Alternating Current - Quiz 3

ALTERNATING CURRENT QUIZ-3

Dear Readers,

JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts.

Q1. Two alternating voltage generators produce emfs of the same amplitude E₀ but with a phase difference of π/3. The resultant emf is?

•  E₀ sin⁡[ωt+(π/3)]
•  E₀ sin⁡[ωt+(π/6)]
•  √3 E₀ sin⁡[ωt+(π/6)]
•  √3 E₀ sin⁡[ωt+(π/2)]

Solution

Q2. Two alternating voltage generators produce emfs of the same amplitude E₀ but with a phase difference of π/3. The resultant emf is

•  0.1 A
•  0.3 A
•  0.6 A
•  0.2 A

Solution

Q3. A parallel plate capacitor C with plates of unit area and separation d is filled with a liquid of dielectric constant K = 2. The level of liquid is d/3 initially. Suppose the liquid level decreases at a constant speed v, the time constant as a function of time t is.

•  
  
•  
  
•  
  
•  
  

Solution

Q4. For an LCR series circuit with an ac source of angular frequency ω,

•  Circuit will be capacitor if ω>1/√LC
•  Circuit will be inductive if ω=1/√LC
•  Power factor of circuit will be unity if capacitive reactance equals inductive reactance
•  Current will be leading voltage if ω>1/√LC

Solution

Q5. A dc ammeter and a hot wire ammeter are connected to a circuit in series. When a direct current is passed through circuit, the dc ammeter shows 6 A. When ac current flows through circuit, the ac ammeter shows 8 A. What will be reading of each ammeter, if dc and ac currents flow simultaneously through the circuit?

•  dc=6 A,ac=10 A
•  dc=3 A,ac=5 A
•  dc=5 A,ac=8 A
•  dc=2 A,ac=3 A

Solution

Q6. When 100 V dc is applied across a solenoid, a current of 1.0 A flows in it. When 100 V ac is applied across the same coil, the current drops to 0.5 A. If the frequency of the ac source is 50 Hz, the impedance and inductance of the solenoid are

•  200 Ω and 0.55 H
•  100 Ω and 0.86 H
•  200 Ω and 1.0 H
•  100 Ω and 0.93 H

Solution

Q7. When an ac source of emf e=E₀sin⁡(100 t) is connected across a circuit, the phase difference between emf e and current i in the circuit is observed to be π/4 as shown in Fig. If the circuit consists possibly only of R-C or R-C or L-R series, find the relationship between the two elements

•  R=1 kΩ,C=10 μF
•  R=1 kΩ,C=1 μF
•  R=1 kΩ,L=10 H
•  R=1 kΩ,L=1 H

Solution

Q8. In an ac circuit the potential differences across an inductance and resistance joined in series are respectively 16 V and 20 V. The total potential difference across the circuit is

•  20 V
•  25.6 V
•  31.9 V
•  53.5 V

Solution

Q9. A resistor and an inductor are connected to an ac supply of 120 V and 50 Hz. The current in the circuit is 3A. If the power consumed in the circuit is 108 W, then the resistance in the circuit is

•  12 Ω
•  40 Ω
•  √(52×28) Ω
•  360 Ω

Solution

Q10. The voltage time (V-t) graph for triangular wave having peak value V₀ is as shown in Fig. The rms value of V in time interval from t=0 to T/4 is?

•  V₀/√3
•  V₀/2
•  V₀/√2
• None of these

Solution