RRB JE Electrical (CBT II) Mock Test- 9 - Electrical Engineering (EE) MCQ

Output will be rectified half wave,then

Taking that the pf of the load is improved ( say from 0.7 lag to 0.85 lag) for the same real power P, then the magnitude of the line current will decrease, decreasing the line losses. So transmission efficiency will improve.

Then by using the following Ohm’s Law equations:

The relative permeability (μ_r) of a substance is the ratio of magnetic permeability (μ) of the substance to
the permeability of free space (μ₀)
μ_r = μ/μ₀
Hence, it is a dimensionless quantity and is equal to 1 for vacuum

The wattmeter measures average power

• Annealing is one of the major processes in the manufacture of glass.
• It is a controlled slow cooling process of heat treatment of glass.
• It helps in strengthening the glass and relieving the stress.

A fractional-horsepower motor (FHP) is an electric motor with a rated output power of 746 Watts or less.

There is no defined minimum output. However, it is generally accepted that a motor with a frame size of less than 35 mm square can be referred to as a micro-motor.

An induction type meter consists of two electromagnets, called shunt magnet and series magnet of laminated construction.

A coil having a large number of turns of fine wire is wound on the middle limb of shunt magnet. This coil is known as voltage coil or pressure coil and it is connected across the supply mains. It has many turns and is arranged to be as highly inductive as possible. This causes the current and therefore the flux, to lag the supply voltage by nearly 90°.
An adjustable copper shading rings are provided on the central limb of the shunt magnet to make the phase angle displacement between the magnetic field set up by shunt magnet and the supply voltage is approximately 90°.
The series electromagnet is energized by a coil which is known as current coil and it is connected in series with the load so that it carries the load current. The flux produced by this magnet proportional to and in
phase with the load current.
The moving system essentially consists of a light rotating aluminium disk mounted on a vertical spindle or shaft. The fluxes produced by shunt and series magnet induce eddy currents in the aluminium disc. The interaction between these two magnetic fields and eddy currents set up a driving torque in the disc.
As in energy meter instrument, we have two fluxes and two eddy currents and therefore two torques are produced by
(i) First flux interacting with eddy current produced by second flux and
(ii) Second flux interacting with eddy currents generated by the first flux
Maximum torque is produced when the phase angle between these two fluxes is 90°

A fractional-horsepower motor (FHP) is an electric motor with a rated output power of 1 HP (746.9 or 746 Watts) or less.

We know that, in a series RLC circuit impedance is given by

Current flowing in the circuit is given by I=V/Z

Where, Z is impedance

R is resistance

XL is inductive reactance

XC­ ­is capacitive reactance

At resonance condition, the inductive resistance is equal to capacitive reactance.

At this condition, Z = R which is minimum value of impedance

At minimum impedance, the current flowing in the circuit is maximum

Hence both A and R are true, and R is the correct explanation of A.

The voltage induced across an inductance is proportional to the rate of change of current di/dt.
V _L = L di/dt
V _L  ∝ di/dt
For DC supply, di/dt = 0 ⇒ V_L = 0 V
For DC supply Inductors carrying steady direct currents act as effective short circuits with zero voltage across it.

Concept:

Waste to Energy (WtE) or Energy from Waste (EfW) is the process of generating energy in the form of electricity and/or heat from the primary treatment of waste, or the processing of waste into a fuel source. WtE is a form of energy recovery.

The methods by which energy can be recovered from Waste to Energy are:

• Heat
• Electricity
• Co-generation

Advantages of Waste to Energy:

• Reduction volume of waste
• Reduction of waste going to landfill sites
• Reduction of carbon emissions
• Reduction of the use of fossil fuels
• Electricity and heat can be generated from waste which provides an alternative and more environment-friendly source of energy
• The local community around EfW facilities benefits from the creation of jobs to cost effective energy

We know that,

In parallel circuit sum of the currents through each path is equal to the total current that flows from the source.

Total resistor in the circuit = 100

The value of each resistor = 1 Ω

The current in each resistor when connected in series = 1 A

Source voltage = 1 × 100 = 100 V

• If frequency of the transformer is decreased, magnetizing current in the primary of the transformer increases as it is inversely proportional to frequency and directly proportional to the applied voltage.
• This magnetizing current is used to set up flux in core of the transformer.
• If magnetizing current goes beyond certain limit, the transformer core may saturate. Therefore, it is required to reduce applied voltage along with frequency in same proportion to keep the magnetizing current same.
• This will reduce applied voltage (400/50 = 8) by 8 times and thus its KVA rating too will reduce 8 times.

