Physics, Chemistry and Biology: Post your doubts here!

OneOfAKind

OneOfAKind

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Please help me out here, I am attaching 2 photos here please find them.
Here is my question, first pic says that if Current increases the Resistance increases because Current increases the temperature and it in turn increases the Resistance
but in the second picture it says that if the Current increases the Resistance always decreases ... this got me really confused! please someone help me out
 

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Awesome12

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Lola_sweet said:
Resistance can be thought of as an opposing force that would cause a decrease in current. So as temperature increases, the resistance decreases. An increase in temperature will allow more molecules in the substance/ conductor to become free and carry charges. Since there are more current carrying molecules produced, then resistance decrases.

i guess the info u read had made a mistake
Click to expand...
Temperature is directly proportional to resistance. If you use a thin wire for your ac, it will burn out, because a large current flows, and since the wire is thin, more resistance occurs, causing it to burn
 
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OneOfAKind said:
Please help me out here, I am attaching 2 photos here please find them.
Here is my question, first pic says that if Current increases the Resistance increases because Current increases the temperature and it in turn increases the Resistance
but in the second picture it says that if the Current increases the Resistance always decreases ... this got me really confused! please someone help me out
Click to expand...
The second one seems to be wrong.
Voltage is not constant. In a series circuit, it is divided. In a parallel circuit, it is constant
 
OneOfAKind

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Awesome12 said:
The second one seems to be wrong.
Voltage is not constant. In a series circuit, it is divided. In a parallel circuit, it is constant
Click to expand...
No, the statement means that what ever the condition of of the current or resistance shall be (low/high) the voltage delivered by the battery will be constant, so now sliding that matter away can you solve my doubt? ..
 
Lola_sweet

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exploded diper said:
hey! winter
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if its paper 11 of winter 2009 mcq 3 answer is D because the salt will be dissolve in water where as the sand wont thus you can remove sand by filter. and then when you evaporate the salt and water solution the water will evaporate of leaving the salt behind.
if its paper 12 of winter 2009 mcq 3 answer is C because after you mix the metal and acid you must filter to remove excess.
 
exploded diper

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Lola_sweet said:
Resistance can be thought of as an opposing force that would cause a decrease in current. So as temperature increases, the resistance decreases. An increase in temperature will allow more molecules in the substance/ conductor to become free and carry charges. Since there are more current carrying molecules produced, then resistance decrases.

i guess the info u read had made a mistake
Click to expand...
in the book it says tht since the resistance of the tungsten is high so it heats up more ( in electric kettles)
and then in tranmission wires you increase the voltage and hence the resistence so so less heat is lost.....explain
 
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Phoenix Blood said:
Can you explain 4, (b) ?
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We are calculating the gravitational potential energy of the athlete. The height of the body is taken in to account with its centre of mass( in this case).
When we move a body up a hill, its centre of mass travels with it. In this case, the centre of mass has not risen by 2.0 meters. It has risen, but has not risen that significantly and is still less than 2.0 meters
 
exploded diper

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Awesome12 said:
We are calculating the gravitational potential energy of the athlete. The height of the body is taken in to account with its centre of mass( in this case).
When we move a body up a hill, its centre of mass travels with it. In this case, the centre of mass has not risen by 2.0 meters. It has risen, but has not risen that significantly and is still less than 2.0 meters
Click to expand...
(adding).....since he is bendng so his cntre of mass is lowered
 
OneOfAKind

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Lola_sweet said:
Resistance can be thought of as an opposing force that would cause a decrease in current. So as temperature increases, the resistance decreases. An increase in temperature will allow more molecules in the substance/ conductor to become free and carry charges. Since there are more current carrying molecules produced, then resistance decrases.

i guess the info u read had made a mistake
Click to expand...
You're really confusing me! till yet I was pretty sure if temprature increases resistance increases!
 
3abder7man

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center of mass i
Awesome12 said:
We are calculating the gravitational potential energy of the athlete. The height of the body is taken in to account with its centre of mass( in this case).
When we move a body up a hill, its centre of mass travels with it. In this case, the centre of mass has not risen by 2.0 meters. It has risen, but has not risen that significantly and is still less than 2.0 meters
Click to expand...
Just a little correction, center of mass is the one always used, not just in this case.
 
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