Q.1. An electron oscillating with a frequency of 3 × 106 Hz, would generate
Q.2. Ultraviolet spectrum can be studied by using a
Q.3. Ozone layer above earth’s atmosphere will not
Q.4. Which one of the following has the maximum energy?
Q5. Which of the following has minimum wavelength?
Q.6. The correct option, if speeds of gamma rays, X-rays and microwave are Vg, Vx an Vm respectively will be.
Q.7. Which of the following has maximum penetrating power?
Q.8. Electromagnetic waves travelling in a medium having relative permeability μr = 1.3 and relative permittivity Er = 2.14. The speed of electromagnetic waves in medium must be
Q.9. Electromagnetic waves of frequency …. are reflected from ionosphere.
Q.10. The waves which are electromagnetic in nature are
Q.11. Which of the following is called heat radiation?
Q.12. From Maxwell’s hypothesis, a charging electric field gives rise to
Q.13. The ultra high frequency band of radio waves in electromagnetic wave is used as in
Q.14. Electromagnetic waves are transverse in nature is evident by
Q.15. Which of the following are not electromagnetic waves?
Q.16. 10 cm is a wavelength corresponding to the spectrum of
Q.17. The structure of solids is investigated by using
Q.18.. The condition under which a microwave over heats up a food item containing water molecules most efficiently is
Q.19. If E and B represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along
Q.20. Which of the following statement is false for the properties of em waves?
Q.21. The ozone layer in the atmosphere absorbs
Q.22. Which radiations are used in treatment of muscle ache?
Q.23. Waves in decreasing order of their wavelength are
Q.24. Which of the following is/are true for electromagnetic waves? I. They transport energy. II. They have momentum. III. They travel at different speeds in air depending on their frequency.
Q.25. The amplitude of an electromagnetic wave in vacuum is doubled with no other changes made to the wave. As a result of this doubling of the amplitude, which of the following statements are incorrect? I. The speed of wave propagation chages only II. The frequency of the wave changes only III. The wavelength of the wave changes only
Q.26. Select the correct statement(s) from the following. I. Wavelength of microwaves is greater than that of ultraviolet rays. II. The wavelength of infrared rays is lesser than that of ultraviolet rays. III. The wavelength of microwaves is lesser than that of infrared rays IV. Gamma ray has shortest wavelength in the electromagnetic spectrum
Q.27. Electromagnetic waves with wavelength λ are used by a FM radio station for broadcasting. Here λ belongs to
Q.29. Maxwell in his famous equations of electromagnetism introduced the concept of
Q.30. The conduction current is same as displacement current when source is
Q.31. If a variable frequency ac source is connected to a capacitor then with decrease in frequency the displacement current will
Q.32. An electromagnetic wave can be produced, when charge is
Q.33. Which of the following statement is false for the properties of electromagnetic waves?
Q.34. Which of the following has/have zero average value in a plane electromagnetic wave?
Q.35. A charged particle oscillates about its mean equilibrium position with a frequency of 109 Hz. The frequency of electromagnetic waves produced by the oscillator is
Q.36. Select the wrong statement. EM waves
Q.37. The waves used by artificial satellites for communication is
Q.38. Which of the following electromagnetic waves is used in medicine to destroy cancer cells?
Q.39. Light with an energy flux of 20 W/cm2 falls on a non-reflecting surface at normal incidence. If the surface has an area of 30 cm2, the total momentum delivered (for complete absorption) during 30 minutes is , [NCERT Exemplar]
Q.40. For television broadcasting the frequency employed is normally
Q.41. A plane electromagnetic wave propagating along x direction can have the following pairs of E and B
Q.42. A charged particle oscillates about its mean equilibrium position with a frequency of 109 Hz. For producing electromagnetic waves which one is not true?
Q.43. The source of electromagnetic waves can be a charge
Q.44. One requires 11 eV of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in
Q.45. The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is
Q.46. When electromagnetic waves enter the ionised layer of ionosphere, then the relative permittivity i.e. dielectric constant of the ionised layer
Q.47. Ultraviolet rays coming from sun are absorbed by
Q.48. An EM wave of intensity I falls on a surface kept in vacuum and exerts radiation pressure p on it. Which of the following is not true?
Q.49. In electromagnetic spectrum, the frequencies γ-rays, X-rays and ultraviolet rays are denoted by n1, n2 and n3 respectively then
Q.50. Which one of the following has the shortest wavelength?