• Tropical forest trees, like all green plants, take in carbon dioxide and release oxygen during photosynthesis
• Plants also carry out the opposite process known as respiration in which they emit carbon dioxide, but generally in smaller amounts than they take in during photosynthesis; The surplus carbon is stored in the plant, helping it to grow
• When trees are cut down and burned or allowed to rot, their stored carbon is released into the air as carbon dioxide
• So, the levels of carbon dioxide will increase and cause global warming

• And this is how deforestation and forest degradation contribute to the increase in greenhouse gases and hence global warming

PE lost = KE gained

KE gained = mgh

KE gained = 8*10*20

KE gained = 1600 J

KE = (1/2)mv²

1600 = (1/2)*8*v²

Solve for v

V = Square root of 400

V = 20 m/s²

Primary Memory (Main Memory): Primary memory is also known as main memory. It holds only those data and instructions on which computer is currently working. It has limited capacity and data is lost when power is switched off.
Primary memory can be divided into RAM (Random Access Memory) and ROM (Read Only Memory)

Skin effect is the tendency of an alternating electric current to become distributed within a conductor such that the current density is largest near the surface of the conductor and decreases with greater depths in the conductor.

The electric current flows mainly at the skin of the conductor, between the outer surface and a level called the skin depth. The skin effect causes the effective resistance of the conductor to increase at higher frequencies where the skin depth is smaller, thus reducing the effective cross-section of the conductor.

Aerosols are chloroform-hydrocarbon compounds released into air with force in the form of vapour. Main source of aerosols is the emission of jet planes, where fluorocarbons are used. These chlorofluorocarbons deplete the ozone layer in the higher atmosphere. These CFC ‘s has produced a hole in the ozone layer.

The breaking torque is given by

∴ N ∝ 1/d i.e speed of disc is inverse relation with the position of spindle from the permanent magnet.
If an induction type energy meter runs fast, it can be slowed by adjusting the position of braking magnet and making it move away from the centre of the disc.

Greenhouse gases are released by many different types of activities, not just the burning of fossil fuels, but also farming, deforestation and some industrial processes.

Energy sector contributes majorly towards global Warming by releasing greenhouse gases. The percentages of greenhouse gas emissions for different activities are given below.

Energy sector: Electricity and heat (24.9%), Industry (14.7%), Transportation (14.3%), Other fuel combustion (8.6%), Fugitive emissions (4%).

Agriculture sector (13.8%)

Deforestation (12.2%)

Industrial processes (4.3%)

The soil pollutants that affect the food chain and food web by killing micro-organisms and plants are pesticides.

Agricultural waste is waste produced as a result of various agricultural operations. It includes manure and other wastes from farms, poultry houses and slaughterhouses; harvest waste; fertilizer run off from fields; pesticides that enter into the water, air or soils; and salt and silt drained from fields.

A pathogen or infectious agent is a biological agent that causes disease or illness to its host.

• Microsoft Excel is the electronic spreadsheet program within the Microsoft Office suite
• An electronic spreadsheet is an application used to perform numeric calculations and to analyse and present numeric data
• In Excel, the electronic spreadsheet is called a worksheet and it is contained in a file called workbook, which has the file extension .xlsx
• Cells are the basic unit for storing data
• In any spreadsheet program such as Excel, each rectangular box is referred to as cell
• A cell is the intersection point of a column and a row
• Data entered into an Excel spreadsheet is entered into a cell
• Each cell can hold only one piece of data at a time

The mass of the earth, M = 6 × 1024 kg

The mass of the moon, m = 7.4 × 10²² kg

The distance between the earth and the moon, d = 3.84 × 10⁵ km = 3.84 × 10⁵ × 1000 m = 3.84 × 10⁸ m

G = 6.7 × 10^-11 N m² kg^-2

The force exerted by the earth on the moon is

F = G x (M m)/d²

F = 2.02 × 10²⁰ N

Thus, the force exerted by the earth on the moon is 2.02 × 10²⁰ N

For Half Wave rectifier:

• Average Vaule = Vm/r =π
• rms value = Vm /2
• Ripple factor = 1.21
• Form factor = 1.58
• Efficiency = 40.6 %

For Full Wave rectifier:

• Average Vaule = 2V m/π
• rms value = Vm /√2
• Ripple factor = 0.48
• Form factor = 1.11
• Peak factor = 1.41
• Efficiency= 81.2%

Among the given options, proofreading need the highest level of illumination. The illumination levels for different areas are given