Practice Questions

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

Q19.An 𝛼 particle and a proton are accelerated from rest through the same potential difference. The ratio of linear momenta acquired by above two particals will be : (1) √2: 1 (2) 2√2: 1 (3) 4√2: 1 (4) 8: 1

Q19.The positive feedback is required by an amplifier to act as an oscillator. The feedback here means (1) External input is necessary to sustain ac signal in (2) A portion of the output power is returned back to output. the input. (3) Feedback can be achieved by LR network. (4) The base-collector junction must be forward biased.

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

Q19.A logic gate circuit has two inputs A and B and output Y . The voltage waveforms of A, B and Y are shown below The logic gate circuit is (1) AND gate (2) OR gate (3) NOR gate (4) NAND gate

Q19.For a constant collector-emitter voltage of 8 V , the collector current of a transistor reached to the value of 6 mA from 4 mA , whereas base current changed from 20 μA to 25 μA value. If transistor is in active state, small signal current gain (current amplification factor) will be (1) 240 (2) 400 (3) 0. 0025 (4) 200

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.The momentum of an electron revolving in 𝑛𝑡ℎ orbit is given by : (Symbols have their usual meanings) (1) 𝑛ℎ (2) 𝑛ℎ 2𝜋𝑟 2𝑟 𝑛ℎ 2𝜋𝑟 (3) (4) 2𝜋 𝑛ℎ

Q20.In a Vernier Caliper 10 divisions of Vernier scale is equal to the 9 divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of zero of the main scale and 4th Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to 1 mm. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between 30 and 31 divisions of main scale reading and 6th Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be: (1) 3 . 02 cm (2) 3 . 06 cm (3) 3 . 10 cm (4) 3 . 20 cm

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.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.We do not transmit low frequency signal to long distances because (a) The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of longer wavelength. (b) Effective power radiated by a long wavelength baseband signal would be high. (c) We want to avoid mixing up signals transmitted by different transmitter simultaneously. (d) Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well. Therefore, the most suitable option will be : (1) All statements are true (2) (a), (b) and (c) are true only (3) (a), (c) and (d) are true only (4) (b), (c) and (d) are true only

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.Choose the correct statement for amplitude modulation (1) Amplitude of modulating signal is varied in (2) Amplitude of modulated signal is varied in accordance with the information signal. accordance with the information signal. (3) Amplitude of carrier signal is varied in (4) Amplitude of modulated signal is varied in accordance with the information signal. accordance with the modulating signal.

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

Q20.In Bohr's atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the electron respectively. Choose the correct option when the electron undergoes transitions to a higher level : (1) All K, P and E increase. (2) K decreases, P and E increase. (3) P decreases, K and E increase. (4) K increases, P and E decrease

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