Practice Questions

Q29.The number of amplitude modulated broadcast stations that can be accommodated in a 300kHz band width for the highest modulating frequency 15kHz will be: (1) 20 (2) 10 (3) 8 (4) 15

Q29. Truth table for the given circuit will be (1) (2) x y z x y z 0 0 1 0 0 0 0 1 1 0 1 0 1 0 1 1 0 0 1 1 0 1 1 1 (3) (4) x y z x y z 0 0 1 0 0 0 0 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 1 1

Q30.A telephonic communication service is working at a carrier frequency of 10 GHz. Only 10% of it is utilized for transmission. How many telephonic channels can be transmitted simultaneously if each channel requires a bandwidth of 5 kHz ? (1) 2 × 106 (2) 2 × 103 (3) 2 × 104 (4) 2 × 105

Q30.In a screw gauge, 5 complete rotations of the screw cause it to move a linear distance of 0. 25 cm. There are 100 circular scale divisions. The thickness of a wire measured by this screw gauge gives a reading of 4 main scale divisions and 30 circular scale divisions. Assuming negligible error, the thickness of the wire is (1) 0. 4300 cm (2) 0. 3150 cm (3) 0. 0430 cm (4) 0. 2150 cm

Q30.A carrier wave of peak voltage 14 V is used for transmitting a message signal. The peak voltage of the modulating signal given to achieve a modulation index of 80% will be: (1) 22 .4 V (2) 7 V (3) 11 .2 V (4) 28 V

Q1. A physical quantity P is described by the relation P = a 21 b2 c3d−4 . If the relative errors in the measurement of a , b , c and d respectively, are 2% , 1% , 3% and 5%. Then the relative error in P will be: (1) 12% (2) 8% (3) 25% (4) 32%

Q2. A body is thrown vertically upwards. Which one of the following graphs correctly represents the velocity𝑣 vs time 𝑡? (1) (2) (3) (4)

Q2. Which graph corresponds to an object moving with a constant negative acceleration and a positive velocity? (1) (2) (3) (4)

Q7. The variation of acceleration due to gravity 𝑔 with distance 𝑑 from the centre of the earth is best represented by (𝑅= Earth's radius): (1) (2) (3) (4)

Q11.An ideal gas has molecules with 5 degrees of freedom. The ratio of specific heats at constant pressure (Cp) and at constant volume (CV) is: (1) 7 (2) 6 5 (3) 7 (4) 5 2 2

Q14.A standing wave is formed by the superposition of two waves travelling in opposite directions. The transverse displacement is given by, y(x, t) = 0.5 sin( 5π4 x) cos(200πt). What is the speed of the travelling wave moving in the positive x direction? ( x and t are in meter and second, respectively) (1) 120 m s−1 (2) 90 m s−1 (3) 160 m s−1 (4) 180 m s−1 JEE Main 2017 (09 Apr Online) JEE Main Previous Year Paper

Q15.Four closed surfaces and corresponding charge distributions are shown below. Let the respective electric fluxes through the surfaces be ϕ1, ϕ2, ϕ3 and ϕ4 . Then: (1) ϕ1 > ϕ2 > ϕ3 > ϕ4 (2) ϕ1 < ϕ2 = ϕ3 > ϕ4 (3) ϕ1 > ϕ3; ϕ2 < ϕ4 (4) ϕ1 = ϕ2 = ϕ3 = ϕ4

Q19.Which of the following statements is false? (1) Kirchhoff's second law represents energy (2) Wheatstone bridge is the most sensitive when all conservation the four resistances are of the same order of magnitude (3) In a balanced Wheatstone bridge if the cell and (4) A rheostat can be used as a potential divider the galvanometer are exchanged, the null point is disturbed

Q19.A magnetic dipole in a uniform magnetic field has: (Take zero potential energy when magnetic dipole is perpendicular to magnetic field) JEE Main 2017 (08 Apr Online) JEE Main Previous Year Paper (1) Maximum potential energy when the torque is (2) Zero potential energy when the torque is maximum maximum (3) Zero potential energy when the torque is (4) Minimum potential energy when the torque is minimum maximum

