AC and DC

• What are the two types of electrical current discussed in the video?

  Direct current (DC) and alternating current (AC)
• What does direct current (DC) mean?


  It is a current that flows in one direction only.
• How does alternating current (AC) differ from direct current (DC)?


  AC constantly changes direction, while DC flows in one direction.
• What is the abbreviation for alternating current?


  AC
• What is a key benefit of using alternating current?


  It is easy to use a transformer to change its potential difference.
• How many times does alternating current switch direction in the UK?


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


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


  Around 230 volts
• What device is used to visualize the pattern of an electrical current?


  An oscilloscope
• What does the height of the peak on an oscilloscope trace indicate?


  The maximum potential difference of the current.
• How can you calculate the frequency of an alternating current using an oscilloscope trace?


  By determining the time for one complete cycle and using the formula frequency = 1 / time.
• If the time between two peaks on an oscilloscope trace is 0.02 seconds, what is the frequency?


  $50 \text{ Hz}$
• What happens to the current in an AC supply as shown on an oscilloscope?


  The potential difference rises and falls, indicating the current goes backwards and forwards.
• What are the features of direct current (DC) as observed on an oscilloscope?


  • The potential difference does not change.
  • The trace appears as a straight line.
• How can you use an oscilloscope to analyze an AC supply?


  • Observe the rising and falling potential difference.
  • Measure the time between peaks to calculate frequency.
  • Determine the maximum potential difference from the peak height.
• What should you know about mains electricity for your exam?

  • Frequency: 50 Hz
  • Potential difference: around 230 volts