Category: Physics

  • HOTNESS: HOW TO EXPLAIN HOT AND COLD

    HOTNESS: HOW TO EXPLAIN HOT AND COLD

    HOTNESS-SCIENCE BLOG

    INTRODUCTION

    We term heat as energy of hotness, it makes  the object hot . We feel cold in winter, specially inside the room. But when we go outside in front of sunrays, then we feel  warm.   We term the temperature as the measurement of degree of hotness  or coldness.  This property indicates whether the substance is hot or cold. A high temperature informs us that the object is very hot. Beside it ice has very low temperature as  it is called very cold.

    We measure the temperature by a device which we term as thermometer.  This has marking of scale on it which we read as temperature.  Each division of scale is degree of hotness.  The thermometers are mercury  thermometer. In some thermometer the scale marking is from 0° to 100°. This scale we term as  Celsius  scale. We use this Celsius scale in measuring  weather temperature or measuring  temperature in laboratory. Another measuring scale of  hotness is Farenhit.  It has marking from 32° to 212° .  Total 180 scales are there. So, when  we supply a particular amount of heat  to the thermometer bulb  consisting  mercury, then the mercury expands due to hotness and gets rises in the glass tube of thermometer. In this way we can use this fact to measure the temperature.

    READING OF CLINICAL THERMOMETER IN HOTNESS

    Step 1 Firstly,  we must wash the thermometer with an antiseptic  solution and if in case, the antiseptic solution is not available, we should wash it with water.

    Step 2 We must hold the thermometer with care in hand. We should jerk the mercury of thermometer in such a way that mercury in  the thermometer tube goes down under  95°F or  35°C.

    Step 3 Now, we should put the thermometer bulb under the tongue of the patient for about one minute. Then we take out the thermometer from patient’s mouth.

    Step 4 In order to read the temperature, we should hold the thermometer horizontally in our hand and rotate it slowly.  If we observe the bigger image of mercury inside the thermometer tube, then we can understand a position of the tube. Now,  it is the time to read the temperature reading due to hotness on the  glass along with the top portion of mercury thread.

     ANSWER THE FOLLOWING  IN BRIEF :

    Qs1:  If we construct a house in a coastal area, we should place the windows in which direction? why?

    Ans1: Windows should preferably towards the sea beach so that the sea breeze coming from the sea keeps the house cool during the day time.

    Qs2: The mercury  level does not change even if the clinical thermometer is taken out from the mouth of the patient. Explain the statement on hotness, why?

    Ans2: Because of the  kink present in the thermometer, the mercury does not fall or rise.

    Qs3:  Suppose  we heated a pan on fire, if we remove it , the pan becomes cooled. Why is it happened?

    Ans3:  If we remove a pan from the source of heat, then it releases heat by radiation process around itself and becomes cool.

     Qs4:  In which process of heat requires no medium.

     Ans4:  In the radiation process medium is not required.

    CONCEPTUAL  QUESTIONS ON HOTNESS:

    Qs5:  If we observe a thermometer containing mercury inside, we see the mercury level increases in contact of hot object. Why is it happened?

     Ans5:  In contact of hot object,  mercury  expands as it is metal.  That is why  levelof mercury increases.

    Qs6: The radiators in cars are painted black. Explain why?

    Ans6: Since, the black bodies are better radiators as black absorbs heat properly , so due to this reason, we use to paint the car radiators black.

    Qs7: Why should we like to take two thin blankets than one thick blanket in winter.

     Ans7:   There is an air gap in between two thin blankets . This phenomenon  does not allow heat pass out from the body and it is not as such as in case of one thick blanket.

    Qs8:  We should not hold the thermometer bulb while observing temperature, why?

     Ans8: We should not hold the bulb of thermometer when we want to read the level of mercury. Because  the level of mercury increases due to hotness while touching from the actual reading by our body temperature.

    Qs9:  Imagine there are two different colored tent in a tourist place. One tent is made up of black color material, another with white color cloth.  In a hot summer afternoon in which tent will you want to rest? Which tent will you prefer in winter? Give reason.

    Ans9: We will  like to stay in white fabric tent in case of summer because it reflects all the radiations from the sun and keeps us cool inside the tent.

    But in case of winter, we should not use white fabric tent, we should use black fabric tent as it absorbs all colors of light from the sun and keeps us warm inside the tent.

    EXPLAIN THE QUESTION ANSWER IN HOTNESS

    Qs10: Study  the following statement “  when we apply  heat at the bottom of the water vessel, then the bottom part becomes heated fast than that of top”: justify your statement .

     Ans10:  The particles of water at the bottom become hot and lighter. So it comes up in the middle.  For this reason, upper portion cold water particles which are heavy also settle down at the bottom. In this way heat flows in convection mode and make the water hot.  If we apply heat at the top, then  hot and lighter water particles are not moving. Only upper surface of water is heated.  As we know that  water cannot conduct heat properly. So, bottom part of water remains cold.

     Qs11:  Why do we serve hot tea or coffee or soup in china clay cup or bowl?

    Ans11: Generally we serve hot tea or coffee in china clay cup or pot. Because china clay material  is a poor conductor of heat. This material does not allow heat to be released outward, and keeps the tea hot for long time.

    Qs12:  What is the reason  that we cannot measure clinical thermometer  of hotness in case of high temperature?

     Ans12:  There is a limited range of temperature in Clinical thermometer, i.e. 35°C to  42°C OR  95°F to 105°F. Mercury is dangerous for living organism. So, by using mercury thermometer for measuring high temperature may cause an accident by breaking. That is why we must avoid mercury temperature to get high temperature.

