Question: The braking retardation is usually in the range__________________?

• 1. 0.15 to 0.30 km phps
• 2. 0.30 to 0.6 km phps
• 3. 0.6 to 2.4 km phps
• 4. 3 to 5 km phps

Question: Which of the following methods is used to control speed of 25 kV, 50 Hz single phase traction ?

• 1. Reduced current method
• 2. Tap changing control of transformer
• 3. Series parallel operation of motors
• 4. All of the above

Question: The rate of acceleration on suburban orurban service is in the range_________________?

• 1. 0.2 to 0.5 km phps
• 2. 1.6 to 4.0 km phps
• 3. 5 to 10 km phps
• 4. 15 to 25 km phps

Question: _______________watt-hours per tonne km is usually the specific energy consumption for suburban services?

• 1. 15—20
• 2. 50—75
• 3. 120—150
• 4. 160—200

Question: Low resistivity materials are used in__________?

• 1. transformer, motor and generator windings
• 2. transmission and distribution lines
• 3. house wiring
• 4. all above applications

Question: Which of the following materials is used for making coils of standard resistances ?

• 1. Copper
• 2. Nichrome
• 3. Platinum
• 4. Manganin

Question: Copper, even though costly, finds use in the windings of electrical machines because_____________?

• 1. copper points offer low contact resistance
• 2. copper can be easily soldered and welded
• 3. copper windings are less bulky and the machines become compact
• 4. all of the above

Question: Which of the following is an advantage of stranded conductor over equivalent single conductor ?

• 1. Less liability to kink
• 2. Greater flexibility
• 3. Less liability to break
• 4. All of the above

Question: Substances whose specific resistance abruptly decreases at very low temperature are called___________?

• 1. insulators
• 2. conductors
• 3. semiconductors
• 4. superconductors

Question: is the property of absorbing moisture from atmosphere_____________?

• 1. Solubility
• 2. Viscosity
• 3. Porosity
• 4. Hygroscopicity