RRB JE ECE (CBT II) Mock Test- 8 - Electronics and Communication Engineering (ECE) MCQ

A Colpitts oscillator uses two capacitors in place of the two inductors of a Hartley oscillator.
Colpitts oscillator

Hartley oscillator

WAN is a Wide Area Network, WANs are typically used to connect comparatively large geographical area such as; a state, a country, a continent, the Internet WANs can span over a range of huge area of a 100,000-kilometre radius >WANs have its ownership and management is distributed, it cannot be handled at the individual level

A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus etc.

LANs can span over a limited range i.e. of 1 km in radius MAN is Metropolitan Area Network and is used to connect two or more LANs in a common geographic area: say a city or a group of buildings MANs can span in the range of 5 to 50 kilometres in diameter.

Total resistance = 10/50 x 10^-6 = 200 kΩ

• V is, is a representation of the Combined Gas Law.
• This law is obtained by combining Gay-Lussac's Law, Boyles's Law and Charles's Law.
• Boyle's Law is represented as P ₁V₁ = P₂V2, P is pressure and V is the volume. 
• Charles' Law is represented as V₁T₂ = V₂T_1,  V is the volume whereas T is the temperature. 
• Graham's Law states that the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles. 

All the factors such as Bandwidth, free space loss and radiated power affects the Carrier to Noise ratio:
The Carrier to noise ratio is related to the parameters by the equation:

A virus is a program that can infect other programs by modifying them to include a possibly evolved copy of itself.

Some of the common types of viruses are:

Boot Sector Virus: A boot sector virus displaces the boot record and copies itself to the boot sector i.e. where the program to boot the machine is stored. 

File Virus: A file virus generally attacks executable files. 

Macro Virus: The virus infects an important file of MS word. As soon as the application is opened the virus gets activated. It damages the formatting of documents and may not even allow the editing or saving of documents 

Trojan Horse: It is a code hidden in games or spreadsheets. Its main objective is to cause harm to the data. They can create a bad sector on the disk, destroy file allocation tables and cause the system to hang.

Worm: It is a program capable of replicating itself on a computer network. It travels from one computer to another across communication links. They generally disrupt the routine services. 

Bridges are used to divide larger networks into smaller sections
They do this by sitting between two physical network segments and managing the flow of data between the two
By looking at the MAC address of the devices connected to each segment, bridges can elect to forward the data (if they believe that the destination address is on another interface) or block it from crossing (if they can verify that it is on the interface from which it came)

Hubs
Hubs work at the first or Physical Layer
It links all the devices connected to it and forms a single network
Each device that directly connects to the hub uses a port on the hub
When one device sends out a message to another device, the hub does not decide where the message goes; It just repeats the message to all the ports
Each device needs to decide whether this message is for itself or for others
Switch:
Switches operate at the Data Link or second layer
Switches are “intelligent” hubs
Switches can remember which ports are connected to which devices
When a switch receives a packet (data), it resends that packet directly to the correct port
Router:
Routers are on the third layer, the Network layer
They are used to connect networks together
The Internet consists of many interconnected routers
Using a network protocol, like TCP/IP, a router can intelligently move data from one network to another

The potential difference is defined as work done per unit charge.

This implied that, V = W/q

Where V is Potential Difference; W is Work Done; q is charge

Or, W= V× q

= 2×10

= 20 Joules.

Vacuum triodes were used for amplification purpose before the discovery of transistors

A triode is a vacuum tube with three electrodes which are a cathode, Anode and a control grid

Vacuum diodes were used in place of p-n junction diodes earlier

When electric current flows through a resistor some of the energy is transferred to heat energy. This results in the resistor heating up.

A resistor in a circuit becomes very hot and starts to burn. This is because the resistor is dissipating too much power

Power = I²R

• In a semiconductor, the charged carriers are both electrons and holes
• In Intrinsic Semiconductors, at room Temperature, the valence band is completely filled and conduction band is completely empty
• Intrinsic Semiconductor is Insulators at room Temperature
• In an n-type Semiconductor, thermal energy is not sufficient to excite electrons from valence Band to Conduction Band
• But Energy is sufficient to excite electrons from donor to conduction Band
• Hence in n-type semiconductor valence Band is filled But conductivity is not Zero due to thermally excited carriers from donor level

Hence, the correct option is (D)

The dead organic matter of plant or animal is called as detritus. While a part of it remains on the soil surface as litter, the other part enters the soil. Many animals such as protozoan ‘s, nematodes, insects etc. depend on detritus and hence they are called as detrivores.

From Hall Effect we have V _H = BI/_pW
Where hall coefficient is given as R_H = 1/p = 1/ne
Hall Effect can be used to measure the carrier concentration and type of semiconductor

There are two types of rechargeable batteries used in emergency lights:

1) Lead-Acid batteries

2) Nickel-Cadmium batteries

Animals produce methane during the digestion process. Currently, around 20 percent of the world's methane emissions comes from ruminants. Studies revealed that ruminants, which include cows and sheep, release more methane into the environment than kangaroos.

