BSF Tradesman cheat sheet

Indian Constitution came into force on 26 January 1950; Dr B. R. Ambedkar chaired the Drafting Committee; the Preamble was amended once, by the 42nd Amendment (1976), which added socialist, secular and integrity.

Fundamental Rights sit in Part III (Articles 12-35); Directive Principles in Part IV (Articles 36-51); Fundamental Duties in Part IVA (Article 51A, added by the 42nd Amendment on the Swaran Singh Committee's recommendation).

RBI was nationalised in 1949 and is India's central bank; it issues currency, sets the repo rate through the Monetary Policy Committee, and regulates banks. SBI was formed in 1955 from the Imperial Bank.

ISRO milestones: Aryabhata (1975, first satellite), Chandrayaan-1 (2008), Mangalyaan (2013), Chandrayaan-3 soft landing near the lunar south pole (August 2023).

National symbols: tiger is the national animal, peacock the national bird, Ganga the national river, and 'Jana Gana Mana' (Rabindranath Tagore) the national anthem.

Static geography anchors: Tropic of Cancer passes through 8 states; the Deccan Plateau lies between the Western and Eastern Ghats; the Sundarbans is the world's largest mangrove forest.

Current-affairs window rule: questions normally refer to the 6-12 months before the exam date, so track appointments, awards, defence exercises and sports championships from the past year.

Number-series rule: check differences, then ratios, then squares/cubes, then alternating or two interleaved series before assuming a single pattern.

Alphabet positions: A=1 ... Z=26. Opposite-letter pairs sum to 27 (A-Z, B-Y, C-X), which solves most letter-coding questions quickly.

Coding-decoding: identify whether the shift is constant (+1, +2), positional, reversed, or based on the opposite letter; test the rule on two letters before applying it.

Blood relations: draw a family tree with gender marks; vertical lines mean generations, horizontal lines mean siblings or spouses, and 'only son of my grandfather' type phrases fix the speaker.

Direction sense: use a compass sketch; on a right turn from North you face East, a left turn from East faces North, and final displacement is the straight-line distance, not the sum of steps.

Odd-one-out and analogy: look for shared class (all but one are metals, all but one are prime), or a fixed relation such as tool-to-user, cause-to-effect, or part-to-whole.

Syllogism: a conclusion follows only if it is true in every possible Venn diagram of the premises; 'some' statements cannot yield 'all' conclusions, and two particulars give no conclusion.

Ranking and seating: for a row of n people, position from left + position from right = n + 1; in circular seating, facing centre means left is clockwise.

Percentage change = (change/original) x 100; successive changes of a% and b% give a net change of a + b + ab/100 percent.

Profit and loss: profit% is always on cost price; SP = CP x (100 + profit%)/100, and discount% is always on marked price.

Simple interest = P x R x T/100; compound interest = P(1 + R/100)^T - P; for two years CI - SI = P(R/100)^2.

Time and work: if A alone takes a days and B alone b days, together they take ab/(a + b) days; use LCM of days as total units of work.

Speed: distance = speed x time; 1 km/h = 5/18 m/s; for equal distances at speeds x and y, average speed = 2xy/(x + y).

Ratio and mixture: in an alloy of A:B = m:n, quantity of A = total x m/(m + n); alligation gives the mixing ratio as (mean - cheaper):(dearer - mean).

Mensuration: area of circle = pi r^2, circumference = 2 pi r; volume of cylinder = pi r^2 h; volume of cone = (1/3) pi r^2 h; total surface of cube = 6a^2.

Average = sum of observations/number of observations; if every value rises by k, the average rises by k, and the new average of n values after adding x is (old sum + x)/(n + 1).

Hindi noun gender rule: words ending in 'aa' (e.g., ladkaa, ghar) are usually masculine; those ending in 'ii' (ladkii, nadi) are usually feminine, with exceptions like 'paani' (masculine).

Hindi case markers (kaarak chinh): ne (agent), ko (object), se (instrument/ablative), ka/ke/kii (genitive), and mein (locative); the postposition changes form with the noun's number and gender.

Common Hindi spelling traps: 'kriya' not 'kiriya', 'vidyaarthi' with 'r' after 'd', and distinguish 'sh' (श) from 'shh' (ष) and 'n' (न) from 'nn' (ण).

