The crust

Classification of volcanoes

Effects of Volcanoes

1. Landscape: Most of the earth’s surface is covered with volcanic rocks.Volcanoes are also responsible for the formation of many mountains and islands.
2. Vegetation and wildlife: Volcanic eruption sometimes set the surrounding vegetation into fire.Wild animals are also killed by being buried into the lava or being burnt by the forest fires.
3. Environment: Volcanic eruptions emit harmful gases into the environment. Such gases include sulphur dioxide. Some of the gases contribute to global warming and climate change.
4. Human life and property: Volcanic eruptions sometimes kill people and destroy property.
5. Soil: Volcanoes help in soil formation by bringing important minerals from from deep underground onto the earth’s surface.
6. Minerals: Volcanoes also bring valuable minerals to the earth’s surface.The minerals are important economic resources.

The Principle of Measurement

Earthquake warning signs

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere

1. The troposphere controls the climate and ultimately determines the quality of life on the earth.
2. The troposphere is important for life on earth. The layer contains gases which include oxygen which is used for respiration by animals and carbon dioxide which is used by plants in photosynthesis. The nitrogen found in this laye also provides an inactive environment for many chemical processes to take place. The gases also support many important chemical processes such as combustion, weathering and oxidation.
3. The stratosphere prevents harmful ultraviolet radiation from reaching the earth.
4. The mesosphere, thermosphere and exosphere also prevent harmful radiation such as cosmic rays from reaching the earth’s surface.
5. Communication is also made possible by some layers of the atmosphere, specifically the ionosphere.

1. Carbondioxide
2. Clearing and burning of vegetation
3. Burning of fossil fuel
4. Methane
5. Dinitrogen oxide
6. Chlorofluorocarbons(CFCs)

1. Increase in the temperature of the oceans.
2. Rise in sea levels.
3. Change in world’s climatic pattern.
4. Acidification of the oceans.
5. Extreme weather events.
6. Higher or lower agricultural yields.
7. Melting of Arctic ice and snowcaps. This cause landslides, flash floods and glacial lake overflow.
8. Extinction of some animal and plant species.
9. Increase in the range of disease vectors, that is organisms that transmit diseases.

Televisions

Cathode Ray Oscilloscopes

1. They travel in straight lines.
2. They readily penetrate matter.
3. They are not affected by electric or magnetic fields(they have no charge).
4. They cause fluorescence in certain substances.
5. They can be detected by photographic emulsion.
6. They ionise gases causing the gases to conduct electricity.

1. In the medical field
2. Crystallography
3. Astronomy
4. X-ray microscopic analysis
5. X-ray fluorescence
6. Security installations
7. Industries

1. Alpha rays or alpha particles are the positively charged particles.
2. Alpha particles have the least penetration power. They cannot penetrate the skin but this does not mean that they are not dangerous.
3. Since they have a great ionisation power, so if they get into the body they can cause serious damage. They have the ability of ionising numerous atoms a short distance. It is due to this reason that the radioactive substance that releases alpha particles needs to be handled with rubber gloves. It should not be inhaled, eaten or allowed near open cuts.

1. Beta particles are highly energetic electrons which are released from inside of a nucleus.
2. They are negatively charged and have a negligible mass.
3. Beta particles have a greater penetration power than the alpha particles and can easily travel through the skin.
4. Though beta particles have less ionisation power than the alpha particles but still they are dangerous and so their contact with the body must be avoided.

1. They have greatest power of penetration.
2. They are the least ionizing but most penetrating and it is extremely difficult to stop them from entering the body.
3. These rays carry huge amount of energy and can even travel through thin lead and thick concrete.

If an alpha-source is brought up close to the gauze it will ionise the air, and sparks will occur between the gauze and wire. With beta and gamma sources insufficient ions are usually produced for sparking to take place.The spark counter can be used to measure the range of alpha-particles.

Cloud chamber

• N₀ is the initial quantity of the substance that will decay (this quantity may be measured in grams, moles, number of atoms, etc).
• N(t) is the quantity that still remains and has not yet decayed after a time t.
• t_1⁄2 is the half-life of the decaying quantity.
• τis a positive number called the mean lifetime of the decaying quantity.
• λis a positive number called the decay constant of the decaying quantity.

