Its C
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Answer:
The movement of electrons in the presence of a magnetic field.
Explanation:
cathode-ray tube (CRT) has to do with
a vacuum tube in which an electron beam is deflected by applying electric or magnetic fields, produces a trace on a fluorescent screen. Cathode-ray tubes are uses in the television (TV) display. Other uses include radar displays, oscillography, and visual displays for computer terminals.
The discovery of gallium was significant as it confirmed Mendeleev’s predictions and showed the usefulness of his table.
Answer: Option First
<u>Explanation:
</u>
In 1871, Mendeleev prepared a periodic table of all known elements to study their properties. While making the table, he left some places in the table for elements that were yet to be discovered. One of the elements was eka-aluminium.
In 1875, a French scientist Paul Emile Francois Lecoq de Boisbaudran discovered a new element spectroscopically in the course of examining zinc blende. This newly discovered element showed the same properties as predicted by Mendeleev for the eka-aluminium with an atomic weight 69.
Later, the specific gravity of the element was also found to be the same as predicted by Mendeleev i.e. 5.9. After this, Lepoq named the element as Gallium, which confirmed Mendeleev’s predictions and made his periodic table worthier.
Explanation:
It is given that,
Height of the object, h = 17 cm
Object distance, u = -75.5 cm
Focal length of the concave mirror, f = -39 cm
We need to find the height if the cup's mirror image. Let v is the image distance. Using mirror's equation as :
v = −80.67 cm
Let h' is the magnification of the mirror. The magnification of mirror is given by:
h' = −18.16 cm
So, the image of cup is 18.16 cm tall and it is inverted. Hence, this is the required solution.