Chapter 6 - Alternating current

Question 0

Define the term frequency

Answer 0

The number of cycles per second

Question 1

Define the term alternating current

Answer 1

Current that repeatedly changes its direction

Question 2

What is mains frequency?

Answer 2

50Hz

Question 3

Define the term peak value

Answer 3

The maximum current (which is the same is either direction)

Question 4

what is the formula relating frequency and time period

Answer 4

frequency = 1/ time period

Question 5

What is the mean power?

Answer 5

1/2 the peak power of an alternating current

Question 6

Define the term root mean square value (rms)

Answer 6

the value the direct current would give the same power as the a.c.

Question 7

What is the formula used to calculate the Vrms value?

Answer 7

Vrms= V0/root2 where V0= peak voltage

Question 8

How do you calculate frequency from a graph?

Answer 8

1/(time for 1 cycle*time base)

Question 9

How do you measure the speed of an ultrasound?

Answer 9

Look on graph - measure distance from left to peak*time base control
Or do d/t if distance is known