Which of the following is the poorest conductor of electricity ?
(A) Carbon
(B) Steel
(C) Silver
(D) Aluminium
Constantan contains_______________?
(A) silver and tin
(B) copper and tungsten
(C) tungsten and silver
(D) copper and nickel
The structure sensitive property of a super conductor is______________?
(A) critical magnetic field
(B) transition temperature
(C) critical current density
(D) none of the above
At transition temperature the value of critical field is____________?
(A) zero
(B) negative real value
(C) positive real value
(D) complex value
By increasing impurity content in the metal alloy the residual resistivity always_____________?
(A) decreases
(B) increases
(C) remains constant
(D) becomes temperature independent
The coils of D.C. motor starter are wound with wire of_______________?
(A) copper
(B) kanthal
(C) manganin
(D) nichrome
Thermonic emission occurs in______________?
(A) vacuum tubes
(B) copper conductors
(C) ferrite cores
(D) transistors
A good electric contact material should have all of the following properties except_____________?
(A) high resistivity
(B) high resistance to corrosion
(C) good thermal conductivity
(D) high melting point