RRB JE Electrical solved question paper 2015 | RRB JE Electrical

Answer.2. 10

Explanation:-

The octal number system has a base of eight, meaning that it has eight possible digits: 0, 1, 2, 3, 4, 5, 6, and 7.

Octal to decimal conversion: Following procedure is adapted to convert a given octal integer into its equivalent decimal number:

Write the octal number, i.e., all its digits in a row. Now 12 in base 8 is equal to each digit multiplied with its corresponding 8ⁿ:

12₈ = 1 × 8¹ + 2 × 8⁰  = 10₁₀ 

Answer.3. All input are low

Explanation:-

NOR gate

The NOR gate has two or more input signals but only one output signal. All inputs must be low and get a high output. In other words, the NOR gate recognizes only the input words whose bits are all 0S.

NOR means NOT OR, i.e. the OR output is NOTed. So, a NOR gate is a combination of an OR gate and a NOT gate.
Fig shows the logical structure of the NOR gate which is an OR gate followed by a NOT gate. Therefore, the final output is NOT the OR of the inputs. A small invert bubble has been added to the OR symbol to form the NOR symbol.

Answer.3. Active filter

Explanation:-

In electrical engineering, a filter is a frequency-selective circuit that passes a specified band of frequencies and blocks or attenuates signals of frequencies outside this band. These signals are usually voltages.

Passive Filter:- Filters that employ only passive elements such as capacitors, inductors, and resistors are called passive filters. In low-frequency applications (up to 100kHz), passive filters are generally constructed using simple RC (Resistor-Capacitor) networks, while higher frequency filters (above 100kHz) are usually made from RLC(Resistor-Inductor-Capacitor) components.

Active Filter:- When we apply a voltage across them or pass a current through them, they react in a certain orderly way according to simple rules, such as Ohm’s Law. They do not amplify the input signal, therefore, their output level is always less than the input.

Filters that make use of the properties of op-amps in addition to resistors and capacitors are called active filters such as Amplifier, transistors. Active components, such as transistors and op-amps, behave in a more complicated way and can have an amplifying effect on the current passed through them and the voltage applied across them.

Hence the passive filter networks use only passive elements such as resistors, inductors, and capacitors. On the other hand, active filter circuits use active elements such as op-amps, transistors along with resistors, inductors, and capacitors.

Both active and passive filters are used in electronic circuits. However, active filters offer the following advantages over passive filters:

1. The flexibility of gain and frequency adjustment: Since op-amps can provide a voltage gain, the input signal in  the active filters is not attenuated as it is in passive filters. It is easy to adjust or tune active filters.
2. No loading effect: Because of the high input resistance and low output resistance of op-amps, active filters do not cause loading of the input source or the load.
3. Cost and size: Active filters are less expensive than passive filters because of the availability of low-cost op-amps and the absence of inductors.
4.  Parasitics: Parasitics are reduced in active filters because of their smaller size.
5.  Digital integration: Analog filters and digital circuitry can be implemented on the same IC chip.
6. Filtering functions: Active filters can realize a wider range of filtering functions than passive filters.
7. Gain: An active filter can provide gain, whereas a passive filter often exhibits a significant loss.

Answer.2. Depletion region

Explanation:-

• A PN junction is said to be formed only when a bonding force is created between p-type and n-type semiconductors.
• Ionization within a P-N junction causes a layer on each side of the barrier called the depletion layer.
• The depletion layer is also called the “space charge region” or “transition region”.
• The depletion layer is created due to the diffusion of majority carriers across the junction.
• In the depletion layer, mobile charge carriers (electrons and holes) are zero.
• The depletion layer consists of ions and covalent bonds.
• The depletion layer consists of immobile charged particles.
• The depletion layer consists of negative and positive charges (ions) on either side of the junction.
• The depletion layer consists of negative ions (acceptor ions) on the p-side and positive ions (donor ions) on the n-side.
• The depletion layer opposes majority carriers in crossing the junction.
• The depletion layer does not oppose minority carriers in crossing the junction.

