Practice Questions

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

Q28.In a parallel plate capacitor set up, the plate area of capacitor is 2 m2 and the plates are separated by 1 m. If the space between the plates are filled with a dielectric material of thickness 0. 5 m and are 2 m2 (see figure) the capacitance of the set-up will be ε0 ________. (Dielectric constant of the material = 3. 2 ) (Round off to the Nearest Integer)

Q28.In a Young's double slit experiment, the slits are separated by 0 . 3 mm and the screen is 1 . 5 m away from the plane of slits. Distance between fourth bright fringes on both sides of central bright fringe is 2 . 4 cm . The frequency of light used is 𝑥× 1014 Hz .

Q28.The first three spectral lines of H-atom in the Balmer series are given λ1, λ2, λ3 considering the Bohr atomic model, the wave lengths of first and third spectral lines ( λ1λ3 ) are related by a factor of approximately x JEE Main 2021 (16 Mar Shift 1) JEE Main Previous Year Paper ×10−1 . The value of x, to the nearest integer, is ________.

Q28.In an electric circuit, a call of certain emf provides a potential difference of 1. 25 V across a load resistance of 5 Ω. However, it provides a potential difference of 1 V across a load resistance of 2 Ω.The emf of the cell is given by x V. Then the value of x is . 10 = √3) suffers minimum deviation. It is found that the angle of

Q28.Two wires of same length and thickness having specific resistances 6 Ω cm and 3 Ω cm respectively are connected in parallel. The effective resistivity is ρ Ωcm. The value of ρ to the nearest integer, is ___ .

Q28.The nuclear activity of a radioactive element becomes ( 81 ) th radioactive element is ________ years.

Q28.A radiation is emitted by 1000 W bulb and it generates an electric field and magnetic field at P , placed at a distance of 2 m . The efficiency of the bulb is 1. 25% . The value of peak electric field at P is x × 10−1 V m−1 . Value of x is (Rounded-off to the nearest integer) [Take ε0 = 8. 85 × 10−12 C2 N−1 m−2, c = 3 × 106 m s−1 ]

Q28.The electric field in a plane electromagnetic wave is given by → E = 200 cos[(0. 5 × 103 m−1)x −(1. 5 × 1011 rad s−1)t] V m−1 ˆj. If this wave falls normally on a perfectly reflecting surface having an area of 100 cm2 . If the radiation pressure exerted by the E.M. wave on the surface during a 10 min exposure is k N m−2 . Find the value of k 109

Q28.The difference in the number of waves when yellow light propagates through air and vacuum columns of the same thickness is one. The thickness of the air column is _____ mm. [Refractive index of air = 1. 0003, the ∘ wavelength of yellow light in vacuum = 6000 A]

Q28.The circuit shown in the figure consists of a charged capacitor of capacity 3 μF and a charge of 30 μC. At time t = 0, when the key is closed, the value of current flowing through the 5 MΩ resistor is x μA. The value of x to the nearest integer is

Q28.The temperature of 3 . 00 mol of an ideal diatomic gas is increased by 40 . 0°C without changing the pressure of the gas. The molecules in the gas rotate but do not oscillate. If the ratio of change in internal energy of the 𝑥 gas to the amount of workdone by the gas is . Then the value of 𝑥 (round off to the nearest integer) is 10 _________ . ( Given𝑅= 8 . 31 J mol-1 K-1

Q28.An object is placed at a distance of 12 cm from a convex lens. A convex mirror of focal length 15 cm is placed on another side of the lens at 8 cm as shown in the figure. The image of the object coincides with the object. When the convex mirror is removed, a real and inverted image is formed at a position. The distance of the image from the object will be ___ cm JEE Main 2021 (26 Aug Shift 2) JEE Main Previous Year Paper

Q28.In an LCR series circuit, an inductor 30 mH and a resistor 1 Ω are connected to an AC source of angular frequency 300 rad s−1. The value of capacitance for which the current leads the voltage by 45° is 1 × 10−3 F . Then the value of x is x

Q29.A transistor is connected in common emitter circuit configuration, the collector supply voltage is 10 V and the voltage drop across a resistor of 1000 Ω in the collector circuit is 0. 6 V. If the current gain factor (β) is 24, then the base current is ____ μA . (Round off to the Nearest Integer)

Q29.The electric field in an electromagnetic wave is given by E = (50 N C−1) sin ω(t −xc ) The energy contained in a cylinder of volume V is 5. 5 × 10−12 J. The value of V is _______ cm3. (given ϵ0 = 8. 8 × 10−12C2 N−1 m−2 )

Q29.A transmitting station releases waves of wavelength 960 m. A capacitor of 2. 56 μF is used in the resonant circuit. The self-inductance of coil necessary for resonance is x × 10−8 H . find x

Q29.An electromagnetic wave of frequency 3 GHz enters a dielectric medium of relative electric permittivity 2. 25 from vacuum. The wavelength of this wave in that medium will be _________ ×10−2 cm.

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

Q29.A zener diode having zener voltage 8 V and power dissipation rating of 0. 5 W is connected across a potential divider arranged with maximum potential drop across zener diode is as shown in the diagram. The value of protective resistance Rp is _____ Ω.

Q29.If 2. 5 × 10−6 N average force is exerted by a light wave on a non-reflecting surface of 30 cm2 area during 40 min of time span, the energy flux of light just before it falls on the surface is _______ W cm−2. (Round off to the Nearest Integer), (Assume complete absorption and normal incidence conditions are there)

Q29.In connection with the circuit drawn below, the value of current flowing through 2 kΩ resistor is______ × 10-4 A .

Q29.A current of 6 A enters one corner P of an equilateral triangle PQR having 3 wires of resistance 2 Ω each and leaves by the corner R. The currents i1 in ampere is

Q29.The zener diode has a Vz = 30 V . The current passing through the diode for the following circuit is___ mA.

Q29.A circuit is arranged as shown in figure. The output voltage Vo is equal to __________ V.