Science Q2 Test 3 & 4 PDF

Test IV: **Properties of EM Waves** 1. They are produced by accelerated or oscillating charge. 2. They do not require any material for propagation. 3. They travel in free space at the speed of 3x10\^8 m/s 4. Em waves carry radiant energy 5. Most EM waves are invisible to the eye but detec...

Test IV: **Properties of EM Waves** 1. They are produced by accelerated or oscillating charge. 2. They do not require any material for propagation. 3. They travel in free space at the speed of 3x10\^8 m/s 4. Em waves carry radiant energy 5. Most EM waves are invisible to the eye but detectable. Only the visible light is seen by humans. 6. The EM waves are often arranged in the order of wavelength and frequency in what is **known as electromagnetic spectrum** **Relationship of Frequency, Wavelength and Energy** Frequency (Hz)- number of waves move pass a point in one second. The more wiggles the higher the energy. - Directly proportional to energy - F increases/higher = E increases - F decreases/lower = E decreases Wavelength ( λ In meters) - length of a wave from crest. - Inversely proportional to frequency - Longer λ = lower f - Shorter λ = longer f Amplitude -- height of a wave Radio waves -- longest wavelength Gamma ray- highest frequency *Lowest to highest frequency:* **Radio Waves** **Microwaves** **Infrared Radiation (IR)** **Visible Light** **Ultraviolet (UV) Radiation** X**-rays** **Gamma Rays** Inverse Relationship - Frequency and wavelength - Wavelength and Energy Direct Relationship - Frequency and energy  **Orientation of Plane Mirror** Flat Mirrors (Plane) -- has a flat surface, does not distort the image. i.Follows Law of Reflection ii. **Characteristics:** - Virtual - left -- right reversed - Upright - same size PLANE MIRRORS - a mirror with a flat reflection - a polished or smooth surface (as of glass) that forms images by reflection, is a mirror with flat reflecting surface. - image is always the same distance behind the mirrors as the object is infront of the mirror. - image T the object always line up at the same normal. - image is upright (erect) but left-right reversed. **Angle of Incidence and Reflection** **Angle of Incidence (ϴi )** - angle between the reflected ray and the normal **Angle of Reflection (ϴr)** - angle between the reflected ray and the normal **The Law of Reflection states** : \" the angle of **incidence (incoming ray)** equals the angle of **reflection (outgoing ray)\"** **Multiple Images** **Types of Images:** a. **Real Image** - forms when light rays converge to form the image. - formed by the concave mirror or convex lens - When an object is farther from a concave mirror than twice the focal length, the image appears smaller and upside down. b. **Virtual Image** - reflections appear 3D even though it is not. - Light rays never meet *A virtual image* - formed by a plane mirror - always upright - appears to be as far behind the mirror as the object is in front of it. - **Types of Mirrors:** 1\. **Flat Mirrors (Plane)** -- has a flat surface, does not distort the image. i\. Follows Law of Reflection ii**. Characteristics**: virtual, upright, left -- right reversed, same size **Types of Reflection:** Reflection of light rays from **polished surface** \- When parallel light rays fall on a highly polished surface they are reflected as a parallel beam. \- **regular reflection.** Reflection of light rays from **rough surface** - light is reflected in many different directions. This is **diffuse reflection**. TEST III: ESSAY RADIATION lonizing Radiation - An especially damaging form of radiation is ionizing radiation, which can create electrically-charged ions in the material it strikes. This ionization process can break apart atoms and molecules, causing severe damage to living organisms, either by affecting living tissue directly or by prompting changes in the DNA. The most significant forms of ionizing radiation are: or directly cancer X-rays and gamma rays: High-energy parts of the electromagnetic spectrum Alpha particles: Atomic nuclei consisting of two protons and two neutrons Beta particles: Fast-moving electrons ejected from the nuclei of atoms Cosmic radiation: Energetic particles arriving at Earth from outer space Neutrons: Produced mainly in nuclear power plants Measuring Radiation The basic unit used to measure exposure to ionizing radiation is the sievert (Sv). It measures the biological effect of absorbed radiation, referred to as the effective dose or the weighted dose. Effects of Radiation on Living Organisms Living organisms are exposed to different Irrigation forms of radiation every day. Radiation only becomes a problem if we are exposed to too much MIOR of it. A familiar example is UV radiation from the sun here on Earth; overexposure to it may cause eye and skin damage, and in the worst case, lead to cataracts, glaucoma, or skin cancer. lonizing radiation can be very harmful, which is why it is useful in killing cancer cells as long as it is carefully directed so that its effect on healthy tissue is minimal. Large doses of ionizing radiation on the healthy tissue can result in cancer after a delay of a few years. At very high levels, high-energy weeks of exposure. By creating changes in the DNA, ionizing radiation can also cause genetic mutations that could affect future generations, but in fact, a person exposed to levels of radiation sufficiently high to cause mutations is more likely to die from the radiation exposure than pass the mutations to his/ her offspring. The level of damage caused by radiation depends on many factors such as the dose, the type of radiation, the part of the body exposed, and the age of the exposed living organisms. Embryos are particularly sensitive to radiation damage. Radiations affect humans in two ways: stochastic effects, which are associated with long-term, low-level exposure to radiation; and non-stochastic effects, which appear in cases of exposure to high levels of radiation and become more severe as the exposure increases. **Stochastic effects** are radiation effects in which the chance of occurrence increases with the dose. These effects can occur from the irradiation of only one cell; any exposure, however low, has some chance of causing the effect. Examples of stochastic effects include cancer and genetic mutations. **with long-term, low-level exposure to radiation** **non-stochastic effects** increase their severity as the dose increases. A threshold is generally. believed, hence if doses received are below the threshold dose, no effects will occur. These effects typically result trom the collective i injury of many cells, which include cataracts, skin burns, lowering of blood cell counts, etc. high level of **exposure (short term effect, high level of exposure)**