

     

    r2= 9 x 109 x 0.4 x 10-6 x 8 x 10-6 /0.2

    r2= 144 x 10-4

    r=√(144 x 10-4)=(12×10-2)=0.12

    The distance between the two spheres is 0.12 m.

    (b) Both the spheres attract each other with the same force. Therefore, the force on the second sphere due to the first is 0.2 N.

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