A-Level UK (AQA, Edexcel, OCR) · Physics

Fields and capacitors

10 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 10 questions

  1. The gravitational field strength at the Earth's surface is 9.81 N/kg. What is it at a height of one Earth radius above the surface (a distance 2R from the centre)?
  2. A planet's orbital radius around a star is increased by a factor of 4. By what factor does the orbital period change?
  3. Estimate the escape speed from the Earth's surface. (G = 6.67 x 10^-11 N m2 kg-2, M = 5.97 x 10^24 kg, R = 6.37 x 10^6 m)
  4. Two point charges of 2.0 nC and 3.0 nC are 0.030 m apart in a vacuum. What is the force between them? (k = 8.99 x 10^9 N m2 C-2)
  5. A pd of 500 V is applied across two parallel plates 2.0 cm apart. What is the electric field strength between them (assume uniform)?
  6. An electron (m = 9.11 x 10^-31 kg, e = 1.60 x 10^-19 C) is accelerated from rest through a pd of 200 V. What is its final speed?
  7. A 100 microfarad capacitor is charged to 12 V. How much energy is stored?
  8. A 100 microfarad capacitor charged to 12 V discharges through a 10 kilohm resistor. What is the pd after 2.0 s?
  9. Two capacitors of 4.0 microfarad and 12 microfarad are connected in series. What is the total capacitance?
  10. A capacitor discharges through a resistor. After a time equal to one time constant, what fraction of the initial charge remains?

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