DRDO CEPTAM Tech-A flashcards
DRDO CEPTAM Tech-A · Build recall with a focused review session.
33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Successive percentage change
- Net change equals a + b + ab/100, where a and b are the two percentage changes with signs. A 20% rise followed by a 20% fall gives a 4% net decrease.
- Average speed, equal distances
- When a body covers two equal distances at speeds x and y, the average speed is 2xy/(x + y), which is the harmonic mean, not the arithmetic mean.
- Compound interest formula
- CI = P(1 + R/100)^T − P for annual compounding. For two years, the difference between CI and SI equals P(R/100)^2.
- Alligation rule
- The ratio in which two ingredients at prices c and d must be mixed to give mean price m is (d − m) : (m − c), where c < m < d.
- Clock hand angle
- The angle between the hour and minute hands at H hours and M minutes is |30H − 5.5M| degrees, taken as the smaller angle below 180 degrees.
- Syllogism validity test
- A conclusion follows only if it holds in every possible Venn diagram of the premises. A single counterexample arrangement makes it invalid.
- Odd days in calendar
- Odd days are the remainder when total days are divided by seven. A normal year has 1, a leap year 2, 100 years 5, and 400 years 0.
- Blood relation notation
- In a family tree, a plus sign marks a male and a minus sign a female. Vertical lines show parent-child links and horizontal lines show spouse or sibling.
- Universal blood donor
- O negative red cells are called the universal donor because they lack A, B and Rh D antigens. AB positive is the universal recipient of red cells.
- Electrical power formulas
- Power P equals VI, also I squared times R, also V squared divided by R. Energy billed in kWh equals watts times hours divided by one thousand.
- DRDO establishment
- The Defence Research and Development Organisation is India's defence research agency, formed in 1958 and headquartered in New Delhi.
- Affect versus effect
- Affect is usually a verb meaning to influence, while effect is usually a noun meaning a result. The medicine affected him; the effect was quick.
- Present perfect tense
- Formed with has or have plus the past participle. It links a past action to the present, as in 'She has finished the report'.
- Idiom: eleventh hour
- The phrase 'at the eleventh hour' means at the last possible moment, just before a deadline, not literally at eleven o'clock.
- Vernier calliper least count
- Least count equals one main scale division minus one vernier scale division. A 0.02 mm calliper has 50 vernier divisions spanning 49 main divisions.
- Micrometer least count
- Least count equals screw pitch divided by the number of circular scale divisions. A 0.5 mm pitch with 50 thimble divisions gives 0.01 mm.
- Transition fit
- A fit that may give either a small clearance or a small interference depending on the actual sizes of the hole and shaft within their tolerance zones.
- Tap drill size
- The tapping drill diameter is approximately the thread major diameter minus the pitch, giving about 75 percent thread engagement for metric coarse threads.
- Three-phase power
- For a balanced three-phase load, power equals root three times line voltage times line current times power factor, with voltage and current both line values.
- Star versus delta
- In star, line voltage is root three times phase voltage and line current equals phase current. In delta, line current is root three times phase current.
- Transformer EMF equation
- The induced EMF per winding is 4.44 times frequency times turns times peak flux. The voltage ratio equals the turns ratio for an ideal transformer.
- Motor synchronous speed
- Synchronous speed equals 120 times supply frequency divided by the number of poles. Slip is synchronous speed minus actual speed, divided by synchronous speed.
- DCEN versus DCEP
- In DCEN the electrode is negative and heat concentrates at the workpiece, giving deeper penetration. In DCEP heat concentrates at the electrode.
- Welding undercut defect
- Undercut is a groove melted into the base metal along the weld toe and left unfilled, typically caused by excessive current or too fast travel.
- Lathe cutting speed
- Cutting speed in metres per minute equals pi times diameter in millimetres times rpm divided by one thousand, where diameter is the workpiece diameter.
- Tailstock offset method
- Taper turning between centres by offsetting the tailstock suits long, shallow tapers. Offset equals total taper length times half the diameter difference, divided by taper length.
- Silicon diode drop
- A forward-biased silicon diode drops about 0.7 volts, while a germanium diode drops about 0.3 volts. Reverse bias blocks current except for leakage.
- Bridge rectifier frequency
- A full-wave bridge rectifier produces two output pulses per supply cycle, so the ripple frequency is twice the AC supply frequency.
- De Morgan's laws
- The complement of a product equals the sum of the complements, and the complement of a sum equals the product of the complements: (AB)' = A' + B'.
- Op-amp inverting gain
- For an ideal inverting amplifier the voltage gain is negative feedback resistance divided by input resistance. The non-inverting gain is one plus that ratio.
- Wheatstone bridge balance
- The bridge is balanced when the ratio of the two arms on one side equals the ratio on the other, giving zero current through the galvanometer.
- Transducer definition
- A transducer converts one form of energy into another, typically turning a physical quantity such as temperature or pressure into an electrical signal.
- Binary to decimal conversion
- Each binary digit is multiplied by the corresponding power of two and summed. Binary 1011 equals 8 + 0 + 2 + 1, which is decimal 11.