  • LENS FORMULA: HOW TO DRAW A REFLECTION DIAGRAM

    LENS FORMULA: HOW TO DRAW A REFLECTION DIAGRAM

    LENS FORMULA

    INTRODUCTION

    It is a transparent refracting medium bounded by  two or at least one spherically curved surface in lens formula. 

    What is lens using in various device :In a microscope or in a telescope convex lenses are used to see distant or much closer objects.

    What is the type: Convex and Concave lens.

    What is the definition:

    Convex lens:  This type is thicker in the middle and thinner at the edges; in other words, it is a piece of a transparent medium that bulges out in the middle.

    Concave lensThe shape of this type is just opposite to that of a convex type. It is thinner in the middle and thicker at the edges; in other words, it is a piece of a transparent medium bent inwards in the middle.

    What is the structure  formed:  A convex type or concave type is the combination of frustum of prisms. We know that when a light ray falls on a prism it always bends towards the base of prism. The base of these prisms in a convex lens is towards principal axis of this type. Similarly in a concave lens base of the frustum of prism is away from the principal axis .

    What is the activity on light on convex type:  If any parallel light ray falls on the convex type, when it strikes on any frustum of the prism it bends towards the base of this prism .Consequently all parallel light ray falling on one or the other such prisms bend towards their bases.  Since all bases are facing towards the principal axis the rays also converge towards the principal axis at a point which is known as real focus . 

    What is the another name : For this property this type is also known as a converging lens. 

    What is the activity on light on concave type:  If any parallel light ray falls on this  structure, when it strikes on any frustum of the prism it bends towards the base of this prism. Consequently all parallel light rays falling on one or the other such prisms bend towards their bases. Since all bases are facing away from the principal axis the rays appear to be coming from the point which is known as virtual focus . 

    What is another name: For this reason this type is also known as a diverging lens.

    What is the application :i) Eye lens is a convex type that forms the real and inverted image of any object on the retina.

    ii) The eyepiece used in a camera, microscope and telescope are convex  

    iii) A magnifying glass is a convex  used to  watch minute objects. 

    iv) Spectacles are convex or concave to correct the vision of our eyes.

    v) A concave  is used in a Gallilean telescope.

    What is power: Power of a lens is defined in terms of the deviation produced by the this structure. 

    We know, that a lens of smaller focal length deviates the light rays more than that  of higher focal length. More is  deviation of light higher is the power . Numerically the power  is equal to reciprocal of focal length  in meter. Power (P) = 1/ focal length in meter 

    The unit of power is dioptre (D) .Convex type has positive (+) power and concave type has negative (-) power. When two or more thin structures are put in contact the power of the combination is equal to algebraic sum of powers of the lenses. If P1, P2, P3………..are the powers of the thin structureis equal to  the power of combination of lenses ,P = P1 + P2 + P3 +……… 

    What is a macro lens : It  is a dedicated camera  lens that is optically optimized to handle extremely  close focusing distances and can take sharp, highly  detailed images of microscopic subjects. Macro lens is mainly used in photography. (what is a macro lens)

    what is a macro type best example: 

    •  1 -Canon EF 100mm f/2 .8L Macro IS STM
    •  2 -Canon EF-S 35mm f/2.8 Macro IS STM
    •  3 -Tamron  SP 90mm f/2.8 Di VC USD Macro.
    •  4-Nikon AF-s 105mm f/2.8 G IF ED VR Micro.

    What is a macro  focal length :There are many different  macro types on the market today, with focal lengths from 15mm to 200mm. most of the macro hit the same 1:1 magnification ratio that gives shooters the life sized reproduction they want for superb close-ups.

    What is a macro type detection: If this structure  with a magnification ratio of 1:1 or 2:1 or 3:1 then it is a macro .  If the magnification ratio is 1:2, 1:3, 1:4 etc then it is not macro. 

    What is a macro lens advantage:  This macro lens is good for shooting. Macro lens is used for close up. Macro lens is also used in close up photography.  A macro lens is a special type of camera lens that has the ability to work with very short focusing distance.  Macro lens is useful in taking sharp image of very small object.  What is a Macro type focusing distance : It is around 30 cm. 

    What is the disadvantage: Sometimes macro lens can degrade the quality of the image. 

    What is a macro \type termed so :Actually macro lens provides a large view of a small object. In other words,  macro lens makes the micro image MACRO.

    What are toric lenses :A toric type  is a type  having different optical power and focal length in two orientations perpendicular to each other. One of the surfaces is shaped like a cap from a torus and  other one is usually spherical. Such toric type behaves like a combination of spherical and  cylindrical lens 

    What are Toric lenses functions :A toric type is a contact lens that is shaped in a particular way.  The shape of toric type creates different refractive , or focusing, powers on the vertical and horizontal orientations.  If the object is moved around the toric type the refractive strength increases or decreases gradually.

    What are  constituent of toric:  The toric  is made of some bio-compatible lens material. Toric IOL   technology uses bio-compatible material  have been successfully used in contact lens.

    What are toric  problem of  becomeing blurry:  Toric is used in making contact lens.  If it is used for long time   then eyes may become blurred because of much dryness of inside our eye and the weighed lens  can’t swivel to be the right way up again by each blinking 

    What are toric  comfortibility: Toric  is of  different types   with soft lenses which are the most popular among every one.  Users feel most comfortable using these toric  because of the hydrogel component,  which provides safety and  comfort. 

     What are  uses of toric: Toric type with different optical power and focal length are primarily used in  eye glasses , contact lense and intraocular lenses to correct astigmatism. 

    Toric IOL reduce lifetime economic costs by reducing the need for glasses or contact lenses following cataract removal.   This results can inform  physicians and patients regarding the value of toric IOL in the treatment of  cataract  and pre-existing astigmatism