Answer.2. Round specimen of ductile metals

Explanation:-

Fracture

When a metallic body is subjected to stress it withstands the applied stress. When the body is no longer able to withstand the applied stress it starts cracking. Cracking goes through two stages viz. crack initiation and crack propagation. The formation of crack, due to the release of stress in a metallic body that ultimately results in the separation of the body into two or more parts, is known as a fracture. There are different types of fracture viz. ductile, brittle, fatigue, etc. 

DUCTILE  FRACTURES

Fractures can be classified broadly as ductile fractures and brittle fractures. A ductile fracture is associated with considerable plastic deformation. An appreciable amount of gross plastic deformation in the form of change in dimension (increased length or local decrease in cross-section) can actually be observed in the case of a ductile fracture. A typical cup and cone fracture of a ductile metal as observed in a tensile test is an example of a ductile fracture.  A ductile fracture is characterized by a fibrous fracture surface with a prominent shear lip. Thus a typical cup and cone fracture of a moderately ductile metal, a rupture following drawing of a highly ductile metal viz. gold or lead to a point and mere separation of metal by 45° shear are all examples of ductile fractures.

Answer.1. Compressibility

Explanation:-

The liquid limit of soil is the percentage of water content at which the soil passes from the plastic state to the liquid state or the Liquid limit indicates how much water the soil can hold without getting into the “liquid” state. The compressibility of soil is indicated by liquid limit, i.e. the compressibility of the soil generally increases with an increase in the liquid limit.

Answer.2. Bending moment only

Explanation:-

Beams with large depths in relation to spans are called deep beams. A simply-supported beam is classified as deep when the ratio of its effective span L to overall depth D is less than 2. Continuous beams are considered as deep when the ratio L/D is less than 2.5. 

A beam, whether deep or conventional, is always designed for bending moments. The moment of resistance corresponding to the bending moment is directly proportional to the moment of inertia. So for a greater moment of resistance on which the bending moment shall act, we have to provide a greater moment of inertia which can be achieved only by providing depth more than that of width. That’s why deep beams are designed.

Answer.4. Stress in slab base

Explanation:-

Stress in the slab base is independent of yield stress as permissible stress for steel members.

Answer.3. Cohesion being greater than the adhesion

Explanation:-

Capillary is a phenomenon by which a liquid (depending upon its; specific gravity) rises into a thin glass tube above or below its general level.”The rise of the liquid surface is known as capillary rise and the fall of the liquid surface is called capillary depression.

Cohesion refers to the attraction between particles of the same substance. That is, it is the intermolecular force between molecules of the liquid. It is maximum in solids, lesser in liquids, and least in gases.

Adhesion is the attraction between particles of different substances. Adhesion is seen in the ability of water to rise in thin tubes by capillary action. The Force of adhesion is different for different substances. For example, gum has greater adhesive force for a solid surface than water. When we pour water on a glass plate, the plate becomes wet because of the adhesive force between the molecules of glass and water.

When water spreads out and wets a glass surface the force of adhesion is greater than the force of cohesion. If we put mercury on a glass surface it does not behave in the same way as water. Mercury forms small droplets when it is poured onto the glass. The mercury molecules are attracted more strongly to other mercury molecules than they are to the glass. The force of cohesion is greater than the force of adhesion and we say that mercury is hydrophobic (water-hating).

Practical Examples of Cohesion e and Adhesive Forces. 

(a) The ink sticks on paper. It is because the adhesive force between ink and paper is greater than the cohesive force of ink molecules.

(b) Water wets the glass. It is because the adhesive force between water molecules and glass molecules is greater than the force of cohesion between water molecules.

(c) Mercury does not wet the glass because the adhesive force between mercury molecules and glass molecules is less than the cohesive force between mercury molecules.

(d) We are able to write on the blackboard with a piece of chalk because the adhesive force between chalk molecules and wood molecules is much greater than the cohesive force between chalk molecules.

Answer.2. Aligning the chain in a strength line between two extremities

Explanation:-

Ranging is the process of aligning the chain in a strength line between two extremities