Question: ___________ has the best damping properties?

• 1. Diamond
• 2. High speed steel
• 3. Mild steel
• 4. Cast iron

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

• 1. Porcelain
• 2. Slate
• 3. Asbestos
• 4. Glass

Question: The photo-electric effect occurs only when the incident light has more than a certain critical____________?

• 1. intensity
• 2. speed
• 3. frequency
• 4. wave length

Question: Selenium is __________ semiconductor?

• 1. extrnisic
• 2. intmisic
• 3. N-type
• 4. P-type

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

• 1. Aluminium is more ductile and malleable than copper
• 2. Aluminium is available in plenty, cheaper and lighter than copper
• 3. Aluminium has lower resistivity than that of copper
• 4. Aluminium has less temperature co-efficient than copper

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

• 1. non-linear conductor
• 2. reverse conductor
• 3. bad-conductor
• 4. non-conductor

Question: The forbidden gap in an insulator is________________?

• 1. large
• 2. small
• 3. nil
• 4. any of the above

Question: Effect of moisture on the insulating materials is to________________?

• 1. decrease dielectric constant
• 2. decrease dielectric strength
• 3. decrease insulation resistance
• 4. all of the above

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

• 1. electrons only
• 2. positive ions only
• 3. negative ions only
• 4. positive and negative ions

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

• 1. smoky and dirty atmosphere
• 2. humidity in the atmosphere
• 3. both (A) and (b)
• 4. neither (A) nor (b)