THDC JE flashcards

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

Characteristic strength of concrete

The compressive strength below which not more than 5 percent of test results fall, measured on 150 mm cubes at 28 days; denoted fck, as in M20 concrete.

Slump test purpose

A workability test for fresh concrete in which a moulded cone is allowed to subside; the measured drop indicates consistency and suitability for placing without segregation.

Transformer EMF equation

RMS induced EMF equals 4.44 times frequency times maximum flux times number of turns. It explains why a transformer designed for one frequency cannot be operated at another.

Synchronous speed formula

Ns equals 120 times supply frequency divided by the number of poles, in rpm. Slip is the difference between synchronous and rotor speed divided by synchronous speed.

Carnot efficiency

The maximum possible efficiency of a heat engine operating between a hot reservoir at T1 and a cold reservoir at T2, equal to 1 minus T2/T1 using absolute temperatures.

Ideal op-amp assumptions

Infinite open-loop gain, infinite input impedance, zero output impedance and infinite bandwidth. These justify the virtual short and zero input current used in circuit analysis.

Simply supported beam moment

For a beam of span L carrying a central point load W, the maximum bending moment is WL/4 at midspan and the maximum shear force is W/2 at the supports.

Three-phase power formula

Active power equals square root of three times line voltage times line current times power factor. Power factor is the cosine of the angle between voltage and current.

Compound interest formula

Amount equals principal times one plus rate over 100, raised to the number of years. Compound interest is the amount minus the principal.

Successive percentage change

Two successive changes of a percent and b percent produce a net change of a plus b plus ab over 100 percent. Signs are taken as positive for increase, negative for decrease.

Train crossing a platform

The time taken equals the sum of train length and platform length divided by speed. A pole or signal post has zero length, so only the train length matters.

Combined average of groups

When groups of sizes n1 and n2 have averages A1 and A2, the combined average is the sum of n1A1 and n2A2 divided by n1 plus n2.

Work done together

If one person finishes a job in x days and another in y days, working together they finish it in xy divided by x plus y days.

Alligation rule

The ratio in which two ingredients of known prices must be mixed to obtain a mean price is the difference between mean and cheaper, to the difference between dearer and mean.

nCr formula

The number of ways to choose r items from n without regard to order equals n factorial divided by r factorial times n minus r factorial.

Opposite letters in alphabet

Letters equidistant from the two ends of the alphabet sum to 27: A pairs with Z, B with Y, C with X. Useful for coding-decoding and letter analogy questions.

Syllogism validity rule

A conclusion follows only if it is true in every possible Venn diagram consistent with the premises. A statement true in one arrangement alone is not a valid conclusion.

Circular seating direction

For people facing the centre, the immediate left of a person is clockwise around the circle. When facing outward, left and right are reversed.

Blood relation: maternal uncle

The maternal uncle is the mother's brother. The paternal aunt is the father's sister. Mapping the family tree with gender markers prevents common confusion.

Number series second difference

If first differences are not constant, compute second differences; a constant second difference indicates a quadratic pattern of the form an squared plus bn plus c.

Directive Principles location

Directive Principles of State Policy appear in Part IV, Articles 36 to 51, of the Indian Constitution. They are not enforceable in courts but guide state policy.

THDC India Limited

A joint venture of the Government of India and the Government of Uttar Pradesh, incorporated in 1988 and headquartered at Rishikesh, Uttarakhand, operating the Tehri complex.

Repo rate meaning

The rate at which the Reserve Bank of India lends short-term funds to commercial banks against securities. Raising it is a contractionary monetary measure to curb inflation.

Fundamental Rights part

Fundamental Rights are contained in Part III of the Indian Constitution, Articles 12 to 35, and are enforceable through writs under Article 32.

India net-zero target

India announced at COP26 in Glasgow a target of net-zero emissions by 2070, along with a goal of 500 gigawatts of non-fossil electricity capacity by 2030.

Chandrayaan-3 landing

India's Chandrayaan-3 mission achieved a soft landing near the lunar south pole in August 2023, making India the first country to land in that region.

G20 summit 2023

India hosted the G20 Leaders' Summit in New Delhi in 2023, where the African Union was admitted as a permanent member of the grouping.

Tehri Dam river

The Tehri Dam is built on the Bhagirathi river in Uttarakhand. The complex also includes the Koteshwar Dam downstream and a pumped storage plant.

Past perfect tense use

Formed with had plus past participle, it marks the earlier of two past actions, as in 'The train had left before we reached the station'.

Active to passive conversion

The object becomes the subject, the verb becomes a form of be plus past participle, and the original subject follows 'by', if retained.

Affect versus effect

Affect is usually a verb meaning to influence. Effect is usually a noun meaning a result. 'The rain affected the match; the effect was a draw.'

OSI transport layer

The fourth layer of the OSI model, responsible for end-to-end delivery, segmentation and reliability. TCP and UDP operate at this layer, above the network layer.

Absolute cell reference

In a spreadsheet, a reference written with dollar signs, such as $A$1, that does not change when the formula is copied to other cells.

Ransomware definition

Malicious software that encrypts a victim's files or locks the system and demands payment for restoration. Regular offline backups are the main defence.