Industrial Uses

Nuclear Power Plants

1. Nuclear activation: Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus often decays immediately by emitting gamma rays, or particles such as beta particles, alpha particles, fission products and neutrons (in nuclear fission). Thus, the process of neutron capture, even after any intermediate decay, often results in the formation of an unstable activation product. Such radioactive nuclei can exhibit half-lives ranging from small fractions of a second to many years.
2. Photonuclear reactions: A photonuclear reaction is a reaction resulting from an interaction between a photon and a nucleus.-During a photonuclear reaction energy of a gamma-ray photon is fully or partially absorbed by the nucleus forcing it into and excited state. From this excited state the nucleus can emit any particle, provided it has enough energy for such a process to occur. Most commonly it will emit a photon, but also a neutron (n), a proton (p) or an alpha (α) particle can be emitted.

1. Radiation safety:For physicians and radiation safety officers, activation of sodium in the human body to sodium-24, and phosphorus to phosphorus-32, can give a good immediate estimate of acute accidental neutron exposure.
2. Neutron detection:One way to demonstrate that nuclear fusion has occurred inside a fusor device is to use a Geiger counter to measure the gamma ray radioactivity that is produced from a sheet of aluminum foil.In the ICF fusion approach, the fusion yield of the experiment (directly proportional to neutron production) is usually determined by measuring the gamma-ray emissions of aluminum or copper neutron activation targets.Aluminum can capture a neutron and generate radioactive sodium-24, which has a half-life of 15 hours^[7][8] and a beta decay energy of 5.514 MeV. The activation of a number of test target elements such as sulfur, copper, tantalum and gold have been used to determine the yield of both pure fission and thermonuclear weapons.
3. Materials analysis:Neutron activation analysis is one of the most sensitive and accurate methods of trace element analysis. It requires no sample preparation and can therefore be applied to objects that need to be kept intact such as a valuable piece of art. Although the activation induces radioactivity in the object, its level is typically low and its lifetime may be short, so that its effects soon disappear. In this sense, neutron activation is a non-destructive analysis method.
4. The potential use of photo-nuclear reactions for a range of applications is described. These are: photo-nuclear transmutation doping of semiconductors, neutron production from electron linacs, quality checking of radioactive waste, fission product incineration, photo-excitation of isomers for dosimetry, and nuclear resonance fluorescence for materials analysis. Initial brief descriptions of atomic and nuclear interactions of photons are given.

• The size of the dose (amount of energy deposited in the body)
• The ability of the radiation to harm human tissue
• Which organs are affected

• Hair: The losing of hair quickly and in clumps occurs with radiation exposure at 200 rems or higher.
• Brain: Since brain cells do not reproduce, they won’t be damaged directly unless the exposure is 5,000 rems or greater. Like the heart, radiation kills nerve cells and small blood vessels, and can cause seizures and immediate death.
• Thyroid: The certain body parts are more specifically affected by exposure to different types of radiation sources. The thyroid gland is susceptible to radioactive iodine. In sufficient amounts, radioactive iodine can destroy all or part of the thyroid. By taking potassium iodide can reduce the effects of exposure.
• Blood System: When a person is exposed to around 100 rems, the blood’s lymphocyte cell count will be reduced, leaving the victim more susceptible to infection. This is often refered to as mild radiation sickness. Early symptoms of radiation sickness mimic those of flu and may go unnoticed unless a blood count is done. According to data from Hiroshima and Nagaski, show that symptoms may persist for up to 10 years and may also have an increased long-term risk for leukemia and lymphoma. For more information, visit Radiation Effects Research Foundation.
• Heart: Intense exposure to radioactive material at 1,000 to 5,000 rems would do immediate damage to small blood vessels and probably cause heart failure and death directly.
• Gastrointestinal Tract: Radiation damage to the intestinal tract lining will cause nausea, bloody vomiting and diarrhea. This is occurs when the victim’s exposure is 200 rems or more. The radiation will begin to destroy the cells in the body that divide rapidly. These including blood, GI tract, reproductive and hair cells, and harms their DNA and RNA of surviving cells.
• Reproductive Tract: Because reproductive tract cells divide rapidly, these areas of the body can be damaged at rem levels as low as 200. Long-term, some radiation sickness victims will become sterile.