Q20.When a current of 5 mA is passed through a galvanometer having a coil of resistance 15 Ω, it shows full- scale deflection. The value of the resistance to be put in series with the galvanometer to convert it into a voltmeter of range 0 - 10 V is: (1) 4.005 × 103 Ω (2) 1.985 × 103 Ω (3) 2.045 × 103 Ω (4) 2.535 × 103 Ω

Q22.Magnetic field in a plane electromagnetic wave is given by, → B = B0 sin(kx + ωt)ˆj T. Expression for corresponding electric field will be: (Where c is speed of light) → → (1) (2) E = −B0c sin(kx + ωt)ˆk V m−1 E = B0c sin(kx −ωt)ˆk V m−1 → → (3) (4) B0 E = B0c sin(kx + ωt)ˆk V m−1 E = c sin(kx + ωt)ˆk V m−1

Q28.The V −I characteristic of a diode is shown in the figure. The ratio of forward to reverse bias resistance is: (1) 100 (2) 106 (3) 10−6 (4) 10

Q29.The current gain of a common emitter amplifier is 69 . If the emitter current is 7. 0 mA , collector current is : (1) 69 mA (2) 0. 69 mA (3) 6. 9 mA (4) 9. 6 mA

Q29.In a common emitter amplifier circuit using an 𝑛- 𝑝- 𝑛 transistor, the phase difference between the input and the output voltages will be: (1) 180° (2) 45° (3) 90° (4) 135°

Q30.In amplitude modulation, the sinusoidal carrier frequency used is denoted by 𝜔𝑐 and the signal frequency is denoted by 𝜔𝑚 . The bandwidth Δ𝜔𝑚 of the signal is such that Δ𝜔𝑚≪𝜔𝑐. Which of the following frequencies is not contained in the modulated wave? (1) 𝜔𝑐- 𝜔𝑚 (2) 𝜔𝑚 (3) 𝜔𝑐 (4) 𝜔𝑚+ 𝜔𝑐 Q31.1 gram of a carbonate M2CO3 on treatment with excess HCl produces 0.01186 moles of CO2 . The molar mass of M2CO3 in gmol-1 is: (1) 84.3 (2) 118.6 (3) 11.86 (4) 1186

Q30.A signal of frequency 20 kHz and peak voltage of 5 Volt is used to modulate a carrier wave of frequency 1. 2 MHz and peak voltage 25 Volts . Choose the correct statement. (1) Modulation index = 5 , side frequency bands are (2) Modulation index = 5 , side frequency bands are at 1400 kHz and 1000 kHz. at 21. 2 kHz and 18. 8 kHz. (3) Modulation index = 0. 2 , side frequency bands (4) Modulation index = 5 , side frequency bands are are at 1220 kHz and 1180 kHz. at 24. 2 kHz and 18. 8 kHz.

Q5. The velocity-time graph of a particle of mass 10 kg is shown in the figure. The net work done on the particle in the first two seconds of the motion is (1) −9300 J (2) 12000 J (3) −4500 J (4) −12000 J

Q8. An astronaut of mass m is working on a satellite orbiting the earth at a distance h from the earth's surface. The radius of the earth is R, while its mass is M . The gravitational pull FG on the astronaut is (1) Zero since astronaut feels weightless (2) GMm < FG < GMmR2 (R+h)2 (3) FG = GMm (4) 0 < FG < GMmR2 (R+h)2

Q10.The ratio of work done by an ideal monoatomic gas to the heat supplied to it in an isobaric process is (1) 2 (2) 3 5 2 (3) 3 (4) 2 5 3 Q11. 200 g water is heated from 40 oC to 60 oC . Ignoring the slight expansion of water, the change in its internal energy is close to (Given specific heat of water = 4184 J kg−1 K−1 ): (1) 167.4 kJ (2) 8.4 kJ (3) 4.2 kJ (4) 16.7 kJ

Q11.Which of the following shows the correct relationship between the pressure ′P′ and density ρ of an ideal gas at constant temperature ? (1) (2) (3) (4) JEE Main 2016 (10 Apr Online) JEE Main Previous Year Paper