physicsx2

Ok. Despite only five points, I still want to try to answer your questions.

QUESTION ONE
1st) Solar energy is generated by nuclear fusion inside the sun core.

(CORRECT, In chinese we called it as 核聚變. Fusion is to join two small nuclei to make a larger nucleus. Deuterium and Tritium combine together. A helium atom and a neutron is produced.

HOWEVER, the Fusion occurs at a very very high temperature. Luckily inside the sun the temperature is very high. In fact, inside the sun, Deuterium and Tritium already transform into plasma (HOT and ELECTRICALLY CHARGED GAS) In the plasma, electrons have been moved away from the atomic nuclei. For the positively charged ions to fuse, their temperature must be sufficient to overcome their natural charge repulsion. This is why we need a very high temperature.

The fusion process produce Helium atom, neutron and also Solar energy

2nd) Fusion of any two nuclei produces energy

CORRECT. Because fusion can produce energy, the solar energy can be produced from the fusion inside the sun. Hence, 2nd statement is the reason of 1st statement

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QUESTION TWO

1st: A coil of insulated wire is wound round an iron rod. When a high frequency a.c. is passed through the coil, the temperature of the iron rod rises

CORRECT. When a current passes through the coil, a magnetic field builds up. If an alternating current is there, the magnetic field is constantly changing. However, there is a iron core inside the coil. Whenever a magnetic field is build up by the coil, the molecule inside the iron core has to align with the magnetic field to give the required magnetic field.

However, the outside magnetic field is always changing due to ac current, then the polarity of the core has to move back and forth. due to the friction, the heat is generated inside the core. Actually it's called Hysteresis (磁滯)


2nd: When an a.c. current is passed through a coil, the magnetic lines of force inside the coil reverses their direction rapidly.

Correct. the magnetic field inside the coil can be regarded as presence of magnetic lines of force. The lines reverse their direction rapidly due to the high frequency ac

. But it's not the reason of 1st statement