SSC JE Electrical 2019 with solution SET-2
While estimating the overhead lines, if the number of poles required is 14, then what is the estimated number of earth sets required?
While estimating the overhead lines, the first and last pole is always earth connected and after every 3rd electrical pole, the fourth pole is earthed. Therefore, the approximate number of required ground set = 4
⇒ The electric potential at a point is defined as the work done in bringing the unit positive charge ( +1C) from infinity to that point. The work done is independent of the path taken. Its unit is Volt (V). ⇒ Potential Difference (pd or V) is a measure of the difference in charge between two points in a conductor. Its unit is Volt (V). ⇒ The difference in charge produced by the battery is stored in the battery as electrical potential energy and is called electromotive force (shortened to emf). Electromotive force is also measured in volts. Its unit is Volt (V). ⇒ Electric flux is a measure of how much the electric field vectors penetrate through a given surface. The SI unit of electric flux is N.m2/C. Electrical potential, Potential difference, Electromotive force has the same SI unit i.e Volt (V). Hence Electric flux is alike from others.
The resistivity of iron at 20°C is 9.71 × 108 The resistivity of silver at 20°C is 1.59 × 108 The resistivity of Glass at 20°C is 1.10 × 109 The resistivity of nichrome at 20°C is 100 × 108 Hence silver is the least resistive material in the given option.
The transformers which are particularly designed to provide electrical isolation between primary and secondary circuits, without a change in voltage and current level are called isolation transformers. The turns ratio of such isolation transformers is 1:1 i.e N1 and N2. Hence, isolation transformers are also called 1:1 transformers. The isolation transformer greatly reduces any voltage spikes that originate on the supply side before they are transferred to the load side. Some isolation transformers are built with a turns ratio of 1:1. A transformer of this type has the same input and output voltages and is used for the purpose of isolation only. The main function of the isolation transformer is to reduce the voltage spike before it reaches the load.
EXAMIANS