CH-19 Dawn of Modern Physics Leave a Comment / By abdulslambsn@gmail.com / October 6, 2025 Welcome To Your Quiz "CH-19 Dawn of Modern Physics" Click on "Start Quiz" To Continue... 1. Which one of the following waves require a material medium for their propagation: X-rays Light waves Y-rays Sound waves None 2. A non- inertial frame of reference is that: Is always at rest Moves with some acceleration Moves with uniform velocity None of these None 3. All motions are: Uniform Relative Absolute Variable None 4. Due to relative motion of observer and the frame of reference of events time always: Dilates itself Stretches itself Both A and B None of these None 5. When the atomic particles are moving with velocities approaching that of light: Newton's laws become valid Newton's laws become invalid Relativistic effects become prominent None of these None 6. Earth orbital speed is: 30 cm/s 30 km/s 30 m/s 0.3 m/s None 7. Which one of the following physical quantities change with the relativistic speed: Length Time Mass All of above None 8. Due to the relative motion of observer and the frame of reference, time: Contracts Dilates Constant Uniform None 9. The special theory of relativity is based upon: 3 Postulates 2 postulates 4 postulates None of these None 10. If an object moves with speed of light, then its apparent length becomes: Zero Larger Smaller Infinity None 11. According to special theory of relativity, mass and energy are different quantities and: Non- inter convertible Inter convertible No change None of these None 12. At high temperature, the hot body emits the radiation of: High energy and shorter wavelength Longer wavelength and high energy Low energy and shorter wavelength Shorter wavelength None 13. The ratio of the energy E to the corresponding frequency f of the radiation emitted or absorbed is known as: Boltzman constant Steffen's constant Wien's constant Planck's constant None 14. Max Planck awarded the Nobel Prize for his discovery of energy quanta in: 1918 A.D 1920 A.D 1718 A.D 1818 A.D None 15. The electrons behave as waves because they can be: Deflected by electric field Ionize as gas Deflected by magnetic field Diffracted by crystals None 16. In Davison and Germer experiment,nickel crystal acts as : Perfect Reflector Perfect absorber Two dimensional grating Three dimensional grating None 17. The uncertainty principle is applicable only when: Momentum is measured only Position is measured only Both position and momentum are measured None of these None 18. The uncertainly in the location of a particle is equal to its de -Broglie wavelength, then uncertainly in its velocity will be equal to: 4 times its velocity Twice its velocity Half of its velocity It's velocity None 19. The process through which photons can interact with matter is: Photoelectric effect Compton effect Pair production Any of these None 20. Threshold frequency is the: Varies from metal to metal Minimum frequency below which no electron is emitted Same for all metals Both A and B None 21. When the stopping potential is applied to the anode of photos cell, no current is absorbed. This mean: The emission of photoelectrons stops The photo electrons are emitted but are reabsorbed by the photo cathode itself Both A and B None of these None 22. If the energy of photon is 10 eV and work function is 5 eV, then the a value of stopping potential will be: 50 V 2 V 5 V 15 V None 23. In photoelectric emission the energy of emitted electron is: Larger than that of photon Less than that of photon Same as that of photon None of these None 24. The velocity of the photoelectron depends upon: Intensity of incident photon Frequency of incident photon Intensity as well as frequency of incident photon None of these None 25. The study of photoelectric effect is useful for understanding: The quantum nature of matter The wave nature of matter Bohr's atomic model Structure of the nucleus None 26. The maximum number of photoelectrons released in photocell is independent of: Frequency of incident light Nature of the cathode surface Intensity of the radiations None of these None 27. The photoelectric effect is based upon the conservation of: Angular momentum Energy Momentum Mass None 28. The wavelength corresponding to maximum intensity of radiation shifts steadily towards shorter wavelength: The temperature decreases The temperature increases The temperature is constant The temperature is zero None 29. A black body becomes white at a temperature: 1300⁰ C 900⁰ C 1500⁰ C 1600⁰ C None 30. The nature of radiation emitted by a body depends upon: Mass Temperature Volume Pressure None 31. The relation between work function and maximum energy of photoelectrons was discovered by: Stefan Marely Planck Einstein None 32. Compton considered that x-rays consist of: Neutrons Protons Electrons Photons None 33. Author Holy Compton was awarded Nobel Prize in: 1927 1928 1923 1931 None 34. The process of conversion of photons into an electron and a positron is known as: Compton effect Photoelectric effect Pair production None of these None 35. The minimum energy required for the pair production is: 0.21 MeV 0.12 MeV 1.02 MeV None of these None 36. Every particle with corresponding anti-particle with: The same mass Opposite charge Different mass Both A and B None 37. Strictly speaking, the Earth is: Inertial frame of reference Non- inertial frame of reference Both A and B None of these None 38. Earth's orbital speed is: 30 km/s 30 m/s 30 km/h None None 39. The pair production occurs only when energy of photon is at least equal to: 1.02 eV 1.02 Me V 1.2 Me V All None 40. Which one of the following radiation has the strongest photon? Microwaves X-rays Y-rays None of these None 1 out of 8 Thanks For Taking This Quiz - Please See Your Answers/Results Below After Entering Your Name & Email... Name Email Time's up
