A. Sand on rails
B. Dew on rails
C. Oil on the rails
D. both B. and C.
Related Mcqs:
- Due to which of the following co-efficient of adhesion improves ?
A. Rust on the rails
B. Dust on the rails
C. Sand on the rails
D. All of the above - If the co-efficient of adhesion on dry rails is 0.26, which of the following could be the value for wet rails ?
A. 0.3
B. 0.26
C. 0.225
D. 0.16 - Co-efficient of adhesion is________________-?
A. high in case of D.C. traction than in the case of AC. traction
B. low in case of D.C. traction than in the case of AC. traction
C. equal in both AC. and D.C. traction
D. any of the above - The value of co-efficient of adhesion will be high when rails are_________________?
A. greased
B. wet
C. sprayed with oil
D. cleaned with sand - The normal value of adhesion friction is______________?
A. 0.12
B. 0.25
C. 0.40
D. 0.75 - When a bogie negotiates a curve, reduction in adhesion occurs resulting in sliding. Thus sliding is acute when_______________?
A. wheel base of axles is more
B. degree of curvature is more
C. both A. and B.
D. none of the above - If the power level of an amplifier reduces to half, the db gain will fall by___________?
A. 5 db
B. 2 db
C. 10 db
D. 3 db - For three-phase induction motors which of the following is the least efficient method of speed control ?
A. Cascade control
B. Pole changing
C. Rheostat control
D. Combination of cascade and pole changing - Series motor is not suited for traction duty due to which of the following account ?
A. Less current drain on the heavy load torque
B. Current surges after temporary switching off supply
C. Self relieving property
D. Commutating property at heavy load - The leakage current across a pn junction is due to________________?
A. Minority carriers
B. Majority carriers
C. Junction capacitance
D. None of the above
