Alternating Current MCQ Level - 2 - Physics MCQ

When capacitance is removed

 when inductance is removed

  From equation (1) and (2) 
So it is condition of resonance.
 So  Z = R = 100Ω
I = V/R = 200/100= 2A
Power  P = I²R = 4 ×100 = 400 W
The correct answer is: 2A, 400Watt.

According to given problem, 

Substituting the value of I from equation (1) in (2)

∴   Initial value of time is not given hence the mean value will be different for various time intervals.
If voltage applied is  V = V_m sint ωt  then i given by equation (1) indicates that it is ahead by V by  δ   where  0 < δ < 90   which indicates that the circuit contains R and C.

The correct answer is: if voltage applied is V= V_msin ωt,  then the circuit must be containing resistance and capacitance

Since V lags current, an inductor can bring it in phase with current.

The correct answer is: connecting an inductor in parallel with the load

Since,  (Also  cosθ  can never be greater than 1)

∴  Current will be leading
In a LCR circuit

 

V = 10; which is less than voltage drop across capacitor.
The correct answer is: none of these

The circuit will have inductive nature if 
Also if circuit has inductive nature will lag behind voltage. 

 the circuit will have resistance nature.
Power factor 
 

Hence  true.

The correct answer is: power factor of circuit will be unity if capacitive reactance equals inductive reactance

P = VI

For an ideal transformer (100% efficient)

 
The correct answer is: 2.5A

From the rating of the bulb, the resistance of the bulb can be calculated

For the bulb to be operated at its rated value the rms current through it should be 1A

If we have all R, L and C then I vs, E will be : 
To obtain a leading phase difference of 
if X_L < X_C and we use all R, L and C in the circuit,
then the resultant graph will be :

which can give a leading phase difference of  π/4.
Similarly if we have only resistance and capacitor then we can obtain a phase difference of  π/4.
(leading) for suitable values of I, X_C and R. But we cannot obtain a leading phase difference of π/4. If we use only capacitor (phase difference of  π/2), or only (inductor and resistor) (phase difference of  π/2), or only resistor (phase difference of 0).

The correct answer is: either capacitor, resistor and inductor or only capacitor and resistor