1. A beam of electrons is moving with constant velocity undeviated in a region having electric and magnetic fields of strength 20 Vm–1 and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons?

(a) 20 ms–1 (b) 40 ms–1

(c) 8 ms–1 (d) 5.5 ms–1

2. To an astronaut, the outer space appears (a) blue (b) white (c) black (d) crimson

3. In a discharge tube, at 0.02 mm, there is formation of (a) faraday’s dark space (b) crooke’s dark space (c) both spaces partly (d) crooke’s dark space with glow near the electrodes 4. According to Bohr’s principle the relation between main quantum number (n) and

radius (r) of the orbit is (a) r µ 1/n (b) r µ n (c) r µ n2 (d) r µ 1/n2

5. The energy of a hydrogen atom in its ground state is – 13.6 eV. The energy of the level corresponding to the quantum number n = 2 in the hydrogen atom is

(a) –�2.72 eV (b) –�0.85 eV (c) –�0.54 eV (d) –�3.4 eV 6. When using a triode as an amplifier electrons are emitted by (a) the anode and collected by the grid and by cathode (b) the anode and collected by cathode only (c) the grid and collected by cathode only (d) the cathode and collected by the anode only 7. When arsenic is added as an impurity to silicon, the resulting material is (a) n type semiconductor (b) p type semiconductor (c) n type conductor (d) none of these 8. When npn transistor is used as an amplifier, then (a) electrons move from emitter to collector (b) holes move from emitter to base (c) electrons move from collector to base (d) holes move from base to emitter 9. Ionisation potential of hydrogen atom is 13.6 eV. Hydrogen atoms in the ground

state are excited by monochromatic radiation of photon energy 12.1 eV. The spectral lines emitted by hydrogen atoms according to Bohr’s theory will be

(a) one (b) two (c) three (d) four 10. The mass of photon at rest is (a) zero (b) hv (c) hc/l (d) hv/c.

11. Bragg’s equation will have no solution if (a) λ > 2d (b) λ < 2d (c) λ < d (d) λ = d 12. To draw maximum current from a combination of cells, how should the cells be

grouped? (a) series (b) parallel (c) mixed

(d) depends upon the relative values of external and internal resistance 13. The X-ray tube is operated at 50 kV. The minimum wavelength produced is (a) 0.5 Å (b) 0.75 Å (c) 0.25 Å (d) 1.0 Å 14. Energy of 1g uranium is equal to (a) 9.0�×�1013 J (b) 9.0�×�1019�J (c) 3.0�×�1016�J (d) 3.0�×�1017 J 15. 1H1 + 1H1 + 1H2 → X + 1e0 + Energy. The emitted particle is (a) neutron (b) proton (c) particle (d) nutrino 16. KE of an emitted cathode rays is dependent on (a) only voltage (b) only work function (c) both (a) and (b) (d) it does not depend upon any physical quantity 17. To increase the magnifying power of telescope, we should increase

(a) the focal length of the objective (b) the focal length of the eyepiece (c) aperture of the objective (d) aperture of the eyepiece

18. Transformer is based upon the principle of (a) self induction (b) mutual induction (c) eddy current (d) none of these

19. The wavelength of maximum energy released during an atomic explosion was 2.93�×�10–10 m. Given that the wien’s constant is 2.93�×�10–3 mK, the maximum temperature attained must be of the order of

(a) 10–7 K (b) 107 K (c) 10–13 K (d) 5.86×�107 K 20. The ratio of the frequencies of the long wavelength limits of the Lyman and Balmer

series of hydrogen is (a) 27 : 5 (b) 5 : 27 (c) 4 : 1 (d) 1 : 4 21. Evidence for the wave nature of light cannot be obtained from (a) reflection (b) doppler effect

(c) interference (d) diffraction 22. Which of the following transitions in a hydrogen atom emits photon of the highest

frequency? (a) n = 1 to n = 2 (b) n = 2 to n = 1 (c) n = 2 to n = 6 (d) n = 6 to n = 2. 23. The radioactive nucleus 7N13 decays to 6C13 through the emission of (a) neutron (b) proton (c) electron (d) positron 24. A freshly prepared radioactive substance of half-life 2 hours emits radiations of intensity

64 times the permissible safe level. The minimum time after which it would be possible to work safely with this substance is

(a) 6 hours (b) 12 hours (c) 24 hours (d) 128 hours 25. Fusion reactions takes place at high temperature because (a) atoms are ionised at high temperature (b) molecules break up at high temperature (c) nuclei break up at high temperature (d) Kinetic energy is high enough to overcome repulsion between the nuclei 26. The X-rays beam coming from an X-ray tube will be (a) monochromatic (b) having all wavelengths smaller than a certain minimum wavelength (c) having all wavelengths larger than a certain minimum wavelength (d) having all wavelengths between certain minimum and maximum wavelength 27. Transformers are used in

(a) DC circuits alone (b) AC circuit alone (c) both AC and DC circuits (d) integrated circuits

28. If an electron jumps from 1st orbit to 3rd orbit, then it will (a) absorb energy (b) release energy (c) have no gain of energy (d) none of these 29. The half-life of radium is 1600 years. The number of undecayed atoms of radium

after 4800 years will be (a) 1/8 (b) 1/16 (c) 7/8 (d) 8/7 30. The expected energy of the electrons at absolute zero is called (a) fermi energy (b) emission energy (c) work function (d) potential energy

31. The initial nucleus of uranium series is 92U238 and the final nucleus is 82Pb206. Uranium decays to lead in how many α and β particles?

