Short notes
Objective questions (Answers are given below)
- An a.c. current given by i = 14.14 sin (ωt +
π/6) has an r.m.s value of — amperes.
(a) 10
(b) 14.14
(c) 1.96
(d) 7.07
and a phase of — degrees.
(e) 180
(f) 30
(g) − 30
(h) 210 - If e1 = A sin ωt and e2 = B sin (ωt − φ), then
(a) e1 lags e2 by θ
(b) e2 lags e1 by θ
(c) e2 leads e2 by θ
(d) e1 is in phase with e2 - From the two voltage equations eA = Em
sin 100πt and eB = Em sin (100πt + π/6), it
is obvious that
(a) A leads B by 30°
(b) B achieves its maximum value 1/600
second before A does.
(c) B lags behind A
(d) A achieves its zero value 1/600 second
before B. - The r.m.s. value of a half-wave rectified
current is 10A, its value for full-wave
rectification would be — amperes.
(a) 20
(b) 14.14
(c) 20/π
(d) 40/π - A resultant current is made of two components
: a 10 A d.c. component and a sinusoidal
component of maximum value 14.14
A. The average value of the resultant current
is — amperes.
(a) 0 (b) 24.14
(c) 10 (d) 4.14
and r.m.s. value is — amperes.
(e) 10 (f) 14.14
(g) 24.14 (h) 100 - The r.m.s. value of sinusoidal a.c. current
is equal to its value at an angle of — degree
(a) 60 (b) 45 (c) 30 (d) 90 - Two sinusoidal currents are given by the
equations : i2 = 10 sin (ωt + π/3) and i2 = 15
sin (ωt − π/4). The phase difference
between them is — degrees.
(a) 105
(b) 75
(c) 15
(d) 60As sine wave has a frequency of 50 Hz. Its
- As sine wave has a frequency of 50 Hz. Its
angular frequency is — radian/second.
(a) 50/π
(b) 50/2 π
(c) 50 π
(d) 100 π - An a.c. current is given by i = 100 sin 100.
It will achieve a value of 50 A after — second.
(a) 1/600
(b) 1/300
(c) 1/1800
(d) 1/900 - The reactance offered by a capacitor to alternating
current of frequency 50 Hz is 10Ω.
If frequency is increased to 100 Hz reactance
becomes—ohm.
(a) 20 (b) 5
(c) 2.5 (d) 40
1a, f 2. b 3. b 4. b 5. c, f 6. b 7. a 8. d 9. a 10. b