WorksheetsAlternating Current
Total questions: 11
Worksheet time: 7mins
In the case of an inductor
(a) voltage lags the current by π/2
(b) voltage leads the current by π/2
(c) voltage leads the current by π/3
(d) voltage leads the current by π/4
In a pure capacitive circuit if the frequency of ac source is doubled, then its capacitive reactance will be
(a) remains same
(b) doubled
(c) halved
(d) zero
In an alternating current circuit consisting of elements in series, the current increases on increasing the frequency of supply. Which of the following elements are likely to constitute the circuit?
(a) Only resistor
(b) Resistor and inductor
(c) Resistor and capacitor
(d) Only inductor
A bulb is connected first with dc and then ac of same voltage then it will shine brightly with
a.c
d.c
Brightness will be in ratio 1/(1.4).
Equally with both.
The voltage of an ac source varies with time according to the equation
V = 100 sin (100π t) cos (100πt), where t is in seconds and V is in volts. Then
the peak voltage of the source is 100 V.
the peak voltage of the source is 50 V.
the peak voltage of the source is 2100 Volt
the frequency of the source is 50 Hz.
The vector diagram of current and voltage for a circuit is as shown. The components of the circuit will be
LCR
LR
LCR or LR
None
L, C and R represent physical quantities inductance, capacitance and resistance, respectively. The combination representing dimension of frequency is
LC
(LC)2−1
(CL)2−1
LC
Power factor is maximum in an LCR series circuit when
XL=XC
R=0
XL =0
XC =0
A transformer is used to light a 100 W and 100 V lamp from a 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is approximately
30%
50%
90%
10%
As the frequency of an ac circuit increases, the current first increases and then decreases. What combination of circuit elements is most likely to comprise the circuit?
a)
Resistor and inductor
b)
Resistor and capacitor
c)
Resistor, inductor and capacitor
d)
None of these