(a) 6, 8 (b) 8, 6 (c) 4, 3 (d) 3, 4 32. What will be the ratio of the de-Broglie wavelengths of proton and α particle of same

energy? (a) 2:1 (b) 1:2 (c) 4:1 (d) 1:4 33. The radius of the orbital of electon in the hydrogen atom is 0.5�Š.The speed of the

electron is 2�×�106 ms–1. Then the current in the loop due to the motion of the electron is:

(a) 1 mA (b) 1.5 mA (c) 2.5 mA (d) 1.5×10–2�A 34. At any instant the ratio of the amount of radioactive substances is 2:1. If their half-

lives be respectively 12 and 16 hours, then after two days, what will be the ratio of the substances?

(a) 1:1 (b) 2:1 (c) 1:2 (d) 1:4 35. If the half-life of a radioactive substance is T, then its decay constant λ is given by (a) λT = 1 (b) λT = 1/2 (c) λT = loge 2 (d) λ=– loge 27 36. Which of the following isotopes is used for the treatment of cancer? (a) K40 (b) Co60

(c) SR90 (D) I131

37. What determines the hardness of the X-rays obtained from the coolidge tube? (a) current in the filament (b) pressure of air in the tube (c) nature of target (d) potential difference between cathode and target 38. Water cannot be used to extinguish fire caused by an electric current because

(a) it may cause another short circuit (b) it may cause hydrolysis (c) it may cause electrocution (d) it will spoil the wiring

39. What percentage of radioactive substance is left after 5 half-lives? (a) 31% (b) 3.125% (c) 0.3% (d) 1% 40. The first line of Balmer series has wavelength 6563 Å . What will be the wavelength

of the first member of Lyman series? (a) 1215.4 Å (b) 2500 Å (c) 7500 Å (d) 600 Å 41. If half-life of a radioactive atom is 2.3 days then its decay constant would be (a) 0.1 (b) 0.2 (c) 0.3 (d) 2.3

42. β-rays emitted from a radioactive material are (a) electromagnetic radiations (b) electron orbiting around the nucleus (c) charged particles emitted by the nucleus (d) neutral particles 43. Diode can work as (a) oscillator (b) multivibrator (c) modulator (d) rectifier 44. Rutherford’s ∝ scattering particle concludes that (a) there is a heavy mass at centre (b) electrons are revolving around the nucleus (c) both (a) and (b) (d) none of these 45. A radioactive element 90X238 decay into 83Y222. The number of �b particles emitted are (a) 4 (b) 6 (c) 2 (d) 1 46. A radio isotope has a half-life of 75 years. The fraction of the atoms of this material

that would decay in 150 years will be (a) 66.6% (b) 85.5% (c) 62.5% (d) 75% 47. In a nuclear reaction, which of the following is conserved (a) atomic number (b) mass number (c) atomic number, mass number and energy (d) none the above 48. What is the momentum of a photon having frequency 1.5�×�1013 Hz? (a) 3.3�×�10–29 kgms–1

(b) 3.3�×�10–34 kgms–1

(c) 6.6�×�10–34 kgms–1 (d) 3.3�×�10–30 kgms–1

49. Which of the following electromagnetic wave has minimum frequency? (a) radio wave (b) ultravoilet waves (c) microwave (d) infrared wave 50. The energy of a photon of light of wavelength 450 nm is (a) 4.4�×�10–19J (b) 2.5×�10–19�J (c) 1.25�×�10–17J (d) 2�×�10–17�J 51. Water has maximum density at

(a) room temperature (b) 0°C (c) 4°C

(d) 100°C

52. How many NAND gates are used to form AND gate? (a) 1 (b) 2

(c) 3 (d) 4 53. The following Truth table belongs to which one of the following four gates? A B Y 1 1 0 1 0 0 0 1 0 0 0 1 (a) OR (b) NAND (c) XOR (d) NOR 54. What causes changes in the colours of the soap or oil films for the given beam of

light? (a) angle of incidence (b) angle of reflection (c) thickness of film (d) none of these

55. What determines the nature of the path followed by the particle? (a) speed (b) velocity (c) acceleration (d) none of these

56. To obtain a p type germanium semiconductor, it must be doped with (a) arsenic (b) antimony (c) indium (d) phosphorus 57. What do we call a substance that is repelled by a magnet?

(a) paramagnetic (b) diamagnetic (c) ferromagnetic (d) none of these 58. A free neutron decays into a proton, an electron and (a) a neutrino (b) an antineutrino (c) an alpha particle (d) a beta particle 59. Which of the following is used as a moderator in nuclear reactors? (a) uranium (b) heavy water (c) cadmium (d) plutonium 60. The activity of a radioactive sample is measured as 9750 counts per minute at t = 0

and as 975 counts per minute at t = 5 minutes. The decay constant is approx- imately (in per minute)

(a) 0.230 (b) 0.461 (c) 0.461 (d) 0.922 Answer Keys 1. (b) 2. (c) 3. (b)4. (c) 5. (d) 6. (d) 7. (a) 8. (a) 9. (c)10. (a) 11. (a) 12. (d) 13. (c) 14. (a) 15. (c) 16. (c) 17. (a) 18. (b) 19. (b) 20. (b) 21. (a) 22. (b) 23. (d) 24. (b) 25. (d) 26. (c) 27. (b) 28. (a) 29. (a) 30. (a) 31. (b) 32. (a) 33. (a) 34. (a) 35. (c) 36. (b) 37. (d) 38. (a) 39. (b) 40. (a)

41. (c) 42. (c) 43. (d) 44. (a) 45. (d) 46. (d) 47. (c) 48. (a) 49. (a) 50. (a) 51. (c) 52. (b) 53. (d) 54. (c) 55. (d) 56. (c) 57. (b) 58. (b) 59. (b) 60. (b)