Author Topic: Physics Help HERE ONLY !!  (Read 80839 times)

Offline SGVaibhav

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Offline Shogun

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Re: Physics Help HERE ONLY !!
« Reply #196 on: May 29, 2009, 12:41:22 pm »
Can somebody plz explain me
1) Thermistor
2)Transistor
3) Diode Rectification
4) LDR

hi,thermistor is a type of a resistor, except tht it works depending on the temperature. if the temperature was at cold the resistance increases, and as resistance increases the current is acroos it reduces.
so in short the lower the temperature the higher the resistance.

now, the transistor, u see, is an elctronic switch, an automatic switch u see, it has 3 sets of wire joind as a circuit, the 3 wires are base,collector and emitter.it allows somthing (eg: a lamp) to work depending on 2 condition which are: 1) there must be a current on the base wire(ie. there must be a base current)
                            2)the potential difference(P.D) betwwen base and emitter path must be atleast 0.6volts.
if these 2 conditions are not there then the lamp is automatically switched off.

then therez the diode, its positive side must be connected to the positive side of the battery(the same was the ammeter is connected)  then it will allow current to flow throgh (i.e no resistance). what is its job? it changes an AC current to DC.Now, if the positve side of this device is connected to the negative side of the battery the resistance would be high and would not conduct electricity(i.e it wont allow current to pass).

then finally the light dependant resistor(LDR). this thing is like the thermistor...except it depends on light.if light falls on it the resistance decreases thus allowing current to pass, in short, if light touches it the resistance decreases.

hope u understand, any difficulties, or problems, or confusion u have plz do ask me.
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Offline cactus_360

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Re: Physics Help HERE ONLY !!
« Reply #197 on: May 29, 2009, 03:22:41 pm »
can anyone explain potential divider briefly.................
Newtons (pimped) Law: Every BOOK continues to be in a state of rest or uniform motion UNLESS and UNTIL  an External or Internal exams COME!!!!!!!!!!!!

Offline leebux101

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Re: Physics Help HERE ONLY !!
« Reply #198 on: May 29, 2009, 03:45:51 pm »
potential divider is like a variable resistor...u can vary the voltage tht is being provided to one device and the other as well according to the voltage tht is need for the devices...or just vary the voltage and resistance and compare current and stuff like tht...
i am not sure abt this...u shud ask someone else just in case...
good luck!

Offline Shogun

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Re: Physics Help HERE ONLY !!
« Reply #199 on: May 29, 2009, 04:16:30 pm »
can anyone explain potential divider briefly.................

yup wat bakhtawar said was correct, it devides the voltage accross the circuit to parts or devices.
for eg: this much voltage1 for device 1 and this voltage2 is for device2,what does the potential devider do is tht it can take some voltag1 to voltage2 so now device2 has more voltage. its job is to devide the voltage.
one who masters both the pen and paper is indeed a true warrior.

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Offline sweetsh

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Re: Physics Help HERE ONLY !!
« Reply #200 on: May 29, 2009, 04:57:19 pm »
What is a permanent magnet?! And why is steel used to make it?

Offline Shogun

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Re: Physics Help HERE ONLY !!
« Reply #201 on: May 29, 2009, 05:16:52 pm »
a permanent magnet have those magnetic ability to attract and repel forever. this what i call "magnetic power" lol.. and steel u see reatins tht magnetism forever after being put through a solenoid and is magnetized. however iron(wounded in a solenoid) looses tht magnetism directly after current is switched off on the solenoid...

hope u understand
one who masters both the pen and paper is indeed a true warrior.

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Offline sweetsh

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Re: Physics Help HERE ONLY !!
« Reply #202 on: May 29, 2009, 05:19:55 pm »
So iron doesnt attract and repel forever?
And thank you.

Offline Shogun

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Re: Physics Help HERE ONLY !!
« Reply #203 on: May 29, 2009, 05:21:55 pm »
yup iron wont repel or attract forever,unless its under a solenoid with current passin through it forever
one who masters both the pen and paper is indeed a true warrior.

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Offline Summer :]

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Re: Physics Help HERE ONLY !!
« Reply #204 on: May 29, 2009, 05:35:18 pm »
hey does anybody have notes to do with magnestism,generators,motors??? my weakness :-\

Offline X Abdulrahman X

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Re: Physics Help HERE ONLY !!
« Reply #205 on: May 29, 2009, 05:43:02 pm »
hey does anybody have notes to do with magnestism,generators,motors??? my weakness :-\

http://www.physclips.unsw.edu.au/jw/electricmotors.html
Enjoy :)
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What they say about me doesn't make me mad 
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Offline Summer :]

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Re: Physics Help HERE ONLY !!
« Reply #206 on: May 29, 2009, 06:51:36 pm »
hey does anybody have notes to do with magnestism,generators,motors??? my weakness :-\

http://www.physclips.unsw.edu.au/jw/electricmotors.html
Enjoy :)

Thankyouuuuuuuuuuuuuuu!!!! :D :D
have u got any idea how a thermocouple thermometer works?? :P and umm i have a few questions about
Linearity of the thermometers, what does it mean??

Offline islu_jf

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Re: Physics Help HERE ONLY !!
« Reply #207 on: May 29, 2009, 06:55:44 pm »
Can u pleeeeeeeeeeeeeeeezzz tel me what is LDR and and the light emittng one.. what are they used for??????

Offline cactus_360

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Re: Physics Help HERE ONLY !!
« Reply #208 on: May 29, 2009, 06:57:28 pm »
linearity means that distance between each degree on da scale is the same!!!
Newtons (pimped) Law: Every BOOK continues to be in a state of rest or uniform motion UNLESS and UNTIL  an External or Internal exams COME!!!!!!!!!!!!

Offline X Abdulrahman X

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Re: Physics Help HERE ONLY !!
« Reply #209 on: May 29, 2009, 07:11:44 pm »
hey does anybody have notes to do with magnestism,generators,motors??? my weakness :-\

http://www.physclips.unsw.edu.au/jw/electricmotors.html
Enjoy :)

Thankyouuuuuuuuuuuuuuu!!!! :D :D
have u got any idea how a thermocouple thermometer works?? :P and umm i have a few questions about
Linearity of the thermometers, what does it mean??

a thermocouple consits of 2 wires of 2 different materials joined together, when 1 junction is hotter then the other and electric current flows and produces a reading on a sensitive meter which depends on the temp, difference. they are used in industry, usually measuring -250C to about 1500C

When they talk about me they say I be trippin
What they say about me doesn't make me mad 
I think they hatin cause they see me when I'm rollin
Man I can't help it that they really doin bad  =P

Big cars, Big wheels, Big chains, Big pimpin', Big money, Big Dreams ;-)