RRB JE CBT 2 Civil flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Target mean strength formula

For concrete mix design, target mean strength is characteristic strength plus 1.65 times the assumed standard deviation, giving the margin needed so no more than 5 percent of results fall below the characteristic value.

Development length of bar

The embedded length needed to transfer bar force to concrete without slipping, computed as bar diameter times stress divided by four times the design bond stress; deformed bars get a 60 percent increase.

Effective span of beam

The lesser of clear span plus effective depth, or clear span plus half the sum of the two support widths; it is the span used for bending moment and deflection calculations.

Rise and fall in levelling

Rise equals backsight minus foresight; a positive value means the new station is higher, a negative value means it is lower, and the reduced level is adjusted accordingly.

First railway line in India

Opened in 1853 between Bombay (Bori Bunder) and Thane, covering about 34 kilometres; it marked the beginning of railway development in the country.

Article 32 of the Constitution

Gives citizens the right to move the Supreme Court for enforcement of fundamental rights through writs; Dr Ambedkar called it the heart and soul of the Constitution.

Repo rate meaning

The rate at which the Reserve Bank of India lends short-term funds to commercial banks against government securities; raising it tightens liquidity and is used to control inflation.

Chittaranjan Locomotive Works

A railway production unit in West Bengal that manufactures electric locomotives for Indian Railways; it is one of the major production units of the national rail network.

Newton's second law

The net force on a body equals the rate of change of its momentum; for constant mass this becomes force equals mass times acceleration, measured in newtons.

Young's modulus definition

The ratio of tensile or compressive stress to the corresponding strain within the elastic limit; it measures stiffness, so a higher value means the material stretches less under the same stress.

Power of a lens

The reciprocal of focal length expressed in metres, measured in dioptres; a convex lens has positive power, a concave lens has negative power, and a shorter focus means higher power.

Carnot efficiency

The maximum possible efficiency of a heat engine operating between a hot source and a cold sink, equal to one minus the ratio of sink to source temperature, both in kelvin.

pH scale meaning

A measure of hydrogen ion concentration equal to the negative logarithm of hydrogen ion concentration; values below 7 are acidic, 7 is neutral and above 7 is basic.

OIL RIG mnemonic

Oxidation is loss of electrons and reduction is gain of electrons; the mnemonic helps assign oxidation states and balance redox equations in electrochemistry questions.

Universal logic gates

NAND and NOR gates are called universal because any other logic gate, including AND, OR and NOT, can be constructed using only NAND gates or only NOR gates.

Absolute cell reference

In spreadsheets, a reference written with dollar signs such as $A$1 that stays fixed when the formula is copied to other cells, unlike a relative reference.

IPv4 versus IPv6

IPv4 addresses are 32 bits long and written as four decimal octets; IPv6 addresses are 128 bits long, written in hexadecimal groups, and were created to overcome address exhaustion.

Operating system function

System software that manages hardware resources, schedules processes, handles memory and files, and provides services so application software such as word processors can run.

Computer generations

Successive hardware eras: vacuum tubes first, transistors second, integrated circuits third, microprocessors fourth, and artificial-intelligence-based systems fifth, each bringing smaller and faster machines.

PM2.5 and PM10

Airborne particulate matter classified by aerodynamic diameter in micrometres; PM2.5 is finer, travels deeper into the lungs and is more damaging to health than PM10.

BOD versus COD

Biochemical oxygen demand measures oxygen used by microbes to break down organic matter, usually over five days; chemical oxygen demand measures chemical oxidation and is always the larger value.

Eutrophication definition

Nutrient enrichment of a water body, typically by nitrates and phosphates, causing excessive algal growth, oxygen depletion and harm to fish and other aquatic organisms.

Electrostatic precipitator

An air pollution control device that charges dust particles and collects them on oppositely charged plates; it removes fine particulates from flue gas with high efficiency.

Ambient noise unit

Environmental noise is measured in decibels on the A-weighted scale, written dB(A), which approximates how the human ear responds to sound of different frequencies.

Catalytic converter role

A device in vehicle exhaust that uses a catalyst to convert carbon monoxide, unburnt hydrocarbons and nitrogen oxides into less harmful carbon dioxide, water vapour and nitrogen.

3-4-5 right angle rule

A triangle with sides in the ratio 3:4:5 has a right angle between the shorter two sides; surveyors use it to set out perpendicular offsets from a chain line.

Unit weight of steel bar

A steel bar of diameter d millimetres weighs approximately d squared divided by 162 kilograms per metre; a 12 millimetre bar therefore weighs about 0.89 kilograms per metre.

Dry volume factor

Wet volume of concrete or mortar is multiplied by about 1.30 to 1.54 to obtain dry volume, because bulking of sand and voids increase the loose volume of dry ingredients.

First-angle projection layout

A drawing convention in which the object is imagined between observer and plane, so the top view is placed below the front view and the left side view appears on the right.

Gradient as a ratio

Vertical rise divided by horizontal distance, written as 1 in n or as a percentage; a 1 in 40 gradient over 20 metres gives a rise of 0.5 metres.

Work-sharing time formula

If two workers alone complete a job in x and y days, working together they finish it in xy divided by x plus y days, assuming their rates simply add.

Trapezoidal trench volume

Volume equals average of top and bottom widths, multiplied by depth and length; used to estimate earthwork for trenches and canals with sloping sides.