Practice Questions

Q26.At very high frequencies, the effective impedance of the given circuit will be _________Ω .

Q26.In an electrical circuit, a battery is connected to pass 20 C of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at 15 V . The workdone by the battery is _______ J

Q26.A uniform heating wire of resistance 36 Ω is connected across a potential difference of 240 V . The wire is then cut into half and a potential difference of 240 V is applied across each half separately. The ratio of power dissipation in first case to the total power dissipation in the second case would be 1: 𝑥, where 𝑥 is -1

Q26.The electric field in a region is given by E = 5 E0ˆi + 5 E0ˆj field through a rectangular surface, area 0. 4 m2 parallel to the Y −Z plane is _______ N m2 C−1 .

Q27.A fringe width of 6 mm was produced for two slits separated by 1 mm apart. The screen is placed 10 m away. The wavelength of light used is x nm. The value of x to the nearest integer is ______.

Q27.In Bohr's atomic model, the electron is assumed to revolve in a circular orbit of radius 0. 5 A. If the speed of electron is 2. 2 × 106 m s−1. Then the current associated with the electron will be__________ ×10−2 mA. [Take π as 22 7 ]

Q28.The alternating current is given by, i = {√42 sin( 2πT t) 10} __________ A.

Q28.A series LCR circuit is designed to resonate at an angular frequency ω0 = 105 rad s−1. The circuit draws 16 W power from 120 V source at resonance. The value of resistance R in the circuit is ________ Ω.

Q28.A radioactive substance decays to ( 161 )th of its initial activity in 80 days. The half life of the radioactive substance expressed in days is ________.

Q28.Two identical conducting spheres with negligible volume have 2. 1 nC and −0. 1 nC charges, respectively. They are brought into contact and then separated by a distance of 0. 5 m. The electrostatic force acting between the spheres is ___ ×10−9 N . [Given : 4πε0 = 9×1091 SI unit]

Q28.A plane electromagnetic wave with a frequency of 30 MHz travels in free space. At a particular point in space and time, the electric field is 6 V m−1 . The magnetic field at this point will be x × 10−8 T. The value of x is,

Q29.A bandwidth of 6 MHz is available for 𝐴. 𝑀. transmission. If the maximum audio signal frequency used for modulating the carrier wave is not to exceed 6 kHz . The number of stations that can be broadcasted within this band simultaneously without interfering with each other will be __________. JEE Main 2021 (31 Aug Shift 2) JEE Main Previous Year Paper

Q29.The energy dissipated by a resistor is 10 mJ in 1 s, when an electric current of 2 mA flows through it. The resistance is ________ Ω. (Round off to the Nearest Integer)

Q29. X different wavelength may be observed in the spectrum from a hydrogen sample if the atoms are excited to states with principal quantum number n = 6? The value of X is

Q30.The maximum amplitude for an amplitude modulated wave is found to be 12 V while the minimum amplitude is found to be 3 V . The modulation index is 0. 6x where x is _____.

Q30.The maximum and minimum amplitude of an amplitude modulated wave is 16 V and 8 V respectively. The modulation index for this amplitude modulated wave is x × 10−2 . The value of x is _______. (Round off your answer to the nearest integer) JEE Main 2021 (26 Feb Shift 1) JEE Main Previous Year Paper

Q30.A transmitting antenna has a height of 320 m and that of receiving antenna is 2000 m. The maximum distance between them for satisfactory communication in line of sight mode is d. The value of d is ________ km. = nRT is:

Q30.In the logic circuit shown in the figure, if input A and B are 0 to 1 respectively, the output at Y would be x. The value of x is _________.

Q30.A carrier wave with amplitude of 250 V is amplitude modulated by a sinusoidal base band signal of amplitude 150 V . The ratio of minimum amplitude to maximum amplitude for the amplitude modulated wave is 50: 𝑥, then value of 𝑥, is _________ .

Q30.For the forward biased diode characteristics shown in the figure, the dynamic resistance at ID = 3 mA will be ________ Ω. JEE Main 2021 (20 Jul Shift 2) JEE Main Previous Year Paper

Q30.An amplitude-modulated wave is represented by, Cm(t) = 10(1 + 0. 2 cos 12560t) sin(111 × 104t) V. The modulating frequency in kHz will be JEE Main 2021 (26 Aug Shift 1) JEE Main Previous Year Paper

Q30.An audio signal 𝑣𝑚= 20sin2𝜋1500𝑡 amplitude modulates a carrier 𝑣𝑐= 80sin2𝜋100, 000𝑡. The value of percent modulation is

Q30.A message signal of frequency 20 kHz and peak voltage of 20 V is used to modulate a carrier wave of frequency 1 MHz and peak voltage of 20 V. The modulation index will be:

Q30.A carrier wave VC(t) = 160 sin(2π × 106t) volts is made to vary between Vmax = 200 V and Vmin = 120 V by a message signal Vm(t) = Am sin(2π × 103t) volts. The peak voltage Am of the modulating signal is,

Q31.The correct order of electron gain enthalpy is: (1) S > O > Se > Te (2) O > S > Se > Te (3) S > Se > Te > O (4) Te > Se > S > O