Alternating currents Flashcards Preview

A2 Physics F > Alternating currents > Flashcards

Flashcards in Alternating currents Deck (10):
1

What is alternating current or voltage?

  • one that changes direction at time
  • voltage acrtoss a resistance goes up and down in a regular pattern
    • some of the time its positive and some of the time its negative

 

 

2

What is an oscilliscope used for>?

  • display the voltage of an alternating current (and direct too)
  • like fancy voltmeters
  • vertical heigh of the trace at any point shows the input voltage at that point

 

 

3

What is the grid on the oscilliscope?

  • select how many volts per division you want on the y axis scale to represent the y-gain control dial 

 

 

4

What is the pattern of an alternating current and a DC?

 

What happens if you turn time base off?>

  • gives a regularly repeating sinusodial waveform
  • DC gives straigh line, always same voltage
  • time base off - displayed as vertical line for ac, and dot for DC

A image thumb
5

What is peak voltage?

  • `V0
  • ampltude

 

6

What is peak-to-peak voltage?

  • distance between peak to trough

 

 

7

Peak voltage of ac = 2.0V

whyu will this not have a same power supply a 2V dc 

what do you need to do to compare?

  • will be below 2 V most of the time
  • won't have as high power output as 2 V dc supply
  • need to take root mean squre (rms) voltage
    • equation on data sheet
    • same can be done for current

 

8

How do you work of the rms power?

  • powerrms = Irms x Vrms

9

How is the freq on a oscilliscoep worked out

  • as long as time base setting is known
  • 1 / T
  • measuer distance between successive peaks along the time (horizontal) axis gives time period

10

What is the UK's mains electrical supply?

  • 230 V although it does vary
  • it is the rms value