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- Marked by Teachers essays 11
- Peer Reviewed essays 13
This produces certain chemicals called 'tryptamines' which improve our mood The sun can be bad for you because... There are also many reasons why the sun can be bad for you, e.g: * Exposure to solar and artificial UV radiation is widely recognized as a leading and preventable cause of skin cancer. * Exposure to high levels of sunlight, makes it four times more likely for you to develop cataracts in your eyes. * Sunburn can change the distribution and function of disease-fighting white blood cells and damage our DNA.
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Although mobile phones use radio waves, some can be classed as microwaves. Prolonged exposure to microwaves is known to cause "cataracts" in your eyes, which is a clouding of the lens, preventing you from seeing clearly. Recent research indicates that microwaves from mobile phones can affect parts of your brain - after all, you're holding the transmitter right by your head. Other research is inconclusive, although there is a feeling that you're more vulnerable if you're young and your brain is still growing due to having a softer skull. Results which suggest that mobiles might damage health are actually rare.
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The frequency of a wave is measured as the number of complete back-and-forth vibrations of a particle of the medium per second. Unit of frequency is Hertz (Hz). The frequency of a wave can be altered by increasing the number of vibrations per second. Increasing the frequency, increases the pitch of the wave. Any sound that can heard by a human ear is called an infrasound (20Hz to 20000Hz). Above this range the sound is known as ultrasound. Ultrasound is used to communicate underwater because its can travel long distance without a lot of distortion.
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This force can be attractive and repulsive. If an electric current flows through a coil of wire a magnetic field is formed around the coil creating an electromagnet. This is a magnet which can be switched on and off. Here is a diagram which shows the magnetic fields around one turn of a coil To carry out this investigation I will follow the following steps: Insulated copper wire was coiled around a metal nail to make turns and then inserted into a power supply box.
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Investigating the factors which affect the sideways displacement of a light ray through a glass block.
5)Pencil (with a sharp point for grater accurately when plotting points and drawing lines) 6)Piece of white paper Diagram1: Experiment method: As shown in the diagram: I am going to place the glass block on a white piece of paper. I am going to draw around the glass block with the sharp pencil. On the paper I am also going to draw a normal (line 90 degrees to the glass block). By the help of the large-scaled compass, I am going to measure and then draw on the piece of paper 8 lines going from 10 to 80 degrees from the normal creating 8 different angles of incidence.
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A reflective layer is then applied to the surface of the polycarbonate using a process called sputtering. This is a shiny layer that is used to bounce the laser beam back to its original source. This means that this layer must have a very high integrity so that it remains in shape and not break apart. This reflective layer is usually made up of silver, but on occasions it is made up of gold or platinum. With a CD-R and CD-RW there is an extra photosensitive layer, this layer is very sensitive to different frequencies.
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Physics in the real world - During my visit to Broomfield Hospital I witnessed two aspects of physics in every day use. These were X-Rays and ultrasound; they both do similar jobs, although they both have limitations.
Ions can then collide with more atoms to create more ions. This can cause defects in strands of DNA, this can either cause cancerous cells or, it can kill off the DNA making the patient ill. Prolonged exposure to X-Rays causes Radiation sickness. Which is why the operators of X-Ray machines stand behind lead shields. X-Rays are wavelike forms of electromagnetic radiation, very much like visible light. The difference between the two is the wavelength; X-Rays have a much shorter wavelength. They also have a very high energy level and can pass through most things. X-Ray machines work by beaming X-Rays through a series of filters, then on to the patient.
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Speed = Frequency x Wavelength v = f ? Hutchings: Q 11.1 and 11.2 p 164. 2.2.6 Transverse and Longitudinal Waves. Waves may be produced by two distinct forms of vibration. We may thus classify any wave as being a TRANSVERSE WAVE or a LONGITUDINAL. Tranverse Wave. eg. Water waves, some Seismic waves and ALL Electromagnetic waves. Vibration causing disturbance is at right angles to the direction in which the energy travels Longitudinal Waves. eg. Sound waves and some Seismic waves.
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* Simple and inexpensive hardware implementation suitable for portable players and recorders. When digital audio data is compressed, there is normally a certain amount of quantization noise introduced into the signal. The goal of many audio coding systems [1-6] is to control the time-frequency distribution of this noise in such a way as to render it inaudible to the human ear. If this is completely successful, the reconstructed signal will be indistinguishable from the original. In general, audio coders operate by decomposing the signal into a set of units, each corresponding to a certain range in time and frequency.
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Figure 1 ? Figure 2 ? SPL meter as it was used in the application I performed some preliminary experiments to determine: * The distance between the SPL meter and the speaker. * The frequency of the signal the speaker should emit. * The lowest amplitude that could be sensed by the SPL meter. * The highest amplitude that could be produced by the signal amplifier. I found: * For the SPL meter to register at low amplitudes the furthest distance the speaker can be from the sensor is 3.5cm.
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That is, my independent variable will be current through the coil. It will be found what effect currents of different sizes will have upon the strength of the electromagnet, by measuring the force exerted by it using a Newton Meter, when different currents are passed through the electromagnet. The magnetic force exerted by the electromagnet is my dependent variable. In this experiment a large iron rod will be used as the core and a wire (Constantan, with insulation) will be coiled around it, to make the electromagnet.
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This is then repeated all the way to the end of the cable where the information is needed. Practical applications include digital audio transmitters which allow CD quality sound to be sent from one place to the other, with hardly any loss of quality. Other applications include Cats Eyes which are reflective road markings. These employ total internal reflection to give drives a better idea of where the road markings are, when driving in the dark. The Cats Eye works by reflecting the light from the cars head lamps through 180� and back to the eyes of the driver to alert him or her when the centre of the road is.
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There are two main ways by which the health is directly jeopardized by the RF radiation. These are by thermal effects caused mainly by holding the mobile phone close to the body and non-thermal effects, which are caused by both the phone itself and the base stations that emits the signal. Moreover there are other reasons that might affect the general population, like there is strong evidence relating the use of mobile phones whilst driving increases the probability of a car accident.
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The greater the number, the slower light passes through the substance. Here are some other refractive indexes for other materials: Substance Refractive Index Speed of light Air 1.0 300,000,000 Water 1.33 225,000,000 Perspex 1.5 200,000,000 Glass 1.5 200,000,000 Diamond 2.4 120,000,000 There is another way to find the refractive index of a substance. The formula for this is: Refractive Index = Sine i Sine r This rule is called Snell's Law. Angle i is the angle of incidence and angle r is the angle of refraction.
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Scientific Explanation of my prediction The scientific explanation of this is that within electromagnets there are domains (see below), which are very small magnets within the iron core (the smallest are each 1/1000th of a mm). When no current is passing through the coils, the domains all face in different directions, so the core is not magnetic. However when current is applied through the coils, the domains begin to face in the same direction, thus making the core magnetic. The more domains are turned, the easier it is for other surrounding domains to be turned by the coils.
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