Surface resistance of an insulating material is reduced due to the______________?

A. Smoky and dirty atmosphere
B. Humidity in the atmosphere
C. Both (a) and (b)
D. Neither (a) nor (b)

In conductors conduction of electricity takes place due to movement of_______________?

A. Electrons only
B. Positive ions only
C. Negative ions only
D. Positive and negative ions

Effect of moisture on the insulating materials is to________________?

A. decrease dielectric constant
B. decrease dielectric strength
C. decrease insulation resistance
D. increase dielectric loss

The forbidden gap in an insulator is________________?

A. Large
B. Small
C. Nil
D. Any of the above

If the resistance of a conductor does not vary in accordance with Ohm’s law it is known as____________?

A. Non-linear conductor
B. Reverse conductor
C. Bad-conductor
D. Non-conductor

Due to which of the following fact, in India, aluminium is replacing copper ?

A. Aluminium is more ductile and malleable than copper
B. Aluminium is available in plenty, cheaper and lighter than copper
C. Aluminium has lower resistivity than that of copper
D. Aluminium has less temperature co-efficient than copper

Selenium is __________ semiconductor?

A. Extrnisic
B. Intmisic
C. N-type
D. P-type

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

Spark plug makes use of which of the following materials for insulation ?

A. Porcelain
B. Slate
C. Asbestos
D. Glass

___________ has the best damping properties?

A. Diamond
B. High speed steel
C. Mild steel
D. Cast iron