# Isu Physics

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Isu Physics Essay, Research Paper

(d2) multiplied by the proportionality constant known as “Coulomb’s constant” (k) F = k(q1q2) / d2 7. Relative to Coloumb’s point charges means that the two charged spheres must be a great disance apart compared to their own actual dimensions, that the detailed positions of the charged particles making up the magnitude of charge in spere 1 and 2 are not siginificant. 8. The S.I. unit of charge in Coulomb’s Law are called coulombs or “c”, the quantity symbol is “q” and the magnitude for the unit of electric charge is 1 C passes through a standard 60 W light bulb in 2s. 9. The value for k is determined by using a torsion balance. By measuring the resulting twist of placing charges of known magnitude a given distance apart. This value found is for the electric force causing the twist . Coulomb’s constant has two magnitudes which are K=9.0 x 109 (Nm2) / C2 (used to calculate the electric charges between point charges) and k = 2.306 x 10-28 (Nm2) (elem.chg2 ) (used when measuring q1 and q2 in elementary charges) Where N is Newton ,m is meters ,C is coulombs and elem. Chg is the elementary charge) 11.A field is a region of space , altered in some way by the presence of a mass or charge respectively, in which a force will be felt if we place a mass or charge into the field. 12. It is stated that the field is always present around an object and is displayed when it comes in contact or close range with another object, which also has a field around it. Therefore if two objects are moving close together, their forces will meet before contact is made causing the object to react at a distance. Actions depend on the interacting fields 13. A field is represented diagrammatically by drawing a series of force vectors around the charged object. The force vectors show the direction and magnitude of the electric force on a small, positive test charge placed at each and every point in the field. For simplicity reasons, continuos field lines are drawn to show the direction of the force at all points in the field. 14. Electrical field intensit is a vector quantity and is stated to be the electrical force per unit positive charge. E = FE / q where e represents electric field intensity , q represents unit positive charge and FE represents the electrical force. The units are Newton per coulomb. In comparison it is shown that both use N/ ? , where ? is the effecting unit. In the case of gravitational field . mass is the effecting variable , therefore kg are used. In the electric field , coulombs are the effecting variable. 15. In an electric field diagram, the field intensity at any point is indicated by the relative distance between the adjacent field lines. In a region where the electrical field is strong, adjacent field lines are close together and when they are spread widely , it indicates a weaker electric field. The field diagram for a positively and negatively charged sphere a but the vector lines are in opposite direction. 16. The equation for E at a distance of “r” from the center of a small charged sphere is E = K(Q1 / r2) 17. An example of this is parallel plates close together. Each plate would have to be considered as point “n” charges, each point is distributed uniformly side by side on a plane. Therefore, in determining the net electric force at any point in the vicinity of the plates, the contribution from each of the 2 “n” point sources, each a different distance and direction away would have to be considered. 18. The E pattern in the region surrounding 2 positive point charges tends to repel each other. The vector lines tend to curve away from the location of the other point of charge. Except the 90 degree vectord, these tend to go straight towards the other point charge and repel at a 90 degree angle. This also applies for two negative point charges except that the vector lines are pointing in the opposite direction. For a positive and a negative point charge the vector lines tend to curve towards the other point charge. This proves the Law of Electric Charges. 19. In summary to the properties of E between the plates of a charged capacitor, the region outside the two charged plates has an E value of 0 (except for a slight bulge at the ends of the plates). There is a constant value for E everywhere between the parallel plates. All electrical field lines are straight , equally spaced and perpendicular to the parallel plates (except near the edges) depends only on the magnitude of the change of each plate. E is inversely proportional to q, where q is the charge per unit area on each plate. 21. Electric Potential is defined as a unit positive test charge when in the field of any of any other charge. It is a value of potential energy per unit positive charge. It is given the symbol “v”. It represents the amount of work necessary to move a unit positive test charge from rest to infinity to rest at any specific place in a field. 22. The symbol for electric potential in denoted by ” v ” and has the units of volts or joules per coulomb. 23. the equation that is used to determine electric potential at a distance of ” r ” from a spherical point charge “knot” is Ec = (kq1q2) 24. 1 volt is the electrical potential at a point in a electrical field , if 1 joule of work is required to move 1 coulomb of charge from infinity to their point 1V = 1J / C 25.Potential difference or voltage Difference is the work done per unit positive test charge to move one point to another in a field. It is the difference in electric potential between those two points. Electric difference is the work to move from a point in infinity to a point in a field while potential difference is the work to move from one point to another point in the field. 26. The express ion used for the potential difference VAB for a point charge q being moved between two points A and B in an electric field is DEe = q (VB-VA) = qDV 27. As the charge moves in the direction of the electric field it has to fight against the force of the field, making it increasing difficult and making the value of the potential difference higher. On the other hand, if the potential difference is moving in the direction of the field it no longer difference to decrease. Once the velocity of the other ball that is travelling at cetripital velocity in an eliptical denomintaitoin it will ususlly fell inde 28. The expression for the magnitude of the electric field E between parallel plates seperated by a distance ” d ” and connected across a potential difference Vab is E = Vab / d or qVab = qEd 30. In the experiment conducted by R.A. Milikan it was shown that there was a unit of charge which all other units are simple multiples. 31. The apparatus he used was called an electric Microbalance. 32. The accepted value of the magnitude of the charge on an electron is e = 1.602 x 10-19 C 33. The number of electrons required to constitute a coulomb of charge is 6.242 x 1018 e = 1C 34. Three major accomplishments of Robert Andrew Milikan are1. He discovered the Elementary Charge2. He verified Albert Einstein’s Photo Electric effect3. He named and identified the origin and nature of cosmic radiation. 36. A charged particle 9. Moves the electric field of q2 in such a way that the electric potential energy it loses (- DEe ) is equal to the kinetic Energy it gainse (DEk). Practice Problems

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