18. Alternating current

Question 1

What is alternating current?

Answer 1

Alternating current is a current that varies periodically in direction.

Question 2

What is root-mean-square value of alternating current?

Answer 2

the root-mean-square value of an AC is the value of the steady direct current which produces heat at the same rate as the alternating current in a given resistor.

Question 3

what is root-mean-square voltage?

Answer 3

The root-mean-square voltage is defined as the steady direct voltage which directly produces heat at the same rate as the alternating current across a given resistor.

Question 4

How to calculate the rms current?

Answer 4

I rms = square root of ( area under I² graph for one cycle / one period )

Question 5

What is the sinusoidal current equation?

Answer 5

I = I₀ sin 𝜔t

Question 6

What is an ideal transformer?

Answer 6

An ideal transformer has 100% efficiency where power input = power output.
IpVp = IsPs
Vs/Vp = Ns/Np

Question 7

What is mean power dissipation in an a.c circuit?

Answer 7

< P > = IrmsVrms
= (I₀ / √2 )( V₀ / √2)
= 1/2 I₀ V₀