Question 1

What is the force between two small charged spheres having charges of 2 x 10^{-7} C and 3 x 10^{-7} C placed 30 cm apart in air?

Answer

Repulsive force of magnitude 6 × 10^{ - 3} N

Charge on the first sphere, q_{1} = 2 × 10 ^{- 7 }C

Charge on the second sphere, q_{2} = 3 × 10^{ - 7} C

Distance between the spheres, r = 30 cm = 0.3 m

Electrostatic force between the spheres is given by the relation,

Where, ∈_{0} = Permittivity of free space

Hence, force between the two small charged spheres is 6 × 10^{ - 3} N. The charges are of same nature. Hence, force between them will be repulsive.

- Q:-
An infinite line charge produces a field of 9 × 10

^{4}N/C at a distance of 2 cm. Calculate the linear charge density. - Q:-
A polythene piece rubbed with wool is found to have a negative charge of 3 × 10

^{−7}C.(a) Estimate the number of electrons transferred (from which to which?)

(b) Is there a transfer of mass from wool to polythene?

- Q:-
A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10

^{-12}F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6? - Q:-
A 600 pF capacitor is charged by a 200 V supply. It is then disconnected from the supply and is connected to another uncharged 600 pF capacitor. How much electrostatic energy is lost in the process?

- Q:- A circular coil of wire consisting of 100 turns, each of radius 8.0 cm carries a current of 0.40 A. What is the magnitude of the magnetic field B at the centre of the coil?
- Q:-
A regular hexagon of side 10 cm has a charge 5 µC at each of its vertices. Calculate the potential at the centre of the hexagon.

- Q:-
A point charge +10 μC is a distance 5 cm directly above the centre of a square of side 10 cm, as shown in Fig. 1.34. What is the magnitude of the electric flux through the square? (Hint: Think of the square as one face of a cube with edge 10 cm.)

- Q:-
A point charge of 2.0 μC is at the centre of a cubic Gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?

- Q:-
A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5 × 10

^{3}N/C and points radially inward, what is the net charge on the sphere? - Q:-
A 12 pF capacitor is connected to a 50V battery. How much electrostatic energy is stored in the capacitor?

- Q:-
The plates of a parallel plate capacitor have an area of 90 cm

^{2}each and are separated by 2.5 mm. The capacitor is charged by connecting it to a 400 V supply.(a) How much electrostatic energy is stored by the capacitor?

(b) View this energy as stored in the electrostatic field between the plates, and obtain the energy per unit volume

*u*. Hence arrive at a relation between*u*and the magnitude of electric field*E*between the plates. - Q:-
Two long and parallel straight wires A and B carrying currents of 8.0 A and 5.0 A in the same direction are separated by a distance of 4.0 cm. Estimate the force on a 10 cm section of wire A.

- Q:-
A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1.5 × 10

^{3}N/C and points radially inward, what is the net charge on the sphere? - Q:-
Two point charges q

_{A}= 3 μC and q_{B}= −3 μC are located 20 cm apart in vacuum.(a) What is the electric field at the midpoint O of the line AB joining the two charges?

(b) If a negative test charge of magnitude 1.5 × 10

^{−9}C is placed at this point, what is the force experienced by the test charge? - Q:-
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?

- Q:-
A toroid has a core (non-ferromagnetic) of inner radius 25 cm and outer radius 26 cm, around which 3500 turns of a wire are wound. If the current in the wire is 11 A, what is the magnetic field (a) outside the toroid, (b) inside the core of the toroid, and (c) in the empty space surrounded by the toroid.

- Q:-
What is the magnitude of magnetic force per unit length on a wire carrying a current of 8 A and making an angle of 30º with the direction of a uniform magnetic field of 0.15 T?

- Q:-
Two tiny spheres carrying charges 1.5 μC and 2.5 μC are located 30 cm apart. Find the potential and electric field:

(a) at the mid-point of the line joining the two charges, and

(b) at a point 10 cm from this midpoint in a plane normal to the line and passing through the mid-point.

- Q:-
A circular coil of 20 turns and radius 10 cm is placed in a uniform magnetic field of 0.10 T normal to the plane of the coil. If the current in the coil is 5.0 A, what is the

(a) total torque on the coil,

(b) total force on the coil,

(c) average force on each electron in the coil due to the magnetic field?

(The coil is made of copper wire of cross-sectional area 10

^{-5}m^{2}, and the free electron density in copper is given to be about 10^{29}m^{-3}.) - Q:-
A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = 10

^{-12}F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6?

Shubham Mishra
2019-10-17 20:37:48

Super ,pure phyisics ka video hai toh mere ko link bhejein

Lalisa
2019-08-19 21:06:15

Very nice

Gayatri
2019-07-14 16:41:25

This answer is correctÃ¢ÂœÂ…Ã¢ÂœÂ”Ã¢ÂœÂ”Ã¢ÂœÂ…Ã¢Â˜Â‘Ã¢ÂœÂ…Ã¢ÂœÂ”Ã¢Â˜Â‘Ã¢ÂœÂ… thank you so many answers are posted sir and mamdam

Prince
2019-06-15 14:57:25

Answer na aabit hau yrrr 10 ke power me garbara jaite huk

Rahul
2019-06-02 19:13:13

.3*.3=0.09 so 0.09 se 9 ko divide krne par 100 ayega

Prashant Kumar
2019-05-17 07:58:01

6.033x10^-5 ye answer aayega.

Alokananda Bhowmik
2019-04-02 09:41:46

But the answer is perfect in nootan aur calculater bhi 10^-3 dikbha rahi hain.

Prabhakar Kumar Tiwari
2019-03-29 02:09:53

Wrong Answer Right Answer= 1Ã¢Â€Â¢8ÃƒÂ—10 ka power -3

Sahil
2019-03-28 21:36:04

I m getting 5.4 into ten to the power -4

Megha
2019-02-20 20:17:57

Heee -3 kese aya 5 ata hai am confused plz reply me fast ok how it come ....

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