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P6: Quiz 8 – Answers
P6: Quiz 8 – Answers
1)
a) The microwaves that microwave ovens produce are absorbed by the water molecules in the food resulting in energy being transferred to the thermal energy stores of the water molecules, thus causing the water molecules to heat up. The water molecules then transfer some of this thermal energy to the rest of the molecules in the food, which cooks the food. The microwaves are able to penetrate a small distance into the food before they are absorbed by the water molecules.
b) The microwaves used in microwave ovens have higher frequencies and shorter wavelengths
c) The atmosphere contains a lot of water vapour. The microwaves used to heat food are absorbed by water molecules, which means that they would be absorbed by the water molecules in the atmosphere and unable to reach satellites in space
d) Satellite TV works by a transmitter on earth transmitting microwaves into space where the microwaves are received by a receiver dish on a satellite. The microwaves that are sent into space are able to pass through the earth’s watery atmosphere. After the satellite has received the microwaves, it will transmit the signal back down to earth in a different direction where it is received by a satellite dish on the ground (such as a dish on the side of your house)
2)
a) The hotter identical object will emit more radiation
b) Infrared cameras work by detecting the infrared radiation given out by objects and converting it into an electrical signal. This electrical signal can then be viewed on a screen or as a picture. The hotter an object is, the more infrared radiation it will emit and the brighter it will appear on the image produced by the infrared camera
c) An electric heater has a long wire that heats up when a current passes through it. When the wire is hots, it emits large quantities of infrared radiation. This infrared radiation can be absorbed by the air and objects in the room, which transfers energy to the thermal energy stores of the air and objects, resulting in the temperature of the room increasing
d) No (humans cannot see infrared light)
3)
a) An arrow showing total internal reflection like what is shown below
a) The microwaves that microwave ovens produce are absorbed by the water molecules in the food resulting in energy being transferred to the thermal energy stores of the water molecules, thus causing the water molecules to heat up. The water molecules then transfer some of this thermal energy to the rest of the molecules in the food, which cooks the food. The microwaves are able to penetrate a small distance into the food before they are absorbed by the water molecules.
b) The microwaves used in microwave ovens have higher frequencies and shorter wavelengths
c) The atmosphere contains a lot of water vapour. The microwaves used to heat food are absorbed by water molecules, which means that they would be absorbed by the water molecules in the atmosphere and unable to reach satellites in space
d) Satellite TV works by a transmitter on earth transmitting microwaves into space where the microwaves are received by a receiver dish on a satellite. The microwaves that are sent into space are able to pass through the earth’s watery atmosphere. After the satellite has received the microwaves, it will transmit the signal back down to earth in a different direction where it is received by a satellite dish on the ground (such as a dish on the side of your house)
2)
a) The hotter identical object will emit more radiation
b) Infrared cameras work by detecting the infrared radiation given out by objects and converting it into an electrical signal. This electrical signal can then be viewed on a screen or as a picture. The hotter an object is, the more infrared radiation it will emit and the brighter it will appear on the image produced by the infrared camera
c) An electric heater has a long wire that heats up when a current passes through it. When the wire is hots, it emits large quantities of infrared radiation. This infrared radiation can be absorbed by the air and objects in the room, which transfers energy to the thermal energy stores of the air and objects, resulting in the temperature of the room increasing
d) No (humans cannot see infrared light)
3)
a) An arrow showing total internal reflection like what is shown below
b) A glass cladding to protect the glass centre
4)
a) A suntan
b) Skin cancer, sunburn, premature aging of the skin (wrinkles, leathery skin etc) and eye problems
c) The fluorescent chemicals absorb the UV radiation and reemit it as visible light
d)
i) Phosphor
ii) They are extremely bright and very energy efficient
e) We can use security pens to identify who owns property, such as a bike. The writing from security pens will not be visible under visible light, but will be visible under ultraviolet light as the fluorescent ink will absorb the UV rays and then remit it as light
5)
a)
i) No (X-rays are absorbed by bones)
ii) Yes (X-rays can pass through soft tissue)
b) The X-rays and gamma rays kill any microorganisms that are living on the food
c)
i) (Cancerous) tumours and internal bleeds
ii) The patient takes the medical tracer – usually they take it by swallowing it. The medical tracer will pass into the bloodstream and move around the body. Medical professionals follow the medical tracers progress around the body by looking for the gamma rays that are produced; they can use what is known as a PET scanner. Areas that have an internal bleed or a (cancerous) tumour will have a high blood supply, which means that they will have a lot of the tracer, thus meaning that large quantities of gamma radiation will come from these areas. The PET scanner will be able to locate and estimate the size of a (cancerous) tumour and internal bleeds
d)
i) Radiotherapy is used to treat people that have cancer; cancer is where the cells in part of the body are multiplying uncontrollable and it results in a growth or tumour. Individuals undergoing radiotherapy have beams of X-rays and gamma rays fired at the cancerous tumour. The X-rays and gamma rays kill the tumour cells which hopefully stops the tumour expanding
ii) When we undertake radiotherapy, we need to reduce the number of normal cells (non-cancerous cells) that are expose to the X-rays and gamma rays. This is because exposing normal cells to too much X-rays and gamma rays will result in the normal cells dying
4)
a) A suntan
b) Skin cancer, sunburn, premature aging of the skin (wrinkles, leathery skin etc) and eye problems
c) The fluorescent chemicals absorb the UV radiation and reemit it as visible light
d)
i) Phosphor
ii) They are extremely bright and very energy efficient
e) We can use security pens to identify who owns property, such as a bike. The writing from security pens will not be visible under visible light, but will be visible under ultraviolet light as the fluorescent ink will absorb the UV rays and then remit it as light
5)
a)
i) No (X-rays are absorbed by bones)
ii) Yes (X-rays can pass through soft tissue)
b) The X-rays and gamma rays kill any microorganisms that are living on the food
c)
i) (Cancerous) tumours and internal bleeds
ii) The patient takes the medical tracer – usually they take it by swallowing it. The medical tracer will pass into the bloodstream and move around the body. Medical professionals follow the medical tracers progress around the body by looking for the gamma rays that are produced; they can use what is known as a PET scanner. Areas that have an internal bleed or a (cancerous) tumour will have a high blood supply, which means that they will have a lot of the tracer, thus meaning that large quantities of gamma radiation will come from these areas. The PET scanner will be able to locate and estimate the size of a (cancerous) tumour and internal bleeds
d)
i) Radiotherapy is used to treat people that have cancer; cancer is where the cells in part of the body are multiplying uncontrollable and it results in a growth or tumour. Individuals undergoing radiotherapy have beams of X-rays and gamma rays fired at the cancerous tumour. The X-rays and gamma rays kill the tumour cells which hopefully stops the tumour expanding
ii) When we undertake radiotherapy, we need to reduce the number of normal cells (non-cancerous cells) that are expose to the X-rays and gamma rays. This is because exposing normal cells to too much X-rays and gamma rays will result in the normal cells dying
Questions
1) This question is all about microwaves.
