Exercise

EXERCISE

1. A resistor carries two alternative currents having same frequency and phase and having the same peak value of 20 A. One is sinusoidal and the other is rectangular in wave form. Find the rms value of the resultant current.

[Ans: 24.5 A]

Calculate the average value and effective value of a periodic current wave having the following values for equal time intervals over half-cycle, changing suddenly from one value to the next. 0, 50, 70, 90, 110, 90, 70, 50, 0 and also calculate form-factor and peak factor. To suley 2M

3. The applied voltage to an A.C. circuit is v = 200 sin 314 t and the current flowing is i = 20 sin Isbioauntla a 100 314 t. Find the following:

(a) Peak values of voltage and current.  [Ans: 200 V and 20 A]

(b) Frequency of the voltage and current    [Ans: 50 cps]

(c) Effective values of voltage and current [Ans: 141.4 V, 14.14 A]]

(d) The circuit element and its value [Ans: R = 10Ω]

(e) Power factor and   [Ans: p.f. = 1]

(f) Draw the phasor diagram.

4. In problem no. 3, the current I = 10 sin (314 t – π/2), the voltage being same. What is the circuit element? If this element is doubled, what is the rms value of the current. What is the phase angle?

[Ans : Inductance, 3.535 A, ϕ = π/2 lag]

5. In a circuit, having single element i = 4 sin (314 t + π/2) and the voltage v = 60 sin 314 t.

(a) Represent voltage and current in polar form.

(b) Find the phase angle and power factor.

(c) Identify the circuit element and find its value.

 (d) Draw the phasor diagram by taking (i) voltage as reference, (ii) current as reference.

 [Ans: V = 42.42 ∠ 0°, 1 = 2.83 ∠ π/2, ϕ = π/2 lead, p.f. = 0 lead,