______ when electron rearrangement takes place.
第2题
One can get a sunburn even________
A.when it is absorbed by matter
B.when it is cloudy
C.because they can pass through solid objects D when the sunrays are fierce
E.when a change in the nucleus of an atom takes place
F.when electron rearrangement takes place
第3题
Electromagnetic Energy
White light seems to be a combination of all colors. The energy that comes from a source of light is not limited to the kind of energy you can see. Heat is given off by a flame or an electric light. On a cloudy day it is possible to get a sunburn even though you feel cool. Visible light and the kind of energy that produce warmth and sunburn are examples of electromagnetic energy.
The sun is 93 million miles from the earth. Yet we can use energy from the sun because electromagnetic energy travels through space.
Many other kinds of energy are also types of electromagnetic energy. Radio, television, and radar
signals travel from transmitters to receivers as low-energy electromagnetic waves. Infrared (红外线的) radiation is an electromagnetic wave. When it is absorbed by matter, heat is produced. Waves of infrared and visible light have more energy than waves of radio, television, or radar. Ultraviolet rays (紫外线) and X-rays are electromagnetic waves with even greater amounts of energy. Infrared radiation is used in cooking food and heating buildings. Sunlight and electric lights are part of our requirements for normal living. Ultraviolet radiation is useful in killing certain disease organisms. X-rays and gamma rays have so mush energy that they travel right through solid objects. They can be used to detect and treat cancer. X-rays are used in industry to find hidden cracks in metal, and in medicine to reveal broken bones. Usually we use electricity to generate electromagnetic energy. The source of most of our energy is the sun. Heat from the sun causes water to evaporate. When the water falls to the earth as rain, some of it is trapped behind dams and then used to operate electric generators. Other generators are powered by coal, but the energy stored in coal came from the sun, too.
Until recently, the source of the tremendous amount of energy given off by the sun was a puzzle. If the sun depended on chemical reactions, it would have used up all its energy long ago. Experiments with electromagnetic radiation led to the theory that mass can be converted into energy. About forty years after the theory was proposed, nuclear energy was harnessed (利用) by man. Chemical energy comes from electron (电子) rearrangement. Nuclear energy comes from a Change in the nucleus of an atom. Compared with chemical reactions, nuclear reactions release millions of times more energy per pound of fuel. We now believe that the sun&39;s energy comes from the nuclear reactions in which hydrogen is changed into helium (氦).
Nuclear energy is beginning to compete with coal as an economical source of power to generate electricity. It is also being used to operate engines in large ships. Scientists continue to seek new and better methods of obtaining and using energy.
Paragraph 3 ______.
A. Nuclear reactions as the lasting source of the sun&39;s energy.B. The most important source of energy.C. Types of electromagnetic energy.D. The machines used for energy generation.E. Seeking new sources of energy. F. The use of ultraviolet radiation in medicine.
Paragraph 4 ______.
A. Nuclear reactions as the lasting source of the sun&39;s energy.B. The most important source of energy.C. Types of electromagnetic energy.D. The machines used for energy generation.E. Seeking new sources of energy. F. The use of ultraviolet radiation in medicine.
Paragraph 5 ______.
A. Nuclear reactions as the lasting source of the sun&39;s energy.B. The most important source of energy.C. Types of electromagnetic energy.D. The machines used for energy generation.E. Seeking new sources of energy. F. The use of ultraviolet radiation in medicine.
Paragraph 6 ______.
A. Nuclear reactions as the lasting source of the sun&39;s energy.B. The most important source of energy.C. Types of electromagnetic energy.D. The machines used for energy generation.E. Seeking new sources of energy. F. The use of ultraviolet radiation in medicine.
One can get a sunburn even ______.
A. when it is absorbed by matterB. when it is cloudyC. because they can pass through solid objectsD. when the sunrays are fierceE. when a change in the nucleus of an atom takes place F. when electron rearrangement takes place
Infrared radiation can produce heat ______.
