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Electric Field Questions from 2006 and 2007

Electric Field Questions from 2006 and 2007. The oil drop is stationary. What is its charge?. Force down is its weight. If it is stationary then there must be an electric force up that is equal and opposite to the weight.

johnlrobinson
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Electric Field Questions from 2006 and 2007

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  1. Electric Field Questions from 2006 and 2007

  2. The oil drop is stationary. What is its charge?

  3. Force down is its weight. • If it is stationary then there must be an electric force up that is equal and opposite to the weight.

  4. We therefore know that the charge must be negative (so it is attracted to the upper plate!)

  5. Magnitude of force down = mg Magnitude of force up = QE But E = V/d So magnitude of force up = QV/d

  6. I mg I = I QV/d I So Q = - mgd/V

  7. In a Rutherford scattering experiment, an α particle approaches a gold nucleus along the straight line joining their centres and comes momentarily to rest at point P, as shown in the diagram. The α particle then returns along its previous path. (a) The distance from the centre of the gold nucleus, to the point P is 30 fm. For the point P • show that the strength of the electric field associated with the charge of the nucleus is 1.3 × 1020 V m-1 • calculate the magnitude of the force acting on the α particle • calculate the electric potential due to the charge of the nucleus (5 marks) ,

  8. (b) (i) State the energy changes of the α particle during its interaction with the gold nucleus. (ii) Calculate the initial kinetic energy, in J, of the α particle, explaining your reasoning. (4 marks)

  9. Two protons are 1.0 × 10 -14 m apart. Approximately how many times is the electrostatic force between them greater than the gravitational force between them? A 1023 B 1030 C 1036 D 1042

  10. Two protons are 1.0 × 10 -14 m apart. Approximately how many times is the electrostatic force between them greater than the gravitational force between them? A 1023 B 1030 C 1036 D 1042

  11. (a) (i) Define the electric field strength, E, at a point in an electric field. (ii) State whether E is a scalar or a vector quantity. (3 marks)

  12. (a) (i) Define the electric field strength, E, at a point in an electric field. (ii) State whether E is a scalar or a vector quantity. (3 marks)

  13. (b) Point charges of + 4.0 nC and - 8.0 nC are placed 80 mm apart (i) Calculate the magnitude of the force exerted on the + 4.0 nC charge by the -8.0 nC charge. (ii) Determine the distance from the + 4.0 nC charge to the point, along the straight line between the charges, where the electric potential is zero. • (4 marks)

  14. (c) Point P is equidistant from the two charges. (i) Draw two arrows on the diagram at P to represent the directions and relative magnitudes of the components of the electric field at P due to each of the charges. (ii) Hence draw an arrow, labelled R, at P to represent the direction of the resultant electric field at P. (3 marks)

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