Practice Questions

Q19.The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be (1) 0 . 5% (2) 50% (3) 2% (4) 30% JEE Main 2022 (26 Jul Shift 2) JEE Main Previous Year Paper

Q19.Identify the logic operation performed by the given circuit (1) AND gate (2) OR gate (3) NOR gate (4) NAND gate

Q19.A hydrogen atom in its ground state absorbs 10. 2 eV of energy. The angular momentum of electron of the hydrogen atom will increase by the value of (Given, Planck's constant = 6. 6 × 10−34 Js ). (1) 2. 10 × 10−34 Js (2) 1. 05 × 10−34 Js (3) 3. 15 × 10−34 Js (4) 4. 2 × 10−34 Js

Q19.An n.p.n transistor with current gain β = 100 in common emitter configuration is shown in figure. The output voltage of the amplifier will be (1) 0. 1 V (2) 1. 0 V (3) 10 V (4) 100 V

Q19.The activity of a radioactive material is 2. 56 × 10−3 Ci. If the half life of the material is 5 days, after how many days the activity will become 2 × 10−5 Ci? JEE Main 2022 (29 Jun Shift 1) JEE Main Previous Year Paper (1) 30 days (2) 35 days (3) 40 days (4) 25 days

Q19.A radio can tune to any station in 6 MHz to 10 MHz band. The value of corresponding wavelength bandwidth will be (1) 4 m (2) 20 m (3) 30 m (4) 50 m

Q19.A travelling microscope has 20 divisions per cm on the main scale while its Vernier scale has total 50 divisions and 25 Vernier scale divisions are equal to 24 main scale divisions, what is the least count of the travelling microscope ? (1) 0. 001 cm (2) 0. 002 mm (3) 0. 002 cm (4) 0. 005 cm

Q19.The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because (1) fractional change in majority carriers produce (2) fractional change in majority carriers produce higher forward bias current higher reverse bias current (3) fractional change in minority carriers produce (4) fractional change in minority carriers produce higher forward bias current higher reverse bias current

Q19.Nucleus A is having mass number 220 and its binding energy per nucleon is 5. 6 MeV . It splits in two fragments B and C of mass numbers 105 and 115 . The binding energy of nucleons in B and C is 6. 4 MeV per nucleon. The energy Q released per fission will be: (1) 0. 8 MeV (2) 275 MeV (3) 220 MeV (4) 176 MeV

Q20.In the circuit, the logical value of 𝐴= 1 or 𝐵= 1 when potential at 𝐴 or 𝐵 is 5 V and the logical value of 𝐴= 0 or 𝐵= 0 when potential at 𝐴 or 𝐵 is 0V. The truth table of the given circuit will be : (1) 𝐴 𝐵𝑌 (2) 𝐴 𝐵𝑌 0 0 0 0 0 0 1 0 0 1 0 1 0 1 0 0 1 1 1 1 1 1 1 1 (3) 𝐴 𝐵𝑌 (4) 𝐴 𝐵𝑌 0 0 0 0 0 1 1 0 0 1 0 1 0 1 0 0 1 1 1 1 0 1 1 0

Q20.In an experiment to find out the diameter of wire using screw gauge, the following observation were noted: (a) Screw moves 0. 5 mm on main scale in one complete rotation (b) Total divisions on circular scale = 50 (c) Main scale reading is 2. 5 mm (d) 45th division of circular scale is in the pitch line (e) Instrument has 0. 03 mm negative error Then the diameter of wire is : (1) 2. 92 mm (2) 2. 54 mm (3) 2. 98 mm (4) 3. 45 mm

Q20.A screw gauge of pitch 0. 5 mm is used to measure the diameter of uniform wire of length 6. 8 cm, the main scale reading is 1. 5 mm and circular scale reading is 7 . The calculated curved surface area of wire to appropriate significant figures is [Screw gauge has 50 divisions on the circular scale] (1) 6. 8 cm2 (2) 3. 4 cm2 (3) 3. 9 cm2 (4) 2. 4 cm2

Q20.Only 2% of the optical source frequency is the available channel bandwidth for an optical communicating system operating at 1000 nm. If an audio signal requires a bandwidth of 8 kHz, how many channels can be accommodated for transmission (1) 375 × 107 (2) 75 × 107 (3) 375 × 108 (4) 75 × 109

Q20.A FM Broad cast transmitter, using modulating signal of frequency 20 kHz has a deviation ratio of 10 . The Bandwidth required for transmission is : (1) 220 kHz (2) 180 kHz (3) 360 kHz (4) 440 kHz

Q20.A sinusoidal wave y(t) = 40 sin(10 × 106πt) is amplitude modulated by another sinusoidal wave x(t) = 20 sin(1000πt). The amplitude of minimum frequency component of modulated signal is (1) 0. 5 (2) 0. 25 (3) 20 (4) 10

Q20.The TV transmission tower at a particular station has a height of 125 m . For doubling the coverage of its range, the height of the tower should be increased by (1) 500 m (2) 375 m (3) 250 m (4) 125 m

Q20.Match List I with List II List I List II (A) Facsimile (I) Static Document Image (B) Guided media Channel (II) Local Broadcast Radio (C) Frequency Modulation (III) Rectangular wave (D) Digital Signal (IV) Optical Fiber Choose the correct answer from the following options (1) A - IV, B - III, C - II, D - I (2) A - I, B - IV, C - II, D - III (3) A - IV, B - II, C - III, D - I (4) A - I, B - II, C - III, D - IV

Q20.Amplitude modulated wave is represented by VAM = 10[1 + 0. 4 cos(2π × 104t)] cos(2π × 107t). The total bandwidth of the amplitude modulated wave is (1) 10 kHz (2) 20 MHz (3) 20 kHz (4) 10 MHz

Q20.A baseband signal of 3. 5 MHz frequency is modulated with a carrier signal of 3. 5 GHz frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal ? (1) 42. 8 m (2) 42. 8 mm (3) 21. 4 mm (4) 21. 4 m

Q20.In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be 6 V and 2 V respectively. The modulation index is (1) 100% (2) 80% (3) 60% (4) 50%

Q20.Identify the correct Logic Gate for the following output (Y ) of two inputs A and B . (1) (2) (3) (4)

Q20.Match List-I with List-II List-I List-II (A) Television signal I. 03 KHz (B) Radio signal II. 20 KHz (C) High Quality Music III. 02 MHz (D) Human speech IV. 06 MHz (1) A −I, B −II, C −III, D −IV (2) A −IV, B −III, C −I, D −II (3) A −IV, B −III, C −II, D −I (4) A −I, B −II, C −IV, D −III

Q20.Read the following statements: (A) Volume of the nucleus is directly proportional to the mass number. (B) Volume of the nucleus is independent of mass number. (C) Density of the nucleus is directly proportional to the mass number. (D) Density of the nucleus is directly proportional to the cube root of the mass number. (E) Density of the nucleus is independent of the mass number. Choose the correct option from the following options. (1) (A) and (D) only. (2) (A) and (E) only. (3) (B) and (E) only. (4) (A) and (C) only

Q20.A signal of 100THz frequency can be transmitted with maximum efficiency by (1) Coaxial cable (2) Optical fibre (3) Twisted pair of copper wires (4) Water

Q20.At a particular station, the TV transmission tower has a height of 100 m. To triple its coverage range, height of the tower should be increased to (1) 200 m (2) 300 m (3) 600 m (4) 900 m