Punjab 12th Class Physics Chapter 8 Dawn of Modern Physics Mcqs Test Online Punjab 12th Class Physics Chapter 8 Dawn of Modern Physics Mcqs Test Online 123456789 Question 1 of 9Physics 1. An electron microscope employs which to one of the following principles? 1.Electron can be focused by an electric field 2.Electron can be focused by a magnetic field 3.All of the above 4.Electron have a wave nature Question 1 of 9Question 2 of 9 2. If the K.E of free electron double, its de Broglie wavelength changes by the factor. 1.½ 2.1/√2 3.2 4.√2 Question 2 of 9Question 3 of 9 3. The positron has charge which is in magnitude equal to the charge on: 1.All 2.Proton 3.Electron 4.β-particle Question 3 of 9Question 4 of 9 4. Pair production cannot take place in vacuum because: 1.Energy is not conserved 2.Momentum is not conserved 3.Charge is not conserved 4.Mass is not conserved Question 4 of 9Question 5 of 9 5. Einstein’s photoelectric equation is Ek = hf = φ in this equation Ek refers to: 1.Mean K.E emitted electrons 2.Maximum K.E of emitted electrons 3.K.E of all the emitted electrons 4.Minimum K.E of emitted electrons Question 5 of 9Question 6 of 9 6. We can never accurately describe all aspects of subatomic particles simultaneously. It is correct according to: 1.Photo electric effect 2.De-Broglie Theory 3.Uncertainty Principle 4.Einstein Theory Question 6 of 9Question 7 of 9 7. A perfect absorber must be also be perfect: 1.Radiator 2.Cavity 3.Source of radiation 4.None of them Question 7 of 9Question 8 of 9 8. De-Broglie waves are associated with: 1.Moving charged particles only 2.All particles whether in motion or at rest 3.All moving particles 4.Moving neutral particles only Question 8 of 9Question 9 of 9 9. Pair production occurs only when energy of photon is at least equal to: 1.1.02 Me V 2.1.02 Ge V3.1.02 eV 4.1.02 ke V Question 9 of 9 Loading... Test By Subject Punjab Test By Topics 12th Class Physics You Can Learn and Gain more Knowledge through our Online Quiz and Testing system Just Search your desired Preparation subject at Gotest.