Thermonic emission occurs in______________?

A. vacuum tubes
B. copper conductors
C. ferrite cores
D. transistors

The photo-electric effect occurs only when the incident light has more than a certain critical____________?
A. intensity B. speed C. frequency D. wave length...
is a negatively charged particle present in an atom______________?
A. Proton B. Neutron C. Electron D. None of the above...
Superconductors are becoming popular for use in________________?
A. generating very strong magnetic field B. manufacture of bubble memories C. generating electrostatic field D. generating regions free from magnetic field...
Overhead telephone wires are made of_____________?
A. aluminium B. steel C. ACSR conductors D. copper...
Most of the common metals have _________ structure?
A. linear B. hexagonal C. orthorhombic D. cubic...
In graphite, bonding is____________?
A. covalent B. metallic C. Vander Waals D. Vander Waals and covalent...
Steel wire is used as____________?
A. overhead telephone wire B. earth wire C. core wire of ACSR D. all of the above...
Copper, even though costly, finds use in the windings of electrical machines because_____________?
A. copper points offer low contact resistance B. copper can be easily soldered and welded E. copper windings are less bulky and the machines become compact D. all of the above...
The forbidden gap in an insulator is________________?
A. large B. small C. nil D. any of the above...
Selenium is __________ semiconductor?
A. extrnisic B. intmisic C. N-type D. P-type...