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 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 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 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:-
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:-
Monochromatic light of wavelength 589 nm is incident from air on a water surface. What are the wavelength, frequency and speed of

(a) reflected, and

(b) refracted light? Refractive index of water is 1.33. - Q:-
Two towers on top of two hills are 40 km apart. The line joining them passes 50 m above a hill halfway between the towers. What is the longest wavelength of radio waves, which can be sent between the towers without appreciable diffraction effects?

- Q:-
What is the

(a) momentum,

(b) speed, and

(c) de Broglie wavelength of an electron with kinetic energy of 120 eV.

- Q:-
A 12.5 eV electron beam is used to bombard gaseous hydrogen at room temperature. What series of wavelengths will be emitted?

- Q:-
A hydrogen atom initially in the ground level absorbs a photon, which excites it to the n = 4 level. Determine the wavelength and frequency of the photon.

- Q:-
An electron emitted by a heated cathode and accelerated through a potential difference of 2.0 kV, enters a region with uniform magnetic field of 0.15 T. Determine the trajectory of the electron if the field (a) is transverse to its initial velocity, (b) makes an angle of 30º with the initial velocity.

- Q:- A radio can tune in to any station in the 7.5 MHz to 12 MHz band. What is the corresponding wavelength band?
- Q:-
The work function of caesium metal is 2.14 eV. When light of frequency 6 ×10

^{14}Hz is incident on the metal surface, photoemission of electrons occurs. What is the(a) maximum kinetic energy of the emitted electrons,

(b) Stopping potential, and

(c) maximum speed of the emitted photoelectrons?

- Q:-
Suppose the spheres A and B in Exercise 1.12 have identical sizes. A third sphere of the same size but uncharged is brought in contact with the first, then brought in contact with the second, and finally removed from both. What is the new force of repulsion between A and B?

- 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.)

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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