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OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER wisedane

OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www.wisedane.com. PHYSICS ELECTROMAGNETIC WAVES SET 2 MCQ’S. Q1. The photo energy in units of eV electromagnetic waves of wavelength 2 cm is :. 2 62. CORRECT ANSWER (c). EXPLANATION.

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OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER wisedane

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  1. OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www.wisedane.com

  2. PHYSICS ELECTROMAGNETIC WAVES SET 2MCQ’S

  3. Q1. The photo energy in units of eV electromagnetic waves of wavelength 2 cm is : • 2 • 62 CORRECT ANSWER (c)

  4. EXPLANATION

  5. Q2. Molybdenum is used as a target element for the production of X-rays because it is : • Light and can easily deflect electrons • Light and can absorb electrons • A heavy element with a high melting point • An element having high thermal conductivity CORRECT ANSWER (C)

  6. EXPLANATION • A heavy element with a high melting point

  7. Q3. If are the speeds of gamma rays, X-rays and mircowaves respectively in vacuum, then CORRECT ANSWER (D)

  8. EXPLANATION

  9. Q4. Which of the following is of shortest wave-length ? • X-rays • Microwaves • Radiowaves CORRECT ANSWER (B)

  10. EXPLANATION

  11. Q5. The wavelength of X-rays lies between • Maximum to finite limits • Minimum to certain limits • Minimum to infinite limits • Infinite to finite limits. CORRECT ANSWER (B)

  12. EXPLANATION • According to Daun-Hunt law, the wavelength of X-rays lies between minimum to certain limit.

  13. Q6. The voltage applied across an X –rays tube is nearly equal to : • 10 V • 100 V • 1000 V • 10,000 V CORRECT ANSWER (D)

  14. EXPLANATION

  15. Q7. X-rays are not used for radar purposes, because they are not • Reflected by target • Partly absorbed by target • Electromagnetic waves • Completely absorbed by target. CORRECT ANSWER (A)

  16. EXPLANATION • X-rays being of high energy radiations, penetrate the target and hence are not reflected back.

  17. Q8. The wavelength of ultraviolet rays is of the order of : • 10-3 m • 10-6m • 10-8m • Between ‘b’ and ‘c’. CORRECT ANSWER (D)

  18. EXPLANATION • The wavelength of ultraviolet rays lies between 100 Å to 3800 Å.

  19. Q9. Which of the following is the infrared wavelength ? • 10-4 cm • 10-5 cm • 10-6 cm • 10-7 cm CORRECT ANSWER (A)

  20. EXPLANATION • The wavelength of infrared region is . • So maximum wavelength of infrared region

  21. Q10. If a source is transmitting electromagnetic wave of frequency then wavelength of the electro-magnetic waves transmitted from the source will be : • 36.6 m • 40.5 m • 42.3 m • 50.9 m CORRECT ANSWER (A)

  22. EXPLANATION

  23. Q11. The magnetic field between the plates of a capacitor when r > R is given by : (where r is the distance from the axis of plates and R is the radius of each plate of capacitor ) • (D) Zero CORRECT ANSWER (C)

  24. EXPLANATION

  25. Q12. The magnetic field between the plates of a capacitor when r < R is given by : • (D) Zero CORRECT ANSWER (A)

  26. EXPLANATION • Consider a loop of radius r (<R) between the two circular plates, placed coaxially with them. The area of the loop . • By symmetry magnetic field is equal in magnitude at all points on the loop. If ID’ is the displacement current crossing the loop and ID is the total displacement current between plates

  27. (i),(ii),(iii) • (i),(ii) • (i) and (iii) only • (i) and (iv) only CORRECT ANSWER (D)

  28. EXPLANATION

  29. Q14. Which of the following relation is correct ? CORRECT ANSWER (B)

  30. EXPLANATION

  31. Q15. An electromagnetic wave, going through vacuum is described by E = E0 sin Which of the following is independent of wavelength ? • K CORRECT ANSWER (C)

  32. EXPLANATION • Where v is the velocity of electromagnetic wave, which is the independent of wavelength of wave but depends upon the nature of medium of propagation of wave.

  33. Q16. A cube of edge a has its edges parallel to x, y and z-axis of rectangular coordinate system. A uniform electric field is parallel to y-axis and a uniform magnetic field is parallel to x- axis. The rate at which energy flows through each face of the cube is : CORRECT ANSWER (B)

  34. EXPLANATION • It shows that the energy will be flowing in faces parallel to plane and is zero in all other faces. Total energy flowing per second from a face in plane

  35. Q17. A radio station on the surface of the earth radiates 50 kW. If transmitter radiates equally in all direction above the surface of earth, what is the amplitude of electric field detected 100 km away ? • 2.45 Vm-1 • 0.245 Vm-1 • 0.0245 Vm-1 • 0.00245 Vm-1 CORRECT ANSWER (C)

  36. EXPLANATION

  37. Q18. An earth orbiting satellite has solar energy collecting panel with total area 5 m2 . if solar radiations are perpendicular and completely absorbed, the average force associated with the radiation pressure is : (solar constant = 4 kWm-2) CORRECT ANSWER (C)

  38. EXPLANATION

  39. Q19. The frequency of electromagnetic wave, which best suited to observe a particle of radius cm is of the order of : • 1015 • 1014 • 1013 • 1012 CORRECT ANSWER (B)

  40. EXPLANATION • Size of particle To observe a particle, the wavelength of electromagnetic waves must be of the size of particle.

  41. Q20. A gold leaf electroscope is charged and the leaves are observed to diverge by a certain amounts. A beam of X-rays is allowed to fall upon the electroscope for a short period. The leaves would • Collapse • Melt • Diverge more • Not diverge more CORRECT ANSWER (D)

  42. EXPLANATION • X – rays being neutral, does not affect the charge on gold leaf electroscope provide photoelectric effect is not involved.

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