# Search results

1. ### Solving an equation involving Coulomb's law

Thanks Mr. Charles Link. In the first solution i get the q12 -6*10-6q1 -16*10-12 = 0 and for second one i get q12 - 6*10-6q1-16*106 = 0. My question is why i get different powers for the term involving -16.
2. ### Solving an equation involving Coulomb's law

Homework Statement Hi Members, I have solved an equation involving Coulomb's law in two ways and have posted the images of the same. I get two types of equations. Please help me to find where i gone wrong? Homework Equations The Attempt at a Solution
3. ### Quantisation of Charge

Homework Statement Quantisation means charge always exist in integral multiples of magnitude of charge of electron and to put it mathematically we say q = ne, where n is an integer 1,2,3,4 ... -1,-2,-3,... etc. Numerous print and web materials say that charge cannot exist in fraction or...
4. ### Finding the magnitude and direction of current thro Kirchhoff law

Thank you gneill and rude man for your help.
5. ### Finding the magnitude and direction of current thro Kirchhoff law

Homework Statement Revered Members, Please go through my attachment. I have been asked to find the magnitude and direction of current through the 10 ohm resistor. The answer that is given in the book is 1/23 Ampere from A to B. But i solved as given in the attachment but i got the answer...
6. ### Factors on which conductivity depends

Homework Statement The conductivity of a material depends on a) Resistance(R) b) Area of cross section(A) c) Length(L) d) Resistivity(ρ) Homework Equations The Attempt at a Solution The formula for Resistivity is given by ρ = AR/L and Conductivity(σ) being the reciprocal of...
7. ### Probability of picking a ball randomly from a group of balls

Homework Statement From a bag containing 4 white and 6 black balls, 2 balls are drawn at random. If the balls are drawn one after the other, without replacement, find the probability that The first ball is white and the second ball is black Homework Equations The Attempt at a...
8. ### Frictional charging and weight of the body involved

Homework Statement If a body is charged by rubbing it, its weight a) may slightly increase of slightly decrease b) increases slightly c) decreases slightly d) remains constant Homework Equations The Attempt at a Solution I know weight is nothing but gravitational force...

Thanks TSnY.
10. ### Induced Current and Eddy Current

Homework Statement I want to know whether Eddy current and Induced Current are same? Homework Equations The Attempt at a Solution 1)When flux linked with a circuit changes, an emf is induced in the circuit and this emf is called induced emf and the current is called induced...
11. ### Electronics questions - help needed

Electronics questions -- help needed Homework Statement Revered members, I list below some of the questions asked in a competitive exam to test the proficiency of electronics. I request the members to give the answers. I have produced the answers which i have written, below each question. I...
12. ### Position and acceleration vector - parallel and perpendicular

Thanks gneill. But this is how the question appears in University Exam paper.
13. ### Position and acceleration vector - parallel and perpendicular

Position and acceleration vector -- parallel and perpendicular Homework Statement The motion of a particle is defined by the position vector r = A(Cos t + t Sin t) i + A(Sin t + t Cos t) j where t is expressed in seconds. Determine the values of t for which the position vector and...
14. ### Infractions and their expiry

Thanks for the reply. Now all the accumulated points expires, and then one receives a fresh infraction which has worth(!) of 3 points. Now , will it be 11 points or 3 points
15. ### Attractive nature of nuclear forces

"At a distance of 1.5 fermi, the nuclear force becomes maximum and remains attractive in nature. However, at a distance of 0.5 fermi, the nuclear force suddenly becomes repulsive. " Revered Members, Nuclear force is a short range force, so naturally when the distance between the nucleons...
16. ### Infractions and their expiry

Dear Members and moderators, If the infractions received by a member expires, whether he/she will be given the concession of three warnings again?
17. ### Tension in the string rope

Thanks a lot Spinnor. So nice of you in explaining the things so beautifully.
18. ### Capacitors in series homework

Capacitors are connected in series. So the effective capacitance is 1/Cs = 1/C + 1/2C + 1/3C = 11/6C Cs = 6C/11 Now substitute this value for C for the equation V = 11/6(Q/C) you ll get Q/C which is nothing but V or V1 Hope you got it now
19. ### Capacitors in series homework

I can't get you. Actually is 11/6 times the V
20. ### Capacitors in series homework

V = q/c so v = q/c + q/2c + q/3c q/c(1+1/2+1/3) q/c (11/6) hope this helps
21. ### Tension in the string rope

Homework Statement 1) A box of mass 42kg sits on the top of a ladder. Neglecting the weight of the ladder, find the tension in the rope. Assume the rope exerts horizontal forces on the ladder at each end. Homework Equations m1g – T = m1a The Attempt at a Solution T = m1g - m1a...
22. ### Resistance and Temperature in conductors and semiconductors

Homework Statement Revered Members, When we increase the temperature, resistance increases in conductors. But resistance decreases in semiconductors. Why? Help in this regard will be highly appreciated. Homework Equations The Attempt at a Solution Due to increase in temperature...
23. ### Nuclear Binding Energy

Revered Members, For Helium, Beryllium,Carbon,Oxygen and Neon, the Binding Energy per nucleon is more as evident from the sharp peaks observed in the graph plotted between BE and Mass number. These elements have equal number of protons and neutrons. When there is an inequality between proton...
24. ### Coulomb's law in vector form

Thanks again. If charges are opposite, then attractive force exists. Will the coulomb law take a negative sign? That is F = -KQ1Q2/r^2 ?

