Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
History of electromagnetic theory wikipedia , lookup
Electromagnetism wikipedia , lookup
Circular dichroism wikipedia , lookup
Introduction to gauge theory wikipedia , lookup
Spherical wave transformation wikipedia , lookup
Maxwell's equations wikipedia , lookup
Field (physics) wikipedia , lookup
Aharonov–Bohm effect wikipedia , lookup
Lorentz force wikipedia , lookup
Aristotelian physics wikipedia , lookup
Physics JC1 2009 Tutorial 9: Electric Fields Electric Field of Point Charges 4) N2008/H2P3/5 (a) A conducting sphere of radius 0.10 m carries a charge of +0.060 C. The electric field around the sphere is shown in Fig 5.2. (i) By reference to Fig 5.2, suggest why it appears as if the charge is concentrated at the centre of the sphere? (ii) Calculate the magnitude of the electric field strength at the surface of the sphere. [5.40 104 N C-1] (iii) On Fig 5.2, A is 0.40 m from the centre of the sphere and B is 0.50 m from the centre of the sphere. The potential difference between A and B is equal to the potential difference between B and C. Calculate the distance from the centre of the sphere to C. [0.67 m] 5) N2000/II/5 (a) Two isolated metal spheres have charges of +Q and –Q. On Fig. 9, draw lines to represent the electric field in the region between the spheres. (b) A metal sphere C is attached to an insulating rod suspended on a fibre shown in Fig. 10. The support rod can rotate in a horizontal plane about the fibre. The fibre is held at its upper end so that the fibre may be twisted and the angle of twist measured. Sphere C is charged. A second sphere S carrying the same charge as C, is then brought close to C at the same horizontal level. The two spheres, which may be assumed to behave as point charges at the centres of the sphere, repel each other and the support rod rotates as illustrated in Fig 11. The upper end of the fibre is twisted to return the support rod to its original position, as illustrated in Fig 12. When the fibre is twisted, it produces a torque moment on the support rod which is proportional to the angle of twist . (i) Explain what is meant by a torque moment. (ii) Show that the angle of twist gives a measure of the force of repulsion between the two spheres. (iii) In one particular experiment, the angle of twist is when the separation of the centres of the spheres is d and the charge on each sphere is +Q. State and explain the value, in terms of , of the new angle of twist when 1. the separation is increased to 2d and the charge on each sphere remains at +Q. 2. the charge on sphere S is halved ( 1 Q), the charge on sphere C 2 remains at +Q and separation is returned to d. the Uniform Electric Field 6) N2000/I/16 The diagram shows a uniform electric field in which the lines of equal potential are spaced 2.0 cm apart. What is the value of the electric force that is exerted on a charge of +5.0 C when placed in the field? [1.5 10-2 N] 7) N01/I/6 A positive charge is in a uniform electric field as shown. In which of the directions shown must the charge be moved in order to gain electric potential energy?