A. when it is absorbed by matterB. when it is cloudyC. because they can pass through solid objectsD. when the sunrays are fierceE. when a change in the nucleus of an atom takes place F. when electron rearrangement takes place
X-rays and gamma rays can be used to detect and treat cancer ______.
A. when it is absorbed by matterB. when it is cloudyC. because they can pass through solid objectsD. when the sunrays are fierceE. when a change in the nucleus of an atom takes place F. when electron rearrangement takes place
Chemical energy is generated ______.
A. when it is absorbed by matterB. when it is cloudyC. because they can pass through solid objectsD. when the sunrays are fierceE. when a change in the nucleus of an atom takes place F. when electron rearrangement takes place
请帮忙给出每个问题的正确答案和分析,谢谢!
第4题
Electromagnetic Energy
?? 1. White light seems to be acombination of all colors. The energy that comes from a source of light is notlimited to the kind of energy you can see. Heat is given off by a flame or anelectric light. On a cloudy day it is possible to get a sunburn even though youfeel cool. Visible light and the kinds of energy that produce warmth andsunburn are examples of electromagnetic energy.
?? 2. The sun is 93 millionmiles from the&39;earth. Yet we can use energy from the sun because electro-magnetic energy travels through space.
?? 3. Many other kinds ofenergy are also types of electromagnetic energy. Radio, television, and ra- darsignals travel from transmitters to receivers as low-energy electromagneticwaves. Infrared (红外线的) radiation is an electromagnetic wave. When it is absorbed by matter,heat is produced. Waves of infrared and visible light have more energy thanwaves of radio, television, or radar. Ultraviolet rays(红外线) ahd X-rays areelectromagnetic waves with even greater amounts of energy. Infrared radia- tionis used in cooking fo??od?? and heating buildings. Sunlight and electric lights arepart of our require- ments for normal living. Ultraviolet radiation is usefulin killing certain disease organisms. X-rays and gamma rays have so much energythat they travel right through solid objects. They can be used to de- tect andtreat cancer. X-rays are used in industry to find hidden cracks in metal, andin medicine to re-veal broken bones.
?? 4. Usually we useelectricity to generate electromagnetic energy. The source of most of our energyis the sum Heat from the sun causes water to evaporate. When the water falls tothe earth as rain, some of it is trapped behind dams and then used to operateelectric generators. Other generators are powered?? by coal, but the energystored in coal came from the sun, too.
?? 5. Until recently, thesource of the tremendous amount of energy given off by the sun was a puz- zle.If the sun depended on chemical reactions, it would have used up all its energylong ago. Experi- ments with electromagnetic radiation led to the theory thatmass can be converted into energy. About forty years after the theory wasproposed, nuclear energy was harnessed (利用) by man. Chemical en- ergy comes from electron (电子) rearrangement. Nuclear ene??rgy comes from a change in the nucleus of anatom. Compared with chemical reactions, nuclear reactions release millions oftimes more energy per pound of fueL Wenow believe that the sun&39;s energy comes from the nuclear reactions in which hy-drogen is changed into helium (氦).
?? 6. Nuclear energy isbeginning to compete with coal as an economical source of power to generate, electricity.It is also being used to operate engines in large ships. Scientists continue toseek new and better methods of obtaining and using energy.??
Paragraph 3_______??
??Paragraph 4____??
??Paragraph5___??
??Paragraph 6_________??
??Visible light that produce warmth is an example of_____??
??We can use energy from the sun because________??
??The energy stored in coal_______.??
??___________when electron rearrangement takes place??
请帮忙给出每个问题的正确答案和分析,谢谢!
第7题
电镜三维重构技术(electron microscope three-dimentional reconstruction technique)
第8题
“电子商务”的英文说法是()。
A、Electron Commerce
B、Electronic Commerce
C、Electronics Commerce
D、Electronic Contract
第10题
A) that
B) this
C) which
D) it