charging capacitors

• equipment

  • electrolytic capacitor
  • resistor
  • battery
  • voltmeter
  • switch
• method

  • set up apparatus
  • close switch and record voltage reading at t=0 and 5s intervals as capacitor charges until 120s
  • repeat experiment twice more and find average voltage for each time
  • can be repeated with different resistors or capacitors
• graphs and calculations

  • plot graph of voltage against time
  • exponential growth curve
  • $V=$$V_0\left(1-e^{-\frac{t}{RC}}\right)$
• safety

  • battery can explode and release harmful chemicals

  precautions

  • ensure capacitor is connected with correct polarity and voltage rating exceeds voltage of battery
• improvements

  • time constant can be found from exponential growth curve by finding time when voltage is 63% of maximum voltage