Hartley Oscillator:
The tank circuit of Hartley Oscillator is shown:

Advantages

• Instead of two separate coils L1 and L2, a single coil of bare wire can be used and the coil grounded at any desired point along it.
• By using a variable capacitor or by making core movable (varying the inductance), frequency of oscillations can be varied.
• Very few components are needed, including either two fixed inductors or a tapped coil.
• The amplitude of the output remains constant over the working frequency range.

Disadvantages

• It cannot be used as a low frequency oscillator since the value of inductors becomes large and the size of the inductors becomes large.
• The harmonic content in the output of this oscillator is very high and hence it is not suitable for the applications which require a pure sine wave.

Applications

• The Hartley oscillator is to produce a sine wave with the desired frequency
• Hartley oscillators are mainly used as radio receivers
• The Hartley oscillator is Suitable for oscillations in RF (Radio-Frequency) range, up to 30MHZ

A Zener voltage regulator is simpler circuit than series voltage regulator since transistors are required in series voltage regulator.

Positive Feedback is preferred in oscillators as it provides positive gain to the system. It will improve the overall system gain. For oscillator the gain should be at maximum to have sustained oscillations.

Diode is a nonlinear device because these device does not have a linear relationship between current and voltage.

Example: gas diode, tunnel diode electric arc, inductor etc.

Y = C(XOR) R

C = A(AND)B = AB

B = P OR Q = (P + Q)

C = A.B = (P + Q) (P' + Q')

= PQ' + QP'

C = (P EXOR Q)

Y = C XOR R

= P EXOR Q EXOR R

Most of the refraction occurs at the cornea. Lens provides only the finer adjustment
Different parts of the eyes and their functions are shown in the table:

Concept:

When circuit is excited by multiple sources, use superposition theorem

Therefore to determine output voltage.

Case 1: only v₁ is acting:

Case 2: only v₂ is acting

Total Output Voltage

V₀ = V₀₁ + V₀₂

= 2V₂ - 3V₁

• In the ongoing World Cadet Wrestling competition in Sofia, Bulgaria, Indian wrestler Sonam Malik won Gold in 65kg category.
• She beat Binbin Xiang 7-1 in the final.
• Wrestlers in under 18 categories are competing for a total of 30 gold medals -- 20 out of them for men’s events in Greco-Roman, and freestyle wrestling and 10 others in the women’s categories.

The Ah capacity of a lead-acid battery depends on following factor:

• The number and size of plates used.
• The rate of discharging of a cell, if discharging rate is kept high, then its capacity is reduced.
• The quantity and density of electrolyte present in the cell
• Temperature of the cell
• In order to increase the Ah capacity of a lead-acid battery a greater number of plates are to be used

Food Chain is a diagram that shows how food energy moves from one organism to another in a given environment. In other words, it is the chronological order of who eats whom in a biological community.

Aquatic food chain:

Phytoplankton → Zooplankton → Small Fish → Large Fish → Whale

Phytoplankton: A mix of algae, the primary producer

Zooplankton: Small floating elements consuming the phytoplankton, the primary consumer

We can classify the instruments into two types

Absolute Instruments:

• These instruments give the magnitude of the quantity under measurements in terms of physical constants of the instrument
• There is no necessity of calibrating or comparing with other instruments
• Tangent Galvanometer and Rayleigh’s current balance are example of this class

Secondary Instruments:

• These instruments are so constructed that the quantity being measured can only be measured by observing the output indicated by the instrument
• These instruments are calibrated by comparison with an absolute instrument or any other secondary instrument which has already been calibrated against an absolute instrument
• A voltmeter, a glass thermometer and a pressure gauge are typical examples of secondary instruments

Working with absolute instruments for routine work is time consuming. Therefore, secondary instruments are most commonly used. Absolute instruments are seldom used except in standard institutions and laboratories while secondary instruments find usage almost in every sphere of measurement.

Null character is used to terminate the string in C.

• 8051 microcontroller consists of four register banks, such as Bank 0, Bank 1, Bank 2, Bank 3 which are selected by the PSW (Program Status Word) register.
• 8051 has 32 general-purpose registers and the size of each register is 8-bit.
• It has two 16-bit registers and they are data pointer (DTPR) and the program counter (PC).

Important:

In an 8051 microcontroller,

• Internal RAM (data memory) - 128 bytes
• Internal memory (code memory) - 4 kB
• Timer/counter - 2
• No. of interrupt - 5
• I/O pins - 32
• Serial port - 1

V = -20 sin ωt

Apply KCL at node B

I₀ = -7sin ωt