X-ray are:
A. of unknown nature
B. high energy electrons
C. high energy photons
D. radio isotop
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
Excited atoms return to their ground state in:
A. 10-10s
B. 10-8s
C. 10-6s
D. 10-9s
Michelson calculated the speed of light using the instruments:
A. spectrometer
B. galvanometer
C. interferometer
D. none of these
The function of collimeter in spectrometer is:
A. to produce parallel beams of light
B. to filter the light rays
C. to make them
D. no function
Magnification of the astronomical telescope is:
A. fo+fe
B. fo/fe
C. fe/fo
D. (1+fo/fe)L/fo
The value of critical angle for glass is:
A. 42°
B. 47°
C. 52°
D. 50°
Dioptre power of an concave lens of 10 cm focal length is:
A. 10 dioptre
B. 10 dioptre
C. 1 / 10 dioptre
D. 1 / 10 dioptre
The minimum distance between an object and its real image in a convex lens is:
A. 2 f
B. 2.5 f
C. 3f
D. 4f
In multimode step index fibre the refractive index of core and cladding is:
A. same
B. different
C. zero
D. different with refractive index of core higher than cladding
