Question 23

An infinite line charge produces a field of 9 × 10^{4} N/C at a distance of 2 cm. Calculate the linear charge density.

Answer

Electric field produced by the infinite line charges at a distance d having linear charge density λ is given by the relation,

Where,

d = 2 cm = 0.02 m

E = 9 × 10^{4} N/C

∈_{0} = Permittivity of free space

= 9 × 10^{9} N m^{2} C^{−2}

^{}

= 10 μC/m

Therefore, the linear charge density is 10 μC/m.

- Q:-
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? - 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 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 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 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 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 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:-
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 4.5 cm needle is placed 12 cm away from a convex mirror of focal length 15 cm. Give the location of the image and the magnification. Describe what happens as the needle is moved farther from the mirror.

- Q:-
What is the Brewster angle for air to glass transition? (Refractive index of glass = 1.5.)

- Q:-
**Let us list some of the factors, which could possibly influence the speed of wave propagation:**(i) Nature of the source.

(ii) Direction of propagation.

(iii) Motion of the source and/or observer.

(iv) Wave length.

(v) Intensity of the wave.

**On which of these factors, if any, does**(a) The speed of light in vacuum,

(b) The speed of light in a medium (say, glass or water), depend?

- Q:- In an n-type silicon, which of the following statement is true:

(a) Electrons are majority carriers and trivalent atoms are the dopants.

(b) Electrons are minority carriers and pentavalent atoms are the dopants.

(c) Holes are minority carriers and pentavalent atoms are the dopants.

(d) Holes are majority carriers and trivalent atoms are the dopants. - Q:-
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? - Q:-
(a) Two insulated charged copper spheres A and B have their centers separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is 6.5 × 10

^{−7}C? The radii of A and B are negligible compared to the distance of separation.(b) What is the force of repulsion if each sphere is charged double the above amount, and the distance between them is halved?

- Q:-
Three capacitors of capacitances 2 pF, 3 pF and 4 pF are connected in parallel.

(a) What is the total capacitance of the combination?

(b) Determine the charge on each capacitor if the combination is connected to a 100 V supply.

- Q:-
In an experiment on photoelectric effect, the slope of the cut-off voltage versus frequency of incident light is found to be 4.12 × 10

^{−15}V s. Calculate the value of Planck’s constant. - Q:-
What is the shortest wavelength present in the Paschen series of spectral lines?

- Q:-
An electric dipole with dipole moment 4 × 10

^{−9}C m is aligned at 30° with the direction of a uniform electric field of magnitude 5 × 10^{4}N C^{−1}. Calculate the magnitude of the torque acting on the dipole.

Kundan
2019-08-16 13:09:32

NCERT ans is wrong

physics Nerd
2019-07-26 19:42:18

0.1Î¼C/m

Aman verma
2019-04-30 00:53:22

Answer is 1*10^-7 Coloumb which is 0.1 micro coloumb but your answer is wrong as ncert also printed wrong!!!!!

Amal c Paulson
2019-03-27 07:15:19

Answer is wrong

Arif ahmad
2019-01-03 10:18:36

Answer is wrong

I am right
2018-06-16 14:05:01

Answer is correct 10uC/m = 10 x 10^-6 C/m

Sharan Kumar
2018-05-28 21:55:33

This answer is wrong The correct answer is 1.008Ã10^-6

Sapna
2018-05-26 03:11:26

Really helpful

Ritesh
2018-05-25 18:34:30

Sister answere sahi hi apne answeres ko micro coulomb me badalo

sweety priya
2017-08-21 09:51:46

hi your answer is wrong the correct answer is 10^-7. explanation :- ð¸ = ð /2ðð0ð â ð = 2ðð0ðð¸ ð=2*3.14*8.85*10^-12*9*10^4 ð=6.28*18*10^-2*10^4*8.85*10^-12 ð=1000.3*10^2*10^-12 ð=10^3*10^2*10^-12 ð=10^-7 so,the correct answer is 10^-7

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