Symptoms

First Aid

How to Protect yourself from Nuclear Radiation Hazards

• Time: An average the procedure time for a diagnostic coronary angiogram is approximately 30 minutes and an interventional procedure PCI or EPS/pacing would take between 90 to 120 minutes. However the fluoroscopic and the cine screening time are highly variable depending on the nature of the procedure and the experience of the operator. The lower the amount of time spent in a radiation area, the lower the exposure will be. Significant reductions can be achieved when an activity is delayed until after cine imaging is completed. Every effort should be made by the operating cardiologist in the cath lab to minimise fluoroscopy and cine screening time.
• Distance:Increasing the distance from the radiation beam decreases the risk of exposure. doubling the distance between the primary beam and operator, reduces the exposure by a factor of four. In addition, the radiation exposure varies according to the angle at which the camera is projected Oblique views (left and right anterior oblique) and steep angulations increase radiation exposure but are often employed to improve visualisation. 60-degree angulations give up to three times the operator dose than 30-degree angulations (11). The second operator or assistant is generally less exposed to radiation compared to the first operator but certainly more at risk than the other staff in the room.
• Shielding: Lead shields and shielding will significantly reduce the risk of exposure but only if appropriately used and in proper working order. Protective equipment includes lead aprons, thyroid collars and leaded glasses. With the newly designed frames and ultra light lenses, protective leaded eyewear is now used by more of the cardiologists and staff in cardiac cath lab. Some cath labs also use overhanging lead screens to prevent radiation exposure to brain. The staff should wear a protective apron of at least 0.25 mm lead equivalent. Protective gloves should be of at least 0.35 mm lead equivalent. All such protective clothing should bear an identifying mark and should be examined at yearly intervals. Defective items should be withdrawn from use.
• Adhering to guideline and protocols: Every unit or work place that deals with ionising radiation should have their own local guidelines and rules for radiation safety. These must be read, understood and strictly adhered to in daily practice. Staff must comply with these local rules in order to insure that the Trust and all their employees do not contravene statutory requirements of the ionising radiation regulations and other relevant legislation.
• Minimising risk of exposure to staff and patients: The occupational limit of radiation exposure in the UK currently is estimated at 20 mSv per year averaged over five consecutive years (5). Every operator who undertakes a cardiovascular procedure in the cath lab is responsible for the amount of radiation exposure to the patient, his or her co-staff and to themselves. In the event of an incident where the patient might have been exposed to inadvertent excess radiation either due to clinical circumstances, malfunctioning of the equipment or operation errors, the radiation protection adviser should be informed of the incident. It is their duty to estimate the radiation dose received by the patient and also advise whether the incident is to be reported.Only essential staff shall be in the cath lab during radiation exposure. All persons not required in the room should leave the room during serial radiographic exposure. The operator shall stand behind a barrier if possible. People who must move around the room during the procedure should wear a wraparound protective garment. When possible, the cardiologist and all other personnel required in the room should step back from the table and behind portable shields during cine and serial radiography procedures. This action can decrease the exposure of the cardiologist and the other nearby personnel by a factor of three or more (10).

1. Nuclear power plants to generate electricity for domestic and industrial use.
2. In making nuclear bombs.

When the currents are in the opposite directions, the fields between the conductors add up, while they cancel out on the outside. The field between them is stronger than on the outside. The resultant force is toward the outside of each conductor, hence repulsion.

The Mode of Action of a.c and d.c Generator

Consider a slinky wave as an example of a wave. When the slinky is stretched from end to end and is held at rest, it assumes a natural position known as the equilibrium or rest position.

A slinky

In the case of our slinky wave, the medium through that the wave travels is the slinky coils. In the case of a water wave in the ocean, the medium through which the wave travels is the ocean water. In the case of a sound wave moving from the church choir to the pews, the medium through which the sound wave travels is the air in the room.

Ocean water as the medium for water waves

1. Reflection
2. Refraction
3. Diffraction
4. Interference

The laws of reflection

1. The phenomenon of the reflection of sound is used to determine the distance between the two objects, for example depth of seabed, depth of cave or width of a valley. The type of sound used must be ultrasound.
2. Sonar (Sound Navigation and Ranging). Sonar is used to detect underwater objects (corals / fishes) or to determine the depth of the water by means of an echo. Sonar equipment emits a high frequency sound signal which is reflected by the object in the water. The reflected sound wave is received by the sonar receiver. The time taken for the echo to return is used to determine the distance of the object below the water surface. Sonar waves of high frequency is used because itpossessesmore energy, high penetration power and can travel further through water.
3. Reflection of light waves is used in the design of mirrors.
4. Detection of cracks in metals.
5. Determination of frequency of A.C’s.

Applications of interference of waves

1. Interference is applied when creating holograms. A hologram is a photograph of an interference pattern which is able to produce a three-dimensional image when suitably illuminated.
2. Destructive interference is used in noise reduction systems such as earphones.The system capture sound from the environment and use computer technology to produce a second sound wave,which leads to reduction in the loudness of the noise.
3. Concert halls and auditorium are usually designed in such a way to reduce the amount of destructive interference. Usually, the walls and ceiling made in such a way that they absorb rather than reflect sound.

