Истории и востоковедения
A. Checking your understanding
жүктеу/скачать 1,14 Mb. Pdf көрінісі
|
| A. Checking your understanding
I. Give answers to the following questions: 1. Why are magnetism and electricity closely linked to each other? 2. What are the ammeter, voltmeter and galvanometer? 3. Which types of magnets are you familiar with? What are their peculiarities? 4. When do we use the right-hand rule? What does it state? 5. Which law allows the calculation of magnetic fields? II. There are several definitions in the text. What are they? Complete the sentences with the appropriate word(s). 1. A bar magnet attracts iron objects to its ends, called . 2. One end is the , and the other is the . 3. Magnetic field is expressed in SI units as a (T). 4. An is a current ‐measuring instrument constructed from a galvanometer movement in parallel with a resistor. 5. The magnetic field at any point is a . 72 III. Are these sentences true or false? 1. If two bar magnets are brought close together, the like poles will attract each other, and the unlike poles repel each other. 2. A current generates a magnetic field, and the field differs as the current is shaped into a loop, solenoid, toroid. 3. Magnetic field lines, not analogous to electric field lines, describe the force on magnetic particles placed within the field. 4. A loop of current in a magnetic field can experience a torque if it is free to turn. 5. The direction of the force may be found by the left ‐hand rule. IV. Think and answer. In summary, the electromagnetic field carries energy, linear momentum and angular momentum. It is thus appropriate to say that the electromagnetic field moves. The motion of the electromagnetic field can be visualized as the motion of its electric and its magnetic field lines. The motion of the electromagnetic field is described by a least action principle. The motion conserves energy and momentum. The motion is continuous, relative, reversible and mirror-invariant. We are directly led to ask: what is the nature of light then? V. Render the text into English. жүктеу/скачать 1,14 Mb. Достарыңызбен бөлісу:
|