a) We can use microwaves to cook food. Explain how microwaves cook food in a microwave oven.
b) Microwaves are also used in communication in satellites. What are the differences in frequency and wavelength between a microwave used for communication in satellites and a microwave used to cook food?
c) Explain why the microwaves used to heat up food would not be able to be used in communication with satellites.
d) Explain how microwaves are used in communication to send a message from earth to a satellite and back down to earth.
2)
a) If we have two identical objects that are different temperatures, will the cooler or hotter object emit more infrared radiation?
b) Explain how infrared camera work.
c) Explain how an electric heater uses infrared radiation to heat a room.
d) Can humans see infrared light?
3) Visible light is used in fibre optic cables to transport data across long distances. The diagram below shows what a fibre optic cable looks like.
1) This question is all about microwaves.
a) We can use microwaves to cook food. Explain how microwaves cook food in a microwave oven.
b) Microwaves are also used in communication in satellites. What are the differences in frequency and wavelength between a microwave used for communication in satellites and a microwave used to cook food?
c) Explain why the microwaves used to heat up food would not be able to be used in communication with satellites.
d) Explain how microwaves are used in communication to send a message from earth to a satellite and back down to earth.
2)
a) If we have two identical objects that are different temperatures, will the cooler or hotter object emit more infrared radiation?
b) Explain how infrared camera work.
c) Explain how an electric heater uses infrared radiation to heat a room.
d) Can humans see infrared light?
3) Visible light is used in fibre optic cables to transport data across long distances. The diagram below shows what a fibre optic cable looks like.
a) Part of the light ray travelling through the fibre optic cable is shown on the diagram above. Draw the rest of the light ray travelling through the fibre optic cable.
b) A fibre optic cable has a glass centre. What is the name and role for the bit around the glass centre of a fibre optic cable? There is an arrow on the above diagram pointing to the part of the fibre optic cable that I am on about.
4)
a) What can ultraviolet radiation from the sun in small doses give humans?
b) What are the effects on the human body if you are exposed to an excessive amount of UV radiation?
c) What do fluorescent chemicals do when they are exposed to UV radiation?
d)
i) What chemical do fluorescent lights contain?
ii) Give two advantages of using fluorescent lights as opposed to a filament bulb.
e) What are security pens and what use do they have?
5) X-rays are used to see internal structures inside the body.
a)
i) Can X-rays pass through bones?
ii) Can X-rays pass through soft tissue?
b) Why are X-rays and gamma rays used to sterilise food?
c)
i) Give two examples of medical conditions that we can use medical tracers to detect?
ii) Describe how medical tracers can be used to detect the conditions discussed in part c i.
d)
i) What is radiotherapy and explain how it is used to treat people with cancer.
ii) When we undertake radiotherapy, what do we need to be careful of?
b) A fibre optic cable has a glass centre. What is the name and role for the bit around the glass centre of a fibre optic cable? There is an arrow on the above diagram pointing to the part of the fibre optic cable that I am on about.
4)
a) What can ultraviolet radiation from the sun in small doses give humans?
b) What are the effects on the human body if you are exposed to an excessive amount of UV radiation?
c) What do fluorescent chemicals do when they are exposed to UV radiation?
d)
i) What chemical do fluorescent lights contain?
ii) Give two advantages of using fluorescent lights as opposed to a filament bulb.
e) What are security pens and what use do they have?
5) X-rays are used to see internal structures inside the body.
a)
i) Can X-rays pass through bones?
ii) Can X-rays pass through soft tissue?
b) Why are X-rays and gamma rays used to sterilise food?
c)
i) Give two examples of medical conditions that we can use medical tracers to detect?
ii) Describe how medical tracers can be used to detect the conditions discussed in part c i.
d)
i) What is radiotherapy and explain how it is used to treat people with cancer.
ii) When we undertake radiotherapy, what do we need to be careful of?