EE MCQ

SSC JE Electrical 2019 with solution SET-2
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The number of valence electrons of P and Si are respectively?

Phosphorus (P) has 15 electron i.e 2,8,5. Hence the number of electron in its outermost orbit is 5.

Silicon (Si) has 14 electron i.e 2,8,4. Hence the number of electrons in its outermost orbit is 4.

Related Question

SSC JE Electrical 2019 with solution SET-2
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The combined inductance of two coils connected in a series is 0.6H and 0.1H, depending on the relative directions of the currents to the coils. If one of the coils when isolated has a self-inductance of 0.2 H, then calculate the natural inductance?

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

SSC JE Electrical 2019 with solution SET-2
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Four statements are given below. Identify the correct statement?

**Basic logic gates**: Basic logic gates are the building blocks of digital circuits that perform logical operations such as AND, OR, and NOT, on the binary inputs. Basic gates are mainly used in the fabrication of digital systems and are called integrated circuits (ICs).

**Derived logic gates**: Derived logic gates arc those logic gates that perform logical operations on the binary inputs with the help of two or more basic logic gates. A combination of AND, OR, and NOT are called derived gates. NAND, NOR, XOR, and XNOR are such a combination of AND, OR, and NOT gates.**Exclusive OR (XOR) Gate**

A gate that identifies the odd number of 1’s in the combination of the inputs is called the XOR gate. It is a functional combination of NOT, AND, and OR gates.

SSC JE Electrical 2019 with solution SET-2
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In the salient pole of the phase synchronous machine, the rotor will have

The rotor of the synchronous machine carries a field winding that is supplied with d.c. through two slip rings by a separate d.c. source. Synchronous Rotor construction is of two types, namely :

Salient (or projections) pole type.

Cylindrical type (or non-salient pole type)**Salient-pole rotor:**-

In this type, salient poles are mounted on a large circular steel frame which is fixed to the shaft of the alternator.

The rotors of salient-pole rotor machines have concentrated winding on the poles and a nonuniform air gap.

Salient pole generators have a large number of poles. sometimes as many as 50, and operate at lower speeds.

The synchronous generators in hydroelectric power stations are of the salient pole type and are driven by water turbines.

The rotors are shorter axial length but have a large diameter.

SSC JE Electrical 2019 with solution SET-2
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When capacitors are connected in series across DC voltage then_____

When voltage is applied across the capacitor one plate becomes negatively charged with electrons leaving the battery. At the same time, electrons leave the other plate to resupply the battery, leaving that plate positively charged. This effect is called polarisation. The current flows until the charge across the capacitor is equal to the battery emf, at which point everything stops.

In series connections, the same charging current flows through all capacitors as soon as a voltage is applied. Hence in a series connection same current flows through each capacitor.