electrons are emitted when ......?

Question

i wanna know the various substances that emit electrons when some conditions are made available. So i wanna know the substances with which electrons are emitted when
(i) Heat is supplied to it?
(ii) Light is incident upon it?
(iii) Wind graces it?
(iv) It is kept in water?
(v) Sound reception is provided?
(vi) And by any other mechanical source?

I Know that a single substance wont exhibit all these (If anyone does than plz tell me) so even if u know six different substances for the six conditions then its perfectly O.K. . Please help me out. Its very urgent and if u know a site related to this then plz give me its address. THANK YOU

with wind i dont just mean when it faces air, actually i want to know, is there an apparatus that runs with the help of wind and releases electrons???????

Answer 1

1. 2 wires of different materials twisted togther (example, iron and copper twisted together, keeping one end at a constant temperature, heating the other. Some thermometers use this property)

2. Solar cells.

3. Water in clouds (the gradual build-up of collections of charges due to electron emission results to lightning bolts)

4. Sodium (which is why sodium will react explosively with water)

5. Piezoelectric materials (example, quartz. Some microphones use this principle)

6. A comb and a piece of woolen cloth rubbibg agains each other. (The emission of electrons will cause both the comb and the cloth to gain a charge (opposite of each other, but the same strength), which will enable it to pick up small pieces of paper)

Answer 2

Cathodes are made out of a variety of materials based upon use: Iron, aluminum and exotics like titanium diboride.

Selinium materials are used in photoelectrics. As with transistors the selinium generally needs to have materials like arsenic added to create holes and electron points. Then the wavelength of the light causes the electroncs to flow to the holes.

tourmaline, quartz, topaz, cane sugar, and Rochelle salt, quartz analogue crystals like berlinite (AlPO4) and gallium orthophosphate (GaPO4), ceramics with perovskite or tungsten-bronze generate Piezoelectricity when mechanical tension or force is generated.

Not sure about water or air.

Salt water might react with certain metals to create electron flow, but plain water, not sure.

Answer 3

(i)thermoionic effect
(ii)photoeletric effect
(iii)thermal agitations
(iv)electrolysis
(v)pizoelectric effect
(vi)converse of pizo electric effect