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Frage | Antworten |
Describe the term efficiency | Efficiency is the proportion of energy transferred to useful forms |
Explain the condition needed for something to keep at a constant temperature |
The average power absorbed = the average power radiated
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Explain how an electric current is induced by a magnet and wire |
Movement so the wire cuts the magnetic field lines, which induces a voltage, which induces a current
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Describe Galileo's observations and explain how they changed our ideas of the universe | Galileo saw 4 moons orbiting Jupiter. This disproved the geocentric theory because it showed that not everything orbited the Earth |
Recall the life cycle of a star the similar in mass to our sun
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Nebula -> Main Sequence -> Red Giant -> White Dwarf -> Black Dwarf |
Recall the life cycle of a star with a greater mass then our sun | Nebula -> Main Sequence -> Super Red Giant -> Supernova -> Black hole or Neutron star |
Describe how potential danger is related to the frequency of a wave
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As the frequency of a wave increases its potential danger also increases |
Explain how to measure the focal length of a lens | Measure the distance between the focal point and the lens |
Describe what happens to all waves at a boundary between different materials |
The waves are refracted and reflected
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Recall what ionising radiations are emitted by | Ionising radiations are emitted by radioactive sources |
Describe the term redshift | Redshift is the increase in wavelength of light of an object moving away from the observer |
Describe the terms current and voltage | Current is the rate of flow of charge/flow of electrons and voltage is the electrical pressure/measure of energy transferred |
Describe what all waves do and do not transfer | All waves transfer information and energy but do not transfer matter |
Describe the dangers of microwave, infra-red and ultraviolet radiation | Microwave: internal heating of body cells. Infra-red: skin burns. Ultraviolet: damage to surface cells and eyes, leading to skin cancer and eye conditions. |
State the people discovered IR and UV and describe their experiment | Herschel discovers IR using thermometers that showed a greater temperature rise beyond the red end of the spectrum. Ritter discovered UV using silver chloride paper that turned black quickest beyond the violet end of the spectrum |
Recall the shared properties of all EM waves | All EM waves are transverse and travel and the same speed in a vacuum |
Explain why waves refract at a boundary between different materials | The waves change speed because they move into a more dense or less dense material |
State the evidence that supports the big bang theory | The big bang theory is supported by redshift and the CMBR (cosmic microwave background radiation |
Explain why some telescopes are located outside the earths atmosphere | No absorption of light by the atmosphere and no light pollution/cloud cover |
Describe the three advantages of modern telescopes | They use other parts of the EM spectrum, they can be connected to computers to store large amount of data, they have a larger magnification to view faint objects |
Explain how a main sequence star is formed from a nebula | Nebula is pulled in by gravity. The temperature increases until it is hot enough to fuse hydrogen to helium |
State what causes the motion of tectonic plates | Convection currents in the mantle |
Describe the terms ultrasound and infrasound | Ultrasound are sound waves with frequencies above 20,000 Hz. Infra-sound are sound wave with frequencies below 20 Hz |
Explain why step-up transformers are used in the transmission of electricity | The step-up transformer increase the voltage of electricity. This lowers the current and reduces heat lost in the power lines which increases the efficiency of energy transmission |
Describe how to calculate payback times | Payback time = Total cost / savings per year |
List the waves of the electromagnetic spectrum in order of increasing frequency/decreasing wavelength | Radio waves, microwaves, infrared, visible light, ultraviolet x-rays, gamma rays |
Explain why the Big Bang theory is more accepted then the steady state theory | The Big Bang theory is supported by both redshift and the CMBR where as the steady state theory is only supported by redshift |
Describe law of conservation of energy | Energy cannot be created or destroyed, it can only be transformed |
Explain how data from seismometers can be used to identify the location of an earthquake | Arrival of the P-wave and S-wave is timed, distance of the earthquake is calculated using time difference between the two waves, information from three seismometers is used to pinpoint the earthquake (triangulation). |
Explain how earthquakes are caused at plate boundaries | Convection currents in the mantle move the tectonic plates. Friction causes pressure to build up between the plate. Sudden movement (jolt/jerk/slip) of the plates releases energy causing an earthquake |
Describe the term Power and state its units | Power is the energy transferred per second and it is measured in watts |
State how scientists use waves to find out information about our Universe | Using the naked eye, photography and telescopes. |
Define the term amplitude | Amplitude = distance from the baseline of zero displacement to the point of maximum displacement (to top of crest or to bottom of trough) |
Define the term wavelength | One wavelength (m) = distance of one complete cycle or oscillation = horizontal distance from any point on the wave until where it begins to repeat = distance between two crests = distance between two troughs |
Define the term frequency | Frequency of a wave (Hz) = number of complete cycles/oscillations per second = number of complete waves passing a given point per second. |
Describe the differences between longitudinal and transverse waves | Transverse wave the oscillations are perpendicular (at 90 degrees) to the direction of energy transfer, but in a longitudinal wave the oscillations are parallel to the direction of energy transfer |
Identify sound, electromagnetic and seismic waves as transverse or longitudinal. | Electromagnetic waves - transverse only Sound waves - longitudinal only Seismic waves - can be of both types of wave |
State the order of the visible spectrum | red, orange, yellow, green, blue, indigo, violet (Roy G. Biv) |
Describe some uses of radiowaves | radio waves: broadcasting, communications and satellite transmissions |
Describe some uses of microwaves | microwaves: cooking, communications and satellite transmissions |
Describe some uses of infrared | infra-red: including cooking, thermal imaging, short range communications, optical fibres, television remote controls and security systems |
Describe some uses of visible light | visible light: including vision, photography and illumination |
Describe some uses of ultraviolet | ultraviolet: including security marking, fluorescent lamps, detecting forged bank notes and disinfecting water |
Describe some uses of x-rays | X-rays: including observing the internal structure of objects, airport security scanners and medical X-rays |
Describe some uses of gamma rays | gamma rays: including sterilising food and medical equipment, and the detection of cancer and its treatment |
State ionising radiation from the nucleus of an atom | Ionising radiation includes alpha and beta particles and gamma rays. |
State the name of the galaxy that the Solar System is part of | the Solar System is part of the Milky Way galaxy |
Define a galaxy | A galaxy is a collection of stars |
Define the Universe | The Universe includes all of the galaxies |
Describe the methods used to gather evidence for life beyond Earth | Space probes, soil experiments by lunar/planetary landers and Search for Extraterrestrial Intelligence (SETI) |
Explain what is meant by the CMBR (cosmic microwave background radiation) | The CMBR (cosmic microwave background radiation) is the energy remnant left over from the big bang. |
Explain why the red-shift of galaxies provides evidence for the Universe expanding | Red-shift tells us that galaxies are moving away. Almost all galaxies show red shift, which means that they are all moving away. This tells us the universe must be expanding |
Describe some uses of ultrasound | a) sonar b) communication between animals c) foetal scanning |
Describe uses of infrasound | a) communication between animals b) detection of animal movement in remote locations c) detection of volcanic eruptions and meteors |
State two ways that seismic waves are generated | Seismic waves are generated by earthquakes or explosions |
Explain why scientists find it difficult to predict earthquakes and tsunami waves even with available data. | We do not know when the tectonic plates will slip, making earthquakes and tsunamis unpredictable. |
Describe the factors that affect the size of an induced current | a) stronger magnet b) faster spinning/movement c) more turns on the coil of wire |
State the main forms of energy | thermal (heat), light, electrical, sound, kinetic (movement), chemical, nuclear, potential (elastic), potential (gravitational). |
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