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ser-zykov [4K]
3 years ago
12

If temp. gets cold resistance in thermostat increases so voltage across it increases AND LED lights brighter. I understand every

thing except that for LED. It emits light when current passes through it, but if resistance increases how can current increase???​

Physics
1 answer:
Valentin [98]3 years ago
5 0

Normally, when something gets colder, its electrical resistance gets smaller.  This is true of component-A in the drawing ... a simple resistor.

The component labeled 'B' has a strange and unusual symbol, and it's not a simple resistor.  It's a "thermistor".  The word "thermal" always has something to do with heat, and "thermistor" comes from "thermal resistor.  These things can be manufactured either way ... using different materials, a thermistor can be manufactured so that its resistance goes UP, or goes DOWN, or doesn'tchange when it gets colder.  I'm pretty sure that's what's going on here.

When this circuit gets colder, resistance-A gets smaller, but resistance-B either gets bigger OR doesn't change.  Either way, the voltage across B increases.  Since the LED is connected directly across B, the current through it depends on that voltage, so the LED gets more current, and becomes brighter, when A and B both get colder.

This circuit could actually be a very useful device.  If you took out the LED and put a voltmeter in its place, then the reading on the voltmeter would tell you the temperature of wherever you put the two components A and B.

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Two energy transfers take place when a book hits the ground, Which type of energy transfers are those
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Answer:

I think that when a book hits the ground its potential energy converts into kinetic energy and then kinetic energy is transformed into sound and heat energy.

Explanation:

6 0
3 years ago
when do you use cos and sin in situations like these? is horizontal always cos and vertical always sin?
Andreas93 [3]

Answer:

yes

Explanation:

this is simple

the horizontal line is adjacent

the vertical line is opposite

recall that cos x=adj/hyp

adj=hyp(cos x)

while opp=hyp(sin x)

8 0
3 years ago
Why is it important that two different metals are used in building an electrochemic<br> cell?
Mnenie [13.5K]

Answer:

Explanation:

They need a galvanic difference. Or saying that less technically,  they need to have different electron attraction, so that one can collect electrons (oxidation/reduction)  and flow current from the other.  :)

5 0
3 years ago
In the presence of ________, hydrogen peroxide will decompose into oxygen and water.
IrinaK [193]

Answer: Catalase enzyme

Explanation:

The catalase is an enzyme that is commonly found in the living organisms that are exposed to minute or high amount of oxygen or those in which aerobic respiration takes place.

This enzyme catalyzes the breakdown or decomposition of the hydrogen peroxide into oxygen and water. In humans and animals the catalase is present in liver, where it conducts the function of detoxifying the body by decomposing the toxins.

7 0
3 years ago
The height a ball bounces is less than the height of the previous bounce due to friction. The heights of the bounces form a geom
AlladinOne [14]

Answer:

Explanation:

Let the first height be h . second height .75h

third height .75h . fourth height .75²h

fifth height .75²h , sixthth height .75³ and so on

Total distance consists of two geometric series as follows

1 ) first series

h + .75h + .75²h + .75³h......

2 )  second series

.75h +.75²h +.75³h + .75⁴h .......

Sum of first series :

first term a = h , commom ratio r = .75

sum = a / (1 - r )

= h / 1 - .75

= h / .25

4h

sum of second series :--

first term a = .75 h , commom ratio r = .75

sum = a / (1 - r )

= .75h / 1 - .75

= .75h / .25

3h

Total of both the series

= 4h + 3h

= 7h .

h = 1 m

Total distance = 7 m

6 0
3 years ago
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