26. ### Coulomb's law in vector form

Sorry cupid.callin. Now i have incorporated the attachments.
27. ### Coulomb's law in vector form

Homework Statement Revered members, Please see my both attachments. Homework Equations F21 = (q1q2/4∏ε0r122)*r12cap(unit vector) Is it wrong to use r12 instead of r21 for F21. Because my second attachment uses r21 for F21 and r12 or F12. I am confused. Please help which is correct...
28. ### Conductors and their increase of resistance with temperature

Revered members, Conductors have positive temperature coefficient of resistance, that is , their resistance increases with temperature. While for insulators and semi conductors, the resistance decreases with increase in temperature, what we call negative temperature coefficient of resistance...
29. ### Effective Resistance if bent in the form a circle

Thanks a lot stonebridge. Your help is very much appreciated
30. ### Electric potential - doubt in sign convention

Thanks a lot ehild. The link you have given is so wonderful. I understood the concept. Thanks again.
31. ### Binding energy per nucleon

From the graph plotted between Mass Number and Binding Energy per Nucleon, we infer the BE/A is stable for mass numbers between 20 and 60 (approximately) and decreases for A>60. Similarly the BE/A is very less for lighter nuclei, say, Helium. Nuclear forces are short range forces. So it is...
32. ### Electric potential - doubt in sign convention

ok. Now i am confronted with the magnitude of test charge and source charge. Should they be of same magnitude? I presume the test charge is unit positive charge. But i can't get an idea of magnitude of source charge, in the concept of electric potential
33. ### Electric potential - doubt in sign convention

Thanks again. How could we find which point is more positive?
34. ### Electric potential - doubt in sign convention

Thanks ehild. Now, if i choose a point A say 5 cm from X and B at 9 cm from X, which is the point with higher potential?
35. ### Electric potential - doubt in sign convention

Thanks for the detailed explanation, ehild. What is the position of the two points A and B in a electric field? For example, i draw a straight line XY. Where should i position the points A and B that satisfies your explanation? X_________________________________________y
36. ### Electric potential - doubt in sign convention

Electric potential --- doubt in sign convention Homework Statement Revered members, I know dV = -E.dx so E = -dV/dx So E should be E = -V/x . But while deriving capacitance of a parallel plate capacitor when dielectric medium is introduced we use E = V/x. But how E = V/x? Homework...
37. ### Metacentric height

Thanks Spinnor, i meant tanθ, which i erroneously entered as cos. So θ = .02. Do the formula i used to arrive at the solution is correct?
38. ### Metacentric height

Homework Statement In a ship of 10000 tons, the breadth of whose deck is 20 m, a mass of 50 tons is moved from one side to the other causing the bob of a plumb line 10 m long to move over 20 cm. Find the metacentric height? Homework Equations The Attempt at a Solution I don't...
39. ### Change in entropy

Homework Statement What is the change in entropy when 1 gm of ice at 0° C is converted into water at the same temperature? Homework Equations [b]3. The attempt at the solution dS = dQ/T. Q = msT/T so dS = 1*?*273/273 i don't know whether i should substitute specific heat...
40. ### Regarding Inserting Images

Dear Moderators, This forum supports to attach images. Also it supports to insert image from URL. I need help as to How to insert image from a file. For example, i type " Consider the image below" and i have to insert the image below the text instead of attaching the image. How to do it?
41. ### Effective Resistance if bent in the form a circle

Homework Statement A wire of resistance 8R is bent in the form of a circle. What is the effective resistance between the ends of a diameter AB? Homework Equations I have attached the image and my attempt to solve it as told by my teacher. Homework Equations The Attempt at...
42. ### Application of Gauss' law - some doubts

My fourth attachment.
43. ### Application of Gauss' law - some doubts

Application of Gauss' law -- some doubts Homework Statement Revered Members, I have attached images of applications of Gauss' law namely 1) Electric field due to an infinitely long charged wire and 2) Electric field due to an infinite charged plane sheet. In both cases Gaussian surface is...
44. ### Semiconductors - role of displaced Silicon or Germanium

Thanks for the replies. @Dr Transport: Does the displaced atom lie stationary when it becomes interstitial?
45. ### Semiconductors - role of displaced Silicon or Germanium

Semiconductors -- role of displaced Silicon or Germanium Revered Members, When we dope a pure Germanium or Silicon with pentavalent impurity or trivalent impurity, the dopant replaces Silicon or Germanium and bonds with neighbouring Si or Ge atom. That is Dopant takes the centre position and...
46. ### Resolution of vectors

Thanks omoplata. I raised this query in many forums but i could not get any satisfactory reply. Now with your example, i clearly understood the concept. Persons like you are an asset to this forum. Thanks a lot for your valuable help.
47. ### Resolution of vectors

Omaplata, one more doubt. Why vsinθ has no effect in measurement of velocity? Only vcosθ has been taken into account. It has been mentioned since vsinθ is perpendicular to the vertical diameter, it has no effect. I don't understand. Could you clarify?
48. ### Resolution of vectors

Thanks for your kind gesture omaplata. I understood now.
49. ### MS Office 2010 - purchase doubts

Thanks DavidSnider. I ll try Open office first as suggested by you
50. ### MS Office 2010 - purchase doubts

MS Office 2010 -- purchase doubts Dear members, Products like Norton Anti Virus, when bought, is valid for one year or two years depending on the type of purchase and we have to renew the subscription periodically. Whether this applies to MS Office 2010? I plan to buy it. It will be waste of...