Practice Questions

Q29.The typical output characteristics curve for a transistor working in the common-emitter configuration is shown in the figure. The estimated current gain from the figure is

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.White light is passed through a double slit and interference is observed on a screen 1. 5 m away. The separation between the slits is 0. 3 mm . The first violet and red fringes are formed 2. 0 mm and 3. 5 mm away from the central white fringes. The difference in wavelengths of red and violet light is (in nm).

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.In a semiconductor, the number density of intrinsic charge carriers at 27°C is 1. 5 × 1016 m−3 . If the semiconductor is doped with an impurity atom, the hole density increases to 4. 5 × 1022 m−3 . The electron density in the doped semiconductor is _______ ×109 m−3

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.An inductor of 10 mH is connected to a 20 V battery through a resistor of 10 kΩ and a switch. After a long time, when maximum current is set up in the circuit, the current is switched off. The current in the circuit after 𝑥 1 μs is mA. Then 𝑥 is equal to ______ . (Take 𝑒-1 = 0 . 37) 100

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.The image of an object placed in air formed by a convex refracting surface is at a distance of 10 m behind the surface. The image is real and is at 2rd of the distance of the object from the surface. The wavelength of light 3 inside the surface is 2 times the wavelength in air. The radius of the curved surface is x m , the value of x 3 13 is ______ .

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.Two satellites revolve around a planet in coplanar circular orbits in anticlockwise direction. Their period of revolutions are 1 hour and 8 hours respectively. The radius of the orbit of nearer satellite is 2 × 103 km . The angular speed of the farther satellite as observed from the nearer satellite at the instant when both the satellites are closest is 𝜋 h-1, where 𝑥 is _______ . 𝑥rad

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

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

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 value of power dissipated across the zener diode (Vz = 15 V) connected in the circuit as shown in the figure is x × 10−1 W. The value of x to the nearest integer is _______.

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.The circuit contains two diodes each with a forward resistance of 50 Ω and with infinite reverse resistance. If the battery voltage is 6 V , the current through the 120 Ω resistance is _______ mA

Q29.The voltage across the 10 Ω resistor in the given circuit is x volt. The value of x to the nearest integer is _____.

Q29.A source of light is placed in front of a screen. The intensity of light on the screen is I . Two Polaroids P1 and P2 are so placed in between the source of light and screen that the intensity of light on the screen is I2 . Then the P2 , should be rotated by an angle of (degrees) so that the intensity of light on the screen becomes 3I8 .

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.The wavelength of an X-ray beam is 10 Å . The mass of a fictitious particle having the same energy as that of the X-ray photons is x h kg. The value of x is ___ . ( h =Planck's constant) 3

Q30.If the highest frequency modulating a carrier is 5 kHz, then the number of AM broadcast stations accommodated in a 90 kHz bandwidth are

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.For the given circuit, the power across zener diode is _____ mW .