General Science & Physics

General Science & Physics

Supernova is:

A supernova marks catastrophic death of massive star exceeding Chandrasekhar limit, or white dwarf accreting matter triggering runaway thermonuclear fusion. Its luminosity briefly outshines entire galaxy, dispersing heavy elements synthesized via nucleosynthesis into interstellar medium.

Ref: Carroll and Ostlie, An Introduction to Modern Astrophysics, 2nd Edition, Chapter on Stellar Evolution and Supernovae, describes supernova as catastrophic explosion of massive star dispersing heavy elements and outshining galaxy, published by Cambridge University Press.

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General Science & Physics

What is the shape of a classical shaving mirror?

A shaving mirror uses concave spherical curvature with object inside focal length to produce erect enlarged virtual image. This magnification aids detailed grooming, unlike plane mirrors giving life-size view or convex mirrors diminishing image for wide field.

Ref: Hecht, Optics, 5th Edition, Chapter on Spherical Mirrors and Image Formation, explains concave mirrors produce magnified erect virtual image when object inside focal length used as shaving mirror, published by Pearson Education.

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General Science & Physics

One kilometre is equal to how many miles?

One mile equals 1.609344 km by international agreement, therefore conversion yields 1 km = 1/1.609 = 0.62137 miles approximating 0.62. This imperial-metric relationship is used universally in navigation, athletics and geographical distance calculations.

Ref: David A. Adler and John C. Hall, Physics for Scientists and Measurement Units, Chapter on Unit Conversion, discusses mile kilometre relationship with one mile equals 1.609 km and conversion to 0.62 miles per kilometre, published by Academic Press.

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General Science & Physics

Cynophobia is:

Cynophobia derives from Greek kyon meaning dog and phobos fear, classified as specific animal phobia in DSM-5. Excessive persistent fear of dogs causes avoidance behavior, sympathetic hyperarousal and panic, often originating from traumatic dog encounters during childhood.

Ref: American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders DSM-5, 5th Edition, Chapter on Specific Phobia, defines cynophobia as pathological fear of dogs from Greek kyon, classification and clinical features, published by APA.

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General Science & Physics

Golden revolution refers to:

Indian agricultural Golden Revolution 1991-2003 denotes rapid growth in horticulture produce including fruits, vegetables, flowers and honey. Led by Nirpakh Tutej, it transformed India into second largest horticulture producer, enhancing nutrition and farmer income diversification.

Ref: S.S. Acharya and M.P. Mohanty, Indian Agricultural Economy, Chapter on Agricultural Revolutions, describes Golden Revolution as period of horticulture growth including fruits and vegetables led by Nirpakh Tutej in India, published by Oxford University Press.

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General Science & Physics

When light passes from air to glass, its velocity:

Refractive index of glass (~1.5) exceeds air (~1.0). Since n=c/v and frequency remains constant, velocity v=c/n decreases upon entering denser medium. Wavelength shortens proportionally while frequency conserved, explaining refraction bending toward normal.

Ref: Hecht, Optics, 5th Edition, Chapter on Refraction and Snell's Law, explains refractive index relation n equals c over v, velocity decrease when light enters glass from air with constant frequency, published by Pearson Education.

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General Science & Physics

A railway carriage having a mass of 5000 kg is moving with a speed of 12 m/sec on a curve of 150 m radius. If the track

Lateral thrust equals centripetal force required for circular motion m v²/r. With m=5000 kg, v=12 m/s, r=150 m, force=5000×144/150=4800 N. Without superelevation, outer rail must provide this inward force, creating outward thrust.

Ref: R.S. Khurmi and J.K. Gupta, Theory of Machines and Engineering Mechanics, Chapter on Circular Motion, derives centripetal force formula m v squared by r and application to lateral thrust on railway outer rail, published by S. Chand.

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General Science & Physics

Hypermetropia is:

Hypermetropia occurs when eyeball is too short or lens power insufficient, focusing parallel rays behind retina. Distant objects appear clearer than near ones because accommodation cannot compensate, corrected by convex converging lenses, termed long sightedness.

Ref: Khurana, Comprehensive Ophthalmology, 7th Edition, Chapter on Errors of Refraction, defines hypermetropia as long sightedness with image focused behind retina due to short axial length corrected by convex lens, published by Jaypee.

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General Science & Physics

In a single throw of two dices, what is the probability of getting a sum of 8 or 11?

Total outcomes for two dice equal 36. Favorable combinations for 8 are (2,6)(3,5)(4,4)(5,3)(6,2) five cases, for 11 are (5,6)(6,5) two cases. Since mutually exclusive, probability equals 7/36 by addition rule.

Ref: Sheldon M. Ross, Introduction to Probability Models, 12th Edition, Chapter on Probability Axioms and Addition Rule, explains sample space of two dice as 36 outcomes and calculation of probability for sum 8 or 11, published by Academic Press Elsevier.

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General Science & Physics

The red soil is red in colour because it is:

Red soils obtain characteristic hue from ferric oxide coatings on soil particles, formed under well-drained, oxidizing tropical conditions with laterization. Weathering of iron-rich parent rocks releases iron that dehydrates to hematite, imparting red coloration, not humus content.

Ref: N.C. Brady and R.R. Weil, The Nature and Properties of Soils, 15th Edition, Chapter on Soil Genesis and Classification, explains red soils color due to ferric oxide and hematite coatings from iron-rich parent material, published by Pearson.

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General Science & Physics

Which of the following element is used as the photoconductive material used in the drum of photocopier machine?

Selenium exhibits photoconductivity, becoming conductive when illuminated and insulating in darkness. In xerography, a selenium-coated drum holds electrostatic charge selectively discharged by light reflected from document, allowing toner adhesion to form printed image.

Ref: Sze and Lee, Semiconductor Devices Physics and Technology, 3rd Edition, Chapter on Photoconductivity and Photovoltaic Devices, explains selenium as photoconductive material used in xerographic drum of photocopier machines, published by Wiley.

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General Science & Physics

Cervical cancer is strongly associated with:

Persistent infection with high-risk Human Papillomavirus types 16 and 18 integrates E6/E7 oncoproteins that degrade p53 and Rb, driving cervical dysplasia. Over 95% of cervical cancers show HPV DNA, establishing viral etiology and vaccines as preventive strategy.

Ref: Kumar, Abbas and Aster, Robbins and Cotran Pathologic Basis of Disease, 10th Edition, Chapter on Female Genital Tract, discusses cervical cancer pathogenesis strongly linked to high-risk HPV infection with E6 E7 oncoproteins, published by Elsevier.

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