{"id":87439,"date":"2025-06-01T06:44:14","date_gmt":"2025-06-01T06:44:14","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=87439"},"modified":"2025-06-01T06:44:14","modified_gmt":"2025-06-01T06:44:14","slug":"an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/","title":{"rendered":"An optical illusion which occurs mainly in deserts during hot summer i"},"content":{"rendered":"

An optical illusion which occurs mainly in deserts during hot summer is based on the principle of<\/p>\n

[amp_mcq option1=”Reflection” option2=”Interference” option3=”Dispersion” option4=”Total internal reflection” correct=”option4″]<\/p>\n

\n
\n
This question was previously asked in<\/div>\n
UPSC NDA-1 – 2017<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nOptical illusions like mirages, which occur in hot deserts or over hot surfaces, are caused by the refraction and subsequent total internal reflection of light as it passes through layers of air with different temperatures and densities. The air near the hot ground is less dense and has a lower refractive index than the cooler air above. As light rays from the sky or distant objects travel downwards into the hotter, less dense layers, they bend upwards away from the normal. If the angle of incidence becomes greater than the critical angle, total internal reflection occurs, causing the light rays to be reflected upwards towards the observer’s eyes. The brain perceives these rays as coming from below, creating the illusion of a reflection, often resembling a pool of water.
\n<\/section>\n
\n– Mirages are caused by the bending of light (refraction) due to varying refractive indices in air layers of different temperatures.
\n– Total internal reflection occurs when light travels from a denser medium to a less dense medium at a sufficiently large angle of incidence.
\n– In hot conditions, air near the surface is hotter and less dense, creating conditions for total internal reflection of light traveling from cooler, denser air above.
\n<\/section>\n
\nReflection is bouncing off a surface. Interference involves the superposition of waves. Dispersion is the splitting of light into its constituent colours based on wavelength. While refraction is the initial cause of bending, total internal reflection is crucial for the significant upward bending that creates the mirage image seen by the observer.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

An optical illusion which occurs mainly in deserts during hot summer is based on the principle of [amp_mcq option1=”Reflection” option2=”Interference” option3=”Dispersion” option4=”Total internal reflection” correct=”option4″] This question was previously asked in UPSC NDA-1 – 2017 Download PDFAttempt Online Optical illusions like mirages, which occur in hot deserts or over hot surfaces, are caused by the … <\/p>\n

