If the band gap between valence band and conduction band in a material is 5.0 eV, then the material is
Options
(a) semiconductor (b) good conductor (c) superconductor (d) insulator
Correct Answer:
insulator
A very small circular loop of radius a is initially (at t=0) coplanar and concentric with a much larger fixed circular loop of radius b. A constant current I flows in the larger loop. The […]
The de-Broglie wavelength of an electron is the same as that of a 50 KeV X-ray photon. The ratio of the energy of the photon to the kinetic energy of the electron is (the energy […]
Four cells, each of emf E and internal resistance r, are connected in series across an external resistance R. By mistake one of the cells is connected in reverse. Then, the current in the external […]
The ionisation energy of hydrogen is 13.6 eV. The energy of the photon released when an electron jumps from the first excited state (n=2) to the ground state of hydrogen atom is
Options
Two coherent monochromatic beams of intensities I and 4I respectively, are superposed. Then, the maximum and minimum intensities in the resulting pattern are
Options
(a) 5I and 3I (b) 9I and 3I (c) […]
An object is placed 30 cm away from a convex lens of focal length 10 cm and a sharp image is formed on a screen. Now, a concave lens is placed in contact with the […]
A glass slab consists of thin uniform layers of progressively decreasing refractive indices refractive index such that the refractive index of any layer is μ-m∆μ. Here μ and ∆μ denote the refractive index of 0th […]
2017 Copyright Doctor Dreams Training Academy