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3 marksElectric Fields

CAPE Physics Unit 2 · 2019 · Paper 2 · Question 1(d)(i)

Electrons are ejected from the lower plate of a parallel plate capacitor with a 3 mm plate separation in a vacuum chamber. The ejected electrons have a range of energies and directions. The upper plate has a voltage of -3 V with respect to the lower plate.

For those electrons which are ejected at right angles to the lower plate, calculate the MAXIMUM initial energy, in joules, they can have if none of them reach the upper plate which has a voltage of –3 V with respect to the lower plate.

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Other parts of this question

  1. 1(a)(i)Define the term 'volt'.[2 marks]
  2. 1(a)(ii)Define the term 'coulomb' and state its relationship to the elementary physical unit of charge.[3 marks]
  3. 1(b)In the equation for Coulomb's law, F = Q₁Q₂ / (4πε₀R²), state the meaning of EACH symbol and its corresponding SI unit.[5 marks]
  4. 1(c)A +100 µC and a test charge of -5 µC are 3 mm apart. Calculate the forces between them.[4 marks]
  5. 1(d)(ii)Determine the MAXIMUM initial velocity of the electrons in (d)(i).[3 marks]
  6. 1(d)(iii)Calculate the acceleration of the electrons in (d)(i).[5 marks]
  7. 1(e)(i)Draw a tangent to the graph in Figure 2 and measure the angle of ejection.[3 marks]
  8. 1(e)(ii)Read off the MAXIMUM height reached from the lower plate.[1 mark]
  9. 1(e)(iii)Read off the distance travelled parallel to the plate before being re-absorbed.[1 mark]

More practice: the rest of this paper · more Electric Fields questions · all CAPE Physics Unit 2 past papers