DC and AC supply

• What is another name for direct current?

  DC
• What is another name for alternating current?

  AC
• What does an oscilloscope do?

  It visualizes electrical current patterns
• What is the flow of electrons in a circuit called?

  Current
• How does current flow from a cell in a circuit?

  In one direction only
• What is the abbreviation for direct current?

  DC
• What is the key feature of alternating current?

  It constantly changes direction
• Why is alternating current easier to transform?

  It allows easy voltage changes
• How many times does AC switch direction in the UK?

  50 times a second
• What is the frequency of AC in the UK?

  50 hertz
• What is the potential difference of mains electricity in the UK?

  230 volts
• What does the height of the peak on an oscilloscope indicate?

  The maximum potential difference
• How does a direct current appear on an oscilloscope?

  It shows a constant potential difference
• How do you calculate the frequency of an alternating current?

  Frequency = 1 / time for one cycle
• If the time between peaks is $0.02 \text{ seconds}$, what is the frequency?


  50 hertz
• What should you know about mains electricity for your exam?

  Frequency and potential difference
• What are the features of direct current (DC) and alternating current (AC)?

  • DC: Flows in one direction, constant potential difference
  • AC: Changes direction, fluctuating potential difference
• How do you use an oscilloscope to analyze AC supply?

  1. Connect oscilloscope to AC supply
  2. Observe the trace for peaks
  3. Measure time between peaks for frequency
  4. Note the height for potential difference
• What is the relationship between time and frequency in AC?

  • Frequency = 1 / time for one cycle
  • Time is the duration of one complete cycle