EE MCQ

SSC JE Electrical 2019 with solution SET-1
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The ratio of average energy demand to maximum demand during a specific period in

The ratio of average energy demand to maximum demand during a specific period is called the load factor.

Load Factor = Average Load/Maximum Demand

Related Question

SSC JE Electrical 2019 with solution SET-1
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Find the net capacitance of the combination in which ten capacitors of 10 μF are connected in parallel

When the capacitance is connected in series the total capacitance is given by

Ceq = C1 + C2 + C3………CN

Ceq = 10n

Ceq =10 × 10 = 100 μF

SSC JE Electrical 2019 with solution SET-1
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Z1 and Z2 are connected in series to form a load. A wattmeter’s current coil is connected in series with the load, whereas its pressure coil is connected across Z2. The wattmeter reads

As you can see from the below figure in load Z1 is connected with the only current coil. In Load Z2 both current from the current coil (CC) and voltage from voltage coil (PC) are present (Power = V × I). Hence the Wattmeter will read power consumed by Z2.

SSC JE Electrical 2019 with solution SET-1
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Two coupled coils with L1 = L2 = 0.5H have a coupling coefficient of K = 0.75. The turn ratio N1 ⁄ N2 = ?

The self-inductance is given as

L = μN2A/I

L ∝ N2

where

N is the number of turns of the solenoid

A is the area of each turn of the coil

l is the length of the solenoid

and μ is the permeability constant

L1/L2 = N21/N22

0.5/0.5 = N21/N22

N1/N2 = 1

SSC JE Electrical 2019 with solution SET-1
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In electric traction, the coefficient of adhesion is represented by

When two solid surfaces are brought into contact, a finite normal force is needed to pull the two solids apart. This force is known as the force of adhesion or simply adhesion.

The coefficient of adhesion () defined as the ratio of tractive effort required to propel the wheel of a locomotive to its adhesive weight. Adhesion traction is the friction between the drive wheels and the steel rail.

µ = Ft/W

Where

Ft = Tractive effort

W = Adhesive Weight

SSC JE Electrical 2019 with solution SET-1
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The laws involved in the expression e = −dφ/dt are

Faraday’s 1st laws of electromagnetic induction tell us about the condition under which an e.m.f. is induced in a conductor or coil a when the magnetic flux linking a conductor or coil changes.

Faraday’s 2nd laws of electromagnetic induction give the magnitude of the induced e.m.f in a conductor or coil and may be stated as:

The magnitude of the e.mf induced in a conductor or coil is directly proportional to the rate of change of magnetic flux linkages.

Suppose a coil has N turns and magnetic flux linking the coil increases (i.e. changes) from φ1 Wb to φ2 Wb in t seconds. Now, magnetic flux linkages mean the product of magnetic flux and the number of turns of the coil.

N = e dφ/dt

Lenz Law:- Lenz’s law states: the direction of the induced e.m.f. is such as to oppose the change producing it. Therefore, the magnitude and direction of induced e.m.f. should be written as :

N = −e dφ/dt