Physics miscellaneous


  1. Amount of water vapour in the atmosphere is measured in terms of









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    Humidity is the amount of water vapor in the air. Water vapor is the gas phase of water and is invisible. Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin. This effect is calculated in a heat index table, used during summer weather. There are three main measurements of humidity: absolute, relative and specific.

    Correct Option: A

    Humidity is the amount of water vapor in the air. Water vapor is the gas phase of water and is invisible. Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin. This effect is calculated in a heat index table, used during summer weather. There are three main measurements of humidity: absolute, relative and specific.


  1. For a person having hypermetropia, the near point is










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    For a hyper-metropic eye ,the near points shift away from the eye i.e. farther away from the normal near point (25cm). In a hypermetropic eye, the light is not bent sufficiently so that it focuses at a point behind the retina. Here a person sees well for distance but near vision is difficult and causes strain. Hence hypermetropic people are called long-sighted. To correct the hypermetropic eye, a plus lens is required so that the light can now focus on the retina.

    Correct Option: A

    For a hyper-metropic eye ,the near points shift away from the eye i.e. farther away from the normal near point (25cm). In a hypermetropic eye, the light is not bent sufficiently so that it focuses at a point behind the retina. Here a person sees well for distance but near vision is difficult and causes strain. Hence hypermetropic people are called long-sighted. To correct the hypermetropic eye, a plus lens is required so that the light can now focus on the retina.



  1. In MRI machine, which one of the following is used?









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    Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to visualize internal structures of the body in detail. MRI makes use of the property of nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body. An MRI scanner is a device in which the patient lies within a large, powerful magnet where the magnetic field is used to align the magnetization of some atomic nuclei in the body, and radio frequency fields to systematically alter the alignment of this magnetization. This causes the nuclei to produce a rotating magnetic field detectable by the scanner—and this information is recorded to construct an image of the scanned area of the body.

    Correct Option: D

    Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to visualize internal structures of the body in detail. MRI makes use of the property of nuclear magnetic resonance (NMR) to image nuclei of atoms inside the body. An MRI scanner is a device in which the patient lies within a large, powerful magnet where the magnetic field is used to align the magnetization of some atomic nuclei in the body, and radio frequency fields to systematically alter the alignment of this magnetization. This causes the nuclei to produce a rotating magnetic field detectable by the scanner—and this information is recorded to construct an image of the scanned area of the body.


  1. Which one of the following determines the sharpness of image in a camera ?









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    Image quality is a characteristic of an image that measures the perceived image degradation (typically, compared to an ideal or perfect image). Imaging systems may introduce some amounts of distortion or artifacts in the signal, so the quality assessment is an important problem. Sharpness determines the amount of detail an image can convey. System sharpness is affected by the lens (design and manufacturing quality, focal length, aperture, and distance from the image center) and sensor (pixel count and anti-aliasing filter).

    Correct Option: A

    Image quality is a characteristic of an image that measures the perceived image degradation (typically, compared to an ideal or perfect image). Imaging systems may introduce some amounts of distortion or artifacts in the signal, so the quality assessment is an important problem. Sharpness determines the amount of detail an image can convey. System sharpness is affected by the lens (design and manufacturing quality, focal length, aperture, and distance from the image center) and sensor (pixel count and anti-aliasing filter).



  1. Lakes freeze in cold countries in winter, leaving the water underneath at









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    Lake ice cover is seasonal and occurs where average daily temperature is below the freezing point. Once formed the lake ice thickens over the course of the winter as the temperature gets colder. The lakes thermal structure prepares for ice with 0 (zero) degrees Celsius water at the surface and denser 4 degrees Celsius at the bottom. Once meteorological conditions provide colder air, relative to warmer water, the water does not get colder - instead ice forms.

    Correct Option: C

    Lake ice cover is seasonal and occurs where average daily temperature is below the freezing point. Once formed the lake ice thickens over the course of the winter as the temperature gets colder. The lakes thermal structure prepares for ice with 0 (zero) degrees Celsius water at the surface and denser 4 degrees Celsius at the bottom. Once meteorological conditions provide colder air, relative to warmer water, the water does not get colder - instead ice forms.