The melting point of Eureka is 1221 to 1300 °C The melting point of Kanthal is 1,425 °C The melting point of Nichrome is 1400 °C The melting point of Graphite is 3,600°C Hence Eureka has the least range of temperature.
The combined inductance of two coils connected in series L = L1 + L2 + 2M In series adding case L1 + L2 + 2M = 0.6 H ——–(1) In series opposing case L1 + L2 − 2M = 0.1 H ——–(2) Subtracting eqn (2) from eqn (1) we get 4M = 0.5 H M = 0.125 H Let L1 = 0.2 H (since the coil when isolated, its self-inductance is 0.2 H) Putting the value of M & L1 in equation (2) 0.2 + L2 + 2 ×0.125 = 0.06 0.2 + L2 = 0.35 L2 = 0.15 H
A choke coil is simply a coil having a large inductance, but a small resistance. A device that can regulate the current in an A.C. circuit without much loss of energy is called as ‘choke coil’.
Average speed:- The distance covered between two stops divided by the actual time of the run is known as average speed. Average speed = (Distance between stops)/(Actual time of run) Schedule speed:- It is defined as the ratio of distance covered between two stops and the total time of run including the time of the stop. Schedule speed = (Distance between stops) /(Actual time of run + Stop time) This shows that schedule speed is always smaller than the average speed. The difference is large in the case of urban and suburban services and is negligibly small in the case of main-line service.
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