Alternating Current - Quiz 5

ALTERNATING CURRENT QUIZ-5

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. In the L-C-R circuit shown, the impedance is

•  500 Ω
•  300 Ω
•  100 Ω
•  200 Ω

Solution

Q2. Figure shows an iron-cored transformer assumed to be 100% efficient. The ratio of the secondary turns to the primary turns is 1:20. A 240 V ac supply is connected to the primary coil and a 6.0 Ω resistor is connected to the secondary coil. What is the current in the primary coil?

•  0.10 A
•  0.14 A
•  2.0 A
•  40 A

Solution

Q3. A current source sends a current I=i₀ cos⁡(ωt). When connected across an unknown load, it gives a voltage output of v=v₀ sin⁡[ωt+(π/4)] across the load. Then the voltage across the current source may be brought in phase with the current through it by

•  Connecting an inductor in series with the load
•  Connecting a capacitor in series with the load
•  Connecting an inductor in parallel with the load
•  Connecting a capacitor in parallel with the load

Solution

Q4. Two sinusoidal voltages of same frequency are shown in Fig. What is the frequency and the phase relationship between the voltages? frequency/Hz phase lead of N over M in rad/s

•  0.4, -π/4
•  2.5, -π/2
•  2.5, +π/2
•  2.5, -π/4

Solution

Q5. In a series LCR circuit the voltage across the resistance, capacitance and inductance is 10 V each. If the capacitance is short circuited, the voltage across the inductance will be

•  10 V
•  10/√2 V
•  (10/3) V
•  20 V

Solution

Q6. An rms voltage of 110 V is applied across a series circuit having a resistance 11 Ω and an impedance 22 Ω. The power consumed is

•  275 W
•  366 W
•  550 W
•  1100 W

Solution

Q7. In an ideal transformer, the voltage and the current in the primary coil are 200 V and 2 A, respectively. If the voltage in the secondary coil is 2000 V, then the value of current in the secondary coil will be

•  0.2 A
•  2 A
•  10 A
•  20 A

Solution

Q8. A 50 W, 100 V lamps is to be connected to ac mains of 200 V, 50 Hz. What capacitor is essential to be put in series with the lamp?

•  25/√2 μF
•  50/(π√3) μF
•  50/√2 μF
•  100/(π√3) μF

Solution

Q9. A typical light dimmer used to dim the stage lights in a theatre consists of a variable induction for L (where inductance is adjustable between zero and L_max) connected in series with a light bulb B as shown in Fig. The mains electrical supply is 220 V at 50 Hz, the light bulb is rated at 220 V, 1100 W. What L_max is required if the rate of energy dissipated in the light bulb is to be varied by a factor of 5 from its upper limit of 1100 W?

•  0.69 H
•  0.28 H
•  0.38 H
•  0.56 H

Solution

Q10. In the circuit shown in Fig, if both the bulbs B₁ and B₂ are identical

•  Their brightness will be the same
•  B₂ will be brighter than B₁
•  B₁ will be brighter than B₂
• Only B₂ will glow because the capacitor has infinite impedance

Solution