ALTERNATING CURRENT (MEMORY CAPSULE)

                                                     ALTERNATING CURRENT

1. E = E₀ sin ωt

Here E₀ = Peak or maximum value of A.C

         ω = Angular velocity

2. I = E / R = (E₀ sin ωt) / R = I₀ sin ωt

Here I₀ = Peak or maximum value of A.C and is called current amplitude.

3. T = 2π / ω

Here ω = Angular velocity

4. f = 1 / T = ω / 2π

Here f = Frequency

          T = Time period

          ω = Angular velocity

5. I = I₀ sin ωt = I₀ sin 2π t / T

6. The A.C. supplied to our houses has a frequency of 50 cps or 50 Hz.

7. The average value of A.C. over one complete cycle of A.C. is zero.

8. I _av = 2 / π = 0.637 I₀

9. E _av = 2 / π = 0.637 E₀

10. I _rms = I₀ /√ 2 = 0.707 I₀

11. I₀ = E₀ / √ [R² + (X_L – X_C)²]

Here R = Resistance

          X_L = Inductive reactance

          X_C = Capacitive reactance

12. X_L = 2πf L = ω L

13. X_C = 2πf C = ω C

Here f = Frequency

          ω = Angular velocity             L = Inductance

          C = Capacitance

 14. A series LCR circuit is said to be in the resonance condition when the current through it has its maximum value.

15. Characteristics of series LCR resonant circuit –.

v  Resonance occurs in a series LCR circuit when X_L = X_C.

v  Resonant frequency (f _r) = 1 / 2π√LC

v  The impedance is minimum and purely resistive.

v  The current has a maximum value of (E₀ / R) at resonant condition.

v  The power dissipated in the circuit is maximum and is equal to E _rms ² / R.

v  The current is in the phase with the voltage or the power factor is unity.

v  Series resonance can occur at all value of resistance.

v  The voltage across R is equal to applied EMF.

16. Power in A.C. Circuit –

P _av = E _rms I _rms R / Z

Here R = Resistance                P _av = Average Power

          Z = Impedance

17. Power factor = True power / Apparent power

18. Cos φ = R / Z = R / √ [R² + (ω L – 1/ ω C)]

19. For a purely inductive circuit or capacitive circuit, φ = 90⁰.

So power factor = cos 90⁰ = 0

20. For a purely resistive circuit, φ =0⁰.

So power factor = cos 0⁰ = 1

21. The current in A.C. circuit is said to be wattless if average power consumed in the circuit is zero.

22. Transformer –

v  A transformer is an electrical device for converting an A.C. at low voltage into that a high voltage or vice versa.

v  It works on the principal of mutual induction.

v  Step up transformer –

               If n _s > n _p, E _s > E _p

               A transformer in which voltage across secondary is greater than that across primary is called a step – up transformer.

v  Step down transformer –

               If n _s < n _p, E _s < E _p

A transformer in which voltage across secondary is less than that across primary is called a step – down transformer.

v  Losses in transformer –

        (a) Iron loss

        (b) Copper loss

       (c) Hysteresis loss

       (d) Flux leakage

v  Uses of transformer –

(a) Small transformers are used in radio receivers, telephones, loud speakers, etc.

(b) In stabilised power supplies.

(c) In the transmission of electric energy from the generating stations to the consumers.

23. A.C. Generator –

v  It is a device which converts mechanical energy into alternating form of electrical energy.

v  The working of an A.C. generator is based on the principle of electromagnetic induction.

                             

https://jayphy.blogspot.com/2020/07/electromagnetic-induction-memory-capsule.html?m=1

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Milan Tomic

Hi. I’m Designer of Blog Magic. I’m CEO/Founder of ThemeXpose. I’m Creative Art Director, Web Designer, UI/UX Designer, Interaction Designer, Industrial Designer, Web Developer, Business Enthusiast, StartUp Enthusiast, Speaker, Writer and Photographer. Inspired to make things looks better.

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