A. Holes can exist in certain semiconductors only
B. Holes can exist in any material including conductors
C. Holes may constitute an electric current
D. Holes can be considered as a net positive charge
Related Mcqs:
- The current due to electron flow in conduction band is the hole current in valence band?
A. equal to
B. less than
C. greater than
D. any of the above - Which of the following materials is preferred for transmitting electrical energy over long distance ?
A. Copper
B. Aluminium
C. Steel reinforced copper
D. Steel reinforced aluminium - In thermocouples which of the following pairs is commonly used ?
A. Copper-constantan
B. Aluminium-tin
C. Silver-German silver
D. Iron-steel - 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 - Due to which of the following reasons aluminium does not corrode in atmosphere ?
A. Aluminium is a noble metal
B. Atmospheric oxygen can only diffuse very slowly through the oxide layer which is formed on the surface of aluminium
C. No reaction with oxygen occurs ft Any of the above - Which of the following are non-conductors of electricity?
A. Non-metal solids except carbon
B. Air and most other gases
C. Pure water and liquids in general except mercury
D. All of the above - Which of the following material is not a semiconductor ?
A. Silica
B. Germanium
C. Selenium
D. Gallium-arsenide - Which of the following high resistance materials has the highest operating temperature ?
A. Kanthal
B. Manganin
C. Nichrome
D. Eureka - Due to which of the following reasons copper and aluminium are not used for heating elements ?
A. Both have great tendency for oxidation
B. Both have low melting point
C. Very large length of wires will be required
D. All of the above - Which of the following is a semiconductor material ?
A. Phosphorous
B. Rubber
C. Silicon
D. Aluminium
