Flashcards in Alternating Current Deck (28):

1

## What is the growth of current in a conductor I?

### I= I₀(1-e^-RT/L)

2

## What is the decay of current in a conductor I=?

### I= I₀e^-RT/L

3

## What is the charging of a capacitor q=?

### q= q₀(1-e^-t/RC)

4

## What is the Average value of alternating current I(m)=?

###
I(m)= 2I₀/π=0.637I₀

;I(m)= mean or avg current in one half cycle

I(o)= peak value of Ac

5

## What is the RMS value of alternating current ?

###
I(v)= I₀/√2=0.707I₀

;I(v)= root mean square value of current

6

## What is the Impedance of an AC current Z=?

###
Z= √[R²+(XL-XC)²]

; XL= Inductive reactance

XC= capacitive reactance

Z= Impedance

7

## What is Inductive reactance XL=?

###
XL= ωL=2πfL=2πL/T

; L= Inductance

T= Time period of AC

8

## What is Capacitive Reactance XC=?

###
XC= 1/ωC=1/2πfC=T/2πC

; C= Capacitance

T= Time period of AC

9

## What is Average power in AC circuit P(avg)=?

###
P(avg)= V(rms) i(rms) cos #= Vi/2 cos #

; cos #=Power Factor=R/Z

10

## What is Alternating emf E and alternating current for Pure resistive circuit =?

###
E= E₀ sin ωt

I= I₀ sin ωt

E and I are in the same phase

11

## What is Average power delay P in purely resistive circuit =?

###
P= E(v).I(v)

cos #= 1

12

## What is Alternating emf E and alternating current for Pure inductive circuit =?

###
E= E₀ sin ωt

I= I₀ sin (ωt-π/2)

I lags behind V by π/2

XL= ωL

13

## What is Average power delay P in purely inductive circuit =?

###
P=0

cos #=0

14

## What is Alternating emf E and alternating current for Pure capacitive circuit =?

###
E= E₀ sin ωt

I= I₀ sin (ωt+π/2)

I leads V by π/2

XC= 1/ωC

15

## What is Average power delay P in purely capacitive circuit =?

###
P=0

cos #=0

16

## What is Alternating emf E and alternating current for RC circuit =?

###
E= E₀ sin ωt

I= E₀/Z sin (ωt- δ)

I lags E by δ

XC=1/ωC

17

## What is Impedance Z of a RC circuit =?

### Z= √R²+(1/ωC)²

18

## What is Alternating emf E and alternating current for LC circuit =?

###
E= E₀ sin ωt

I= E₀/Z sin (ωt- δ)

Z= XL-XC=0

19

## What is Alternating emf E and alternating current for LCR circuit =?

###
E= E₀ sin ωt

I= I₀ sin (ωt+#)

I lags/leads E by #

20

## What is Average power P at LCR circuit =?

### P= E(v)I(v) cos #

21

## What is Frequency f in series resonance circuit at XL=XC, Z=R

###
f= 1/2π√LC

Q= 1/R (L/C)^-1/2

Impedance minimum , current maximum

22

## For parallel resonance circuit , XL=XC and Z is ?mum and I is ?mum

###
Z is maximum

I is minimum

23

## What is Induced emf e produced by an AC generator =?

### e= NBA ω sin ωt= e₀ sin ωt

24

## What is Torque in a DC motor =?

###
Torque = NBIA sin #

; A= Area of armature

N= No of turns of conductor

B= magnetic field

25

## In a transformer , if energy loss =0, then what is K=?

### K= N(s)/N(p)= E(s)/E(p)= I(p)/ I(s)

26

## In transformer , if energy loss !=0 then what is K=?

### K=N(s)/N(p)=E(s)/E(p)!=I(p)/I(s)

27

## For step up transformer what is K=?

### K>1

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