• A transverse wave is one that vibrates at 90 degrees to the direction the wave is moving. For example, if you hold a Slinky between two hands and shake it up and down, you’ll get a wave that moves along the Slinky, but the vibrations will still be up and down. Underwater waves are also transverse.

• A longitudinal wave is one in which the vibrations are parallel to the direction the wave is moving. That’s like sending a pulse along the length of a Slinky, pushing it lengthwise. Instead of peaks and troughs, longitudinal waves have compression (areas where the Slinky is bunched together), and rarefaction (areas where the Slinky is spread apart). Another example of a longitudinal wave is a sound wave. Although you can’t see air molecules, if you could, you would notice that sound involves air molecules hitting each other, thereby producing areas with high densities of molecules (compression) and areas with low densities of molecules (rarefaction).

• Last of all, a surface wave is a wave that travels along the boundary between two materials. For example the kind of water wave you most often see–along the top of water–is an example of a surface wave. Surface waves move in similar ways to transverse waves but are a bit more complicated in their behavior.

• v =speed of a wave
• λ =wavelength
• f = frequency

• vibrating solids.
• rapid expansion or compression (explosions and implosions).
• Smooth (laminar) air flow around blunt obstacles may result in the formation of vortices (the plural of vortex) that snap off or shed with a characteristic frequency. This process is called vortex shedding and is another means by which sound waves are formed. This is how a whistle or flute produces sound. Also the aeolian harp effect of singing power lines and fluttering venetian blinds.

• Loudnessis the intensity of the sound which is the perceptual property. It is determined by the amplitude of sound wave and the number of auditory nerves activated by sound wave. Amplitude is a physical property determined by how much air pressure in a compression or rarefaction deviates from normal air pressure. The larger the amplitude the louder the sound.
• Pitch is an auditory sensation in which a listener assigns musical tones to relative positions on a musical scale based on the frequency of sound wave vibration. Frequency is an objective, scientific concept, whereas pitch is subjective. Sound waves themselves do not have pitch. It takes a human brain to map the internal quality of pitch.-Pitches are usually quantified as frequencies in cycles per second, or hertz.
• Timbre is the tone quality of sound produced by an instrument. It is referred to as sound quality or sound colour and it is a perceptual property. What makes a particular musical sound different from another, even when they have the same pitch and loudness.

1. Wind Instruments: This class of musical instruments requires you to blow into a specific wind instrument by following an order to ensure that the sound that you desire is produced. The instruments can be expected to work depending on the principles of frequencies, sound waves, acoustics, resonance and harmonics. The pitch of the produced sound when you start blowing the instrument is actually dependent on the length of the air column through which the waves of the sounds vibrate.Some of the most popular wind instruments are piccolo, flute, clarinet, shakuhachi, bassoon, oboe, accordion, English horn, harmonica, saxophone, pianica, bagpie and shehnai.
2. Percussion Instruments: These instruments require you to strike the surface of the instrument to generate vibrations to produce your desired note. Percussion instruments can actually be divided into two types. The first type includes tuned instruments that are known to produce a definite pitch or a series of different pitches. Some examples of the tuned percussion instruments include xylophone, vibraphone, marimba, tubular bells and timpani or kettle drum. The second type of percussion instruments is the indefinite pitch. Its examples include triangle, castanets, rattle, cymbals, tambourine, anvil and gong.
3. String Instruments: These are composed of those instruments that work based on sound wave vibrations produced by strings. The pitch that can be produced by these instruments is dependent on the length of air column and the type and thickness of strings used.Among the most popular string instruments are guitar, viola, violin, cello, mandolin, harp, double bass and banjo.

1. It is continuous i.e each band merges into the next and there are no gaps in the frequencies. The different kinds of radiation gradually change from one to another as their properties also gradually change.
2. In some case, there is an overlap in the range of wavelength. This is because sometimes the name given to the wave(radiation) is determined by the source and not the wavelength(or frequency) for example x-rays and γ -rays.

1. Fixed and mobile radio communication, broadcasting, radar and other navigation systems, communications satellites, computer networks and innumerable other applications.
2. Astronomers use large radio telescopes to collect and study radio waves from distant stars and galaxies. This helps them to determine composition, structure and motion of the celestial bodies.

1. In cooking
2. Radar systems
3. Long distance communication

1. Medical application the same as x-rays
2. In agriculture

1. X-ray photography
2. Diagnosis and treatment of cancer