Two sources of light are coherent if they emit rays of_______________?

Related Mcqs:

1. Two coherent sources of light produce interference (destructive) when the phase difference between them is _________?

   A. π
   B. 2π
   C. π/2
   D. π/4

   Submitted by: Rizwan Ayub Saadi

2. Hydrogen atom does not emit X-rays because _________________?

   A. its energy levels are too close to each other
   B. its energy levels are too far apart
   C. it is too small in size
   D. it has a single electron

3. If a convex lens of large aperture fails to converge the light rays incident on it to a single point, it is said to suffer from______________?

   A. chromatic aberration
   B. spherical aberration
   C. both spherical and chromatic
   D. distortion

4. A point where the incident parallel rays of light converge or appear to diverge after passing through a lens is called______________?

   A. center of curvature
   B. focus
   C. optical center
   D. aperture

5. T.V sets and microwave ovens emit ___________________?

   A. X-rays
   B. α-rays
   C. β-rays
   D. γ-rays

6. In a photoelectric effect monochromatic light is incident on a metal surface. If the incident light of twice the intensity but of same wavelength the kinetic energy of the emitted electron_______________?

   A. Becomes double
   B. Remains same
   C. Becomes half
   D. First increases then decrease because of the curvilinear graph

7. Wavelength of X-rays falling at glancing angle of 30? on a crystal with atmic spacing 2 x 10-10 for the fist order diffraction is________________?

   A. 4 x 10-10 m
   B. 2 x 10-10 m
   C. 0.02×10-10m
   D. 20×10-10m

8. Why gamma rays are used to kill bacteria to sterilize surgical equipment etc ?

   A. Chargeless
   B. Massless
   C. Highly penetrating
   D. All of above

9. Which of the following will be a better shield against gamma rays ?

   A. Ordinary water
   B. Heavy water
   C. Lead
   D. Aluminum

10. The minimum wavelength of X-rays can further be reduced by _______________?

    A. Reducing the pressure or cooling the target
    B. Increasing the temperature of the filament.
    C. Using a target element of higher atomic number
    D. Increasing the potential difference between the cathode and the target