lenses.pptx quarter 2 topic in science 10

science 10 quarter 2

1. Uses and Functions of Different Optical Instruments

2. Optical instruments are based on optics. They usually used mirrors and lenses to either reflect or refract light rays to form object images or even enlarge images from far distances. Telescopes were the first optical instruments used for magnification of far objects and microscopes for magnifying small objects and images.

3. USES OF OPTICAL INSTRUMENTS WITH MIRRORS AND LENSES Shaving or Makeup Mirrors Concave mirrors commonly used as shaving mirrors and makeup mirrors. Vehicle Headlights Concave mirrors used usually in headlights of vehicles to reflect strong light rays. used to focus the light from the bulb. Light rays from the bulb are being reflected off by the concave mirror, creating a strong beam of light that shines on the road at night. Microscopes (mirror mounted at the base of the microscope). Concave mirrors are used in microscopes to collect light from a light source, shining it up onto a slide containing a specimen so it can be seen or viewed through the microscope’s magnification lens.

4. USES OF OPTICAL INSTRUMENTS WITH MIRRORS AND LENSES Telescopes- have a concave mirror at one end. the concave mirror in the telescope collects light. It directs the light rays from distant objects into a flat mirror. When a person looks through the lens on the eyepiece of the telescope and sees the image reflection on the mirror allowing a view of far objects that the naked eye is unable to see. Rear view mirror for Vehicle huge help for drivers to see back side of the vehicle while driving because it produces a wider scope for the driver to see it clearly. Eyeglasses- correct eye defects by diverging and converging out the light rays before it reaches the eye, thereby enabling the person using them to see distant and near objects more clearly.

5. USES OF OPTICAL INSTRUMENTS WITH MIRRORS AND LENSES Magnifying Glass A convex lens that is used to produce an enlarged image of an object. The lens is usually placed or mounted in a frame with a handle. A magnifying glass can be used to focus light, such as the sun's radiation at the focus to create a hot spot in a paper or wood for fire starting. Camera The aperture, which permits light to pass inside of the camera, corresponds to the pupil of the human eye. The lenses in a camera almost have the same function as the lens of the eye. Unlike the human eye, the lens system of the camera can be slid along its optical axis in order to focus on the film. The film also corresponds to the role of the retina. Additionally, cameras also have a shutter, which corresponds to the eyelids; it closes and opens quickly to shut the entry of light

6. EYE PROBLEMS: Myopia: (nearsightedness) This is a defect of vision in which far objects appear blurred but near objects are seen clearly. The object’s image is focused in front of the retina because the eyeball is too long or the refractive power of the eye’s lens is too strong. This defect can be corrected by wearing eyeglasses or contact lens with concave lenses that helps to focus the object’s image on the retina Hyperopia: (farsightedness) This is a defect of vision in which a person has difficulty seeing near objects but far objects can be seen easily. The object’s image is focused behind the retina rather than upon it. This occurs when the eyeball is too short. This defect can also be corrected by wearing eyeglasses or contact lens that contain convex lenses.

7. EYE PROBLEMS: Presbyopia: In an elderly person, accommodation power of their eye is decrease due to the decrease also of the elasticity of the lens of their eye. This lessens the ability of the eye muscle to adjust the size or roundness of lens of the eye and this condition is called presbyopia. This vision defect can be corrected using bifocal lenses . Astigmatism: This vision defect is the unevenness of the curvature of the lens of the eye that usually results in blurred vision accompanied with headaches sometimes. A person with astigmatism sees a vertical and horizontal lines distinct and unequal. This defect can be corrected with cylindrical lenses.

8. ½ LENGTHWISE (ANSWER ONLY) Fill in the blanks. Read the paragraph below and supply the blanks with correct answer. Refer to words in the box below for the possible answers. You can use each word once or twice. Concave mirrors are used usually in ____1____ of vehicles to reflect strong light rays. Instead of reflecting an image, it is used to focus the light from the bulb. Light rays from the bulb are being ____2_____ off by the ___3____ mirror, creating a strong beam of light that shines on the road at night. The concave mirror in the telescope ____4___ light. It directs the light rays from distant objects into a ___5___ mirror. A person looks through the lens on the eyepiece of the telescope and sees the image reflection on the mirror allowing a view of far objects that the naked eye is unable to see. _______1______is a defect of vision in which a person can see far objects appear blurred but near objects clearly. The object’s image is focused in front of the ____2_____because the eyeball is too ___3____ or the refractive power of the eye’s lens is too strong. This defect can be corrected by wearing ______4______with _____5____ lenses that helps to ____6____ the object’s image on the retina. ________7_____is a defect of vision in which a person has difficulty seeing near objects but far objects can be seen easily. The object’s image is focused ____8_____ the retina rather than upon it. This occurs when the eyeball is too ____9____. This defect can also be corrected by wearing glasses/contacts that contain ____10____ lenses.