English subject-verb agreement: singular subject takes a singular verb; with 'either...or' and 'neither...nor' the verb agrees with the nearer subject.

English articles: 'a' before consonant sounds, 'an' before vowel sounds (an hour, a university), and 'the' for something already specified or unique.

Direct to indirect speech: change the reporting verb tense back one step, change pronouns to the third person, and shift time words (today to that day, tomorrow to the next day).

Idioms appear literally wrong but fixed: 'to let the cat out of the bag' means to reveal a secret, and 'a bolt from the blue' means a sudden shock.

Active to passive: object becomes subject, verb becomes be + past participle, and the agent follows 'by'; keep the original tense.

Ohm's law: V = IR; power P = VI = I^2 R = V^2/R. In a series circuit current is common, in a parallel circuit voltage is common.

Domestic supply in India is 230 V single phase, 50 Hz; three-phase supply is 415 V with a phase difference of 120 degrees between phases.

Fitter: a micrometer least count is pitch/number of divisions on the thimble (commonly 0.01 mm); a vernier caliper typically reads to 0.02 mm.

Welding: in arc welding the electrode is the filler and one terminal; a 6013 electrode means 60,000 psi tensile strength and all-position use; AC or DC polarity (straight or reverse) changes penetration.

Carpentry: season timber to reduce moisture before use; common joints are mortise and tenon, dovetail, half-lap and butt; a try square checks squareness at 90 degrees.

Masonry: cement:sand 1:6 is used for brickwork mortar, 1:3 for plaster; bricks are soaked before laying to stop them absorbing water from the mortar.

Painting: a primer seals the surface and improves adhesion; putty fills dents; the finish coat is applied after the primer dries, and each coat dries before the next.

Mechanic: a four-stroke engine cycle is intake, compression, power and exhaust, taking two crankshaft revolutions; valve clearance is set when the engine is cold.

Fire classes: A for solid combustibles (water), B for flammable liquids (foam, CO2), C for gases, D for metals, and electrical fires need CO2 or dry powder, never water.

Lockout/tagout: switch off, isolate, tag and lock the supply, then verify dead with a tester before touching a circuit.

Personal protective equipment: safety goggles for grinding and chipping, leather gloves for welding and hot work, helmet and safety shoes on site, and ear protection above noisy machines.

Electrical first aid: switch off the supply or use a dry wooden pole to separate the victim, then start CPR if breathing has stopped; never touch a victim still in contact with live parts.

Hand tools: a spanner must fit the nut exactly (no pipe extensions), files cut on the forward stroke only, and a hacksaw blade is fitted with teeth pointing forward.

Bench work: hold work in a vice at elbow height, keep files and chisels sharp, and never blow metal chips with the mouth; use a brush or compressed air with eye protection.

Lifting and housekeeping: bend the knees, keep the load close, and never lift beyond capacity; clear walkways and stack material so it cannot topple.

Welding safety: screen the arc from others, keep cylinders upright and secured, and never use oil on oxygen fittings; acetylene is never used above about 1 bar.

Units: 1 byte = 8 bits; 1 KB = 1024 bytes, 1 MB = 1024 KB, 1 GB = 1024 MB; hardware is physical, software is programs.

RAM is volatile working memory cleared on shutdown; ROM is non-volatile and holds firmware such as the BIOS.

Common shortcuts: Ctrl+C copy, Ctrl+V paste, Ctrl+X cut, Ctrl+Z undo, Ctrl+S save, Ctrl+P print, Alt+Tab switch windows.

File extensions: .docx Word, .xlsx Excel, .pptx PowerPoint, .pdf portable document, .jpg image, .mp3 audio, .exe executable.

Internet basics: IP address identifies a device, DNS converts names to IP addresses, HTTP/HTTPS transfers web pages, and HTTPS encrypts traffic.

Email: To, Cc (visible copy), Bcc (hidden copy), Subject and Body; never open attachments from unknown senders, and use strong unique passwords.

Digital payments: UPI transfers money using a virtual payment address; OTP is a one-time password and must never be shared, and a phishing link mimics a genuine site to steal credentials.

Government digital services: DigiLocker stores verified documents, Aadhaar enables e-KYC, and UMANG gives access to central and state services on one app.