Detailed SolutionAn optical illusion which occurs mainly in deserts during hot summer i<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1093],"tags":[1101,1153,1128],"class_list":["post-87439","post","type-post","status-publish","format-standard","hentry","category-upsc-nda-1","tag-1101","tag-optics","tag-physics","no-featured-image-padding"],"yoast_head":"\nAn optical illusion which occurs mainly in deserts during hot summer i<\/title>\n<meta name=\"description\" content=\"Optical illusions like mirages, which occur in hot deserts or over hot surfaces, are caused by the refraction and subsequent total internal reflection of light as it passes through layers of air with different temperatures and densities. The air near the hot ground is less dense and has a lower refractive index than the cooler air above. As light rays from the sky or distant objects travel downwards into the hotter, less dense layers, they bend upwards away from the normal. If the angle of incidence becomes greater than the critical angle, total internal reflection occurs, causing the light rays to be reflected upwards towards the observer's eyes. The brain perceives these rays as coming from below, creating the illusion of a reflection, often resembling a pool of water. - Mirages are caused by the bending of light (refraction) due to varying refractive indices in air layers of different temperatures. - Total internal reflection occurs when light travels from a denser medium to a less dense medium at a sufficiently large angle of incidence. - In hot conditions, air near the surface is hotter and less dense, creating conditions for total internal reflection of light traveling from cooler, denser air above.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"An optical illusion which occurs mainly in deserts during hot summer i\" \/>\n<meta property=\"og:description\" content=\"Optical illusions like mirages, which occur in hot deserts or over hot surfaces, are caused by the refraction and subsequent total internal reflection of light as it passes through layers of air with different temperatures and densities. The air near the hot ground is less dense and has a lower refractive index than the cooler air above. As light rays from the sky or distant objects travel downwards into the hotter, less dense layers, they bend upwards away from the normal. If the angle of incidence becomes greater than the critical angle, total internal reflection occurs, causing the light rays to be reflected upwards towards the observer's eyes. The brain perceives these rays as coming from below, creating the illusion of a reflection, often resembling a pool of water. - Mirages are caused by the bending of light (refraction) due to varying refractive indices in air layers of different temperatures. - Total internal reflection occurs when light travels from a denser medium to a less dense medium at a sufficiently large angle of incidence. - In hot conditions, air near the surface is hotter and less dense, creating conditions for total internal reflection of light traveling from cooler, denser air above.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T06:44:14+00:00\" \/>\n<meta name=\"author\" content=\"rawan239\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"rawan239\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"An optical illusion which occurs mainly in deserts during hot summer i","description":"Optical illusions like mirages, which occur in hot deserts or over hot surfaces, are caused by the refraction and subsequent total internal reflection of light as it passes through layers of air with different temperatures and densities. The air near the hot ground is less dense and has a lower refractive index than the cooler air above. As light rays from the sky or distant objects travel downwards into the hotter, less dense layers, they bend upwards away from the normal. If the angle of incidence becomes greater than the critical angle, total internal reflection occurs, causing the light rays to be reflected upwards towards the observer's eyes. The brain perceives these rays as coming from below, creating the illusion of a reflection, often resembling a pool of water. - Mirages are caused by the bending of light (refraction) due to varying refractive indices in air layers of different temperatures. - Total internal reflection occurs when light travels from a denser medium to a less dense medium at a sufficiently large angle of incidence. - In hot conditions, air near the surface is hotter and less dense, creating conditions for total internal reflection of light traveling from cooler, denser air above.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/","og_locale":"en_US","og_type":"article","og_title":"An optical illusion which occurs mainly in deserts during hot summer i","og_description":"Optical illusions like mirages, which occur in hot deserts or over hot surfaces, are caused by the refraction and subsequent total internal reflection of light as it passes through layers of air with different temperatures and densities. The air near the hot ground is less dense and has a lower refractive index than the cooler air above. As light rays from the sky or distant objects travel downwards into the hotter, less dense layers, they bend upwards away from the normal. If the angle of incidence becomes greater than the critical angle, total internal reflection occurs, causing the light rays to be reflected upwards towards the observer's eyes. The brain perceives these rays as coming from below, creating the illusion of a reflection, often resembling a pool of water. - Mirages are caused by the bending of light (refraction) due to varying refractive indices in air layers of different temperatures. - Total internal reflection occurs when light travels from a denser medium to a less dense medium at a sufficiently large angle of incidence. - In hot conditions, air near the surface is hotter and less dense, creating conditions for total internal reflection of light traveling from cooler, denser air above.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T06:44:14+00:00","author":"rawan239","twitter_card":"summary_large_image","twitter_misc":{"Written by":"rawan239","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/","url":"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/","name":"An optical illusion which occurs mainly in deserts during hot summer i","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T06:44:14+00:00","dateModified":"2025-06-01T06:44:14+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"Optical illusions like mirages, which occur in hot deserts or over hot surfaces, are caused by the refraction and subsequent total internal reflection of light as it passes through layers of air with different temperatures and densities. 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The brain perceives these rays as coming from below, creating the illusion of a reflection, often resembling a pool of water. - Mirages are caused by the bending of light (refraction) due to varying refractive indices in air layers of different temperatures. - Total internal reflection occurs when light travels from a denser medium to a less dense medium at a sufficiently large angle of incidence. - In hot conditions, air near the surface is hotter and less dense, creating conditions for total internal reflection of light traveling from cooler, denser air above.","breadcrumb":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/exam.pscnotes.com\/mcq\/an-optical-illusion-which-occurs-mainly-in-deserts-during-hot-summer-i\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/exam.pscnotes.com\/mcq\/"},{"@type":"ListItem","position":2,"name":"UPSC NDA-1","item":"https:\/\/exam.pscnotes.com\/mcq\/category\/upsc-nda-1\/"},{"@type":"ListItem","position":3,"name":"An optical illusion which occurs mainly in deserts during hot summer i"}]},{"@type":"WebSite","@id":"https:\/\/exam.pscnotes.com\/mcq\/#website","url":"https:\/\/exam.pscnotes.com\/mcq\/","name":"MCQ and Quiz for Exams","description":"","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/exam.pscnotes.com\/mcq\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209","name":"rawan239","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/761a7274f9cce048fa5b921221e7934820d74514df93ef195a9d22af0c1c9001?s=96&d=mm&r=g","caption":"rawan239"},"sameAs":["https:\/\/exam.pscnotes.com"],"url":"https:\/\/exam.pscnotes.com\/mcq\/author\/rawan239\/"}]}},"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/87439","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/comments?post=87439"}],"version-history":[{"count":0,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/posts\/87439\/revisions"}],"wp:attachment":[{"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/media?parent=87439"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/categories?post=87439"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/exam.pscnotes.com\/mcq\/wp-json\/wp\/v2\/tags?post=87439"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}