Practice Questions

Q30.The typical transfer characteristic of a transistor in CE configuration is shown in figure. A load resistor of 2 kΩ is connected in the collector branch of the circuit used. The input resistance of the transistor is 0 . 50 kΩ. The voltage gain of the transistor is

Q30.A modulating signal 2sin6 . 28 × 106𝑡 is added to the carrier signal 4sin12 . 56 × 109𝑡 for amplitude modulation. The combined signal is passed through a non-linear square law device. The output is then passed through a band pass filter. The bandwidth of the output signal of band pass filter will be _____ MHz.

Q30.In an experiment with a convex lens. The plot of the image distance (v′) against the object distance (μ′) measured from the focus gives a curve v′μ′ = 225 . If all the distances are measured in cm. The magnitude of the focal length of the lens is _____ cm.

Q30.In the circuit shown below, maximum Zener diode current will be _____ mA .

Q30.In an experiment of 𝐶𝐸 configuration of 𝑛- 𝑝- 𝑛 transistor, the transfer characteristics are observed as given in figure. JEE Main 2022 (25 Jun Shift 2) JEE Main Previous Year Paper If the input resistance is 200Ω and output resistance is 60Ω, the voltage gain in this experiment will be _____ .

Q30.A transistor is used in common-emitter mode in an amplifier circuit. When a signal of 10 mV is added to the base-emitter voltage, the base current changes by 10μA and the collector current changes by 1. 5 mA . The load resistance is 5kΩ . The voltage gain of the transistor will be _____ .

Q30.A student in the laboratory measures thickness of a wire using screw gauge. The readings are 1. 22 mm, 1. 23 mm, 1. 19 mm and 1. 20 mm . The percentage error is 121x % . The value of x is _____ .

Q30.A telegraph line of length 100 km has a capacity of 0. 01 μF km−1 and it carries an alternating current at 0. 5 kilo cycle per second. If minimum impedance is required, then the value of the inductance that needs to be introduced in series is _____ mH . (If π = √10 )

Q30.A transistor is used in an amplifier circuit in common emitter mode. If the base current changes by 100 μA , it brings a change of 10 mA in collector current. If the load resistance is 2 kΩ and input resistance is 1 kΩ, the value of power gain is x × 104 . The value of x is _____ .

Q30.A freshly prepared radioactive source of half life 2 hours 30 minutes emits radiation which is 64 times the permissible safe level. The minimum time, after which it would be possible to work safely with source, will be _____ hours.

Q30.The Vernier constant of Vernier callipers is 0. 1 mm and it has zero error of (−0. 05 cm). While measuring diameter of a sphere, the main scale reading is 1. 7 cm and coinciding vernier division is 5 . The corrected diameter will be _____ ×10−2 cm.

Q30.Two ideal diodes are connected in the network as shown in figure. The equivalent resistance between A and B is _____ Ω.

Q30.The required height of a TV tower which can cover the population of 6 . 03 lakh is ℎ. If the average population density is 100 per square km and the radius of earth is 6400 km, then the value of ℎ will be _____ m.

Q31.The minimum energy that must be possessed by photons in order to produce the photoelectric effect with platinum metal is: [Given: The threshold frequency of platinum is 1 . 3 × 1015 s-1 and h = 6 . 6 × 10-34Js] (1) 8 . 58 × 10-19J (2) 9 . 76 × 10-20J (3) 3 . 21 × 10-14J (4) 6 . 24 × 10-16J

Q1. In order to determine the Young's Modulus of a wire of radius 0. 2 cm (measured using a scale of least count = 0. 001 cm) and length 1 m (measured using a scale of least count = 1 mm), a weight of mass 1 kg (measured using a scale of least count = 1 g ) was hanged to get the elongation of 0. 5 cm (measured using a scale of least count 0. 001 cm). What will be the fractional error in the value of Young's Modulus determined by this experiment? (1) 0. 14% (2) 0. 9% (3) 9% (4) 1. 4%

Q1. The period of oscillation of a simple pendulum is T = 2π√Lg having a minimum division of 1 mm and time of one complete oscillation is 1. 95 s measured from stopwatch of 0. 01 s resolution. The percentage error in the determination of ′g′ will be: (1) 1. 03% (2) 1. 33% (3) 1. 30% (4) 1. 13%

Q2. Water droplets are coming from an open tap at a particular rate. The spacing between a droplet observed at 4th second after its fall to the next droplet is 34 . 3 m. At what rate the droplets are coming from the tap ? (Take 𝑔= 9 . 8 m s-2) (1) 3 drops/2 seconds (2) 2 drops/second (3) 1 drop/second (4) 1 drop/7 seconds

Q2. A particle is projected with velocity v0 along x-axis. A damping force is acting on the particle which is proportional to the square of the distance from the origin i.e. ma = −αx2. The distance at which the particle stops: (1) 2v0 13 (2) 3mv20 1 ( 3α ) ( 2α ) 3 (3) 3v20 12 (4) 2v20 12 ( 2α ) ( 3α )

Q2. If the angular velocity of earth's spin is increased such that the bodies at the equator start floating, the duration of the day would be approximately : (Take : g = 10 ms−2 , the radius of earth, R = 6400 × 103 m, Take π = 3. 14 ) (1) 60 minutes (2) does not change (3) 1200 minutes (4) 84 minutes

Q2. A stone is dropped from the top of a building. When it crosses a point 5 m below the top, another stone starts to fall from a point 25 m below the top. Both stones reach the bottom of building simultaneously. The height of the building is : (1) 25 m (2) 45 m (3) 35 m (4) 50 m

Q3. The normal reaction N for a vehicle of 800 kg mass, negotiating a turn on a 30° banked road at maximum possible speed without skidding is ____ ×103 kg m s−2 . (1) 10. 2 (2) 7. 2 (3) 12. 4 (4) 6. 96

Q3. A circular hole of radius ( a2 ) is cut out of a circular disc of radius a as shown in figure. The centroid of the remaining circular portion with respect to point O will be: (1) 2 a (2) 5 a 3 6 (3) 1 a (4) 10 a 6 11

Q4. A large block of wood of mass M = 5. 99 kg is hanging from two long massless cords. A bullet of mass m = 10 g is fired into the block and gets embedded in it. The (block + bullet) then swing upwards, their center of mass rising a vertical distance h = 9. 8 cm before the (block + bullet) pendulum comes momentarily to rest at the end of its arc. The speed of the bullet just before the collision is: (Take g = 9. 8 m s−2 ) (1) 841. 4 m s−1 (2) 811. 4 m s−1 (3) 831. 4 m s−1 (4) 821. 4 m s−1

Q4. A body weighs 49 N on a spring balance at the north pole. What will be its weight recorded on the same weighing machine, if it is shifted to the equator? [Use g = GM = 9. 8 m s−2 and radius of earth, R = 6400 km.] R2 (1) 49. 17 N (2) 48. 83 N (3) 49. 83 N (4) 49 N

Q5. If one mole of an ideal gas at (P1, V1) is allowed to expand reversibly and isothermally ( A to B) its pressure is reduced to one-half of the original pressure (see figure). This is followed by a constant volume cooling till its pressure is reduced to one-fourth of the initial value (B →C). Then it is restored to its initial state by a reversible adiabatic compression ( C to A ). The net workdone by the gas is equal to: (1) 0 (2) RT ln(2) − 2(γ−1) (3) − 2(γ−1)RT (4) RT [ln(2) 1 ] JEE Main 2021 (24 Feb Shift 2) JEE Main Previous Year Paper