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Edexcel PHYSICS Doubts

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The Golden Girl =D:

--- Quote from: ang3l on June 01, 2011, 01:34:23 pm ---Question in attachment..Can anyone draw the circuit

The ms says this:

See 2 resistors in parallel with supply (1)
Supply across ends of variable resistor (10 ?) (1)
Fixed resistor across one end and slider (consequent mark) (1)

Thanks

--- End quote ---

I have it somewhere so I'll get back to you in a few minutes iA.

EDIT: Attached.

Malak:
GG...Ur awesome :D

I have few more doubts  ::)

In first Q..Why is the answer D?  ???

The last two Qs are of the same sort, just need a basic explanation.

Thanks Alot :)

High-R:
6B how many pastpapers r u people doing?

or where r u prctising from??

The Golden Girl =D:

--- Quote from: ang3l on June 01, 2011, 09:37:54 pm ---GG...Ur awesome :D

I have few more doubts  ::)

In first Q..Why is the answer D?  ???

The last two Qs are of the same sort, just need a basic explanation.

Thanks Alot :)


--- End quote ---

It'll take me time to type all my answers so I hope you have patience.

EDIT : I don't get the first one and the last one :S


my answer for the second Question is as follows ;

Lamp

As the temperature increases , the atoms vibrate violently .
flow of charge is blocked by the vibrating atoms.
 the flow of charge decreases and ,since the flow of charges is directly proportional to the current , the current decreases hence the resistance increases

Thermistor

As temperature increases , the electrons gain Kinetic energy  and they hit the lattice atoms and  the flow of charges increases , and since the flow of charges is directly proportional to the current , the current increases and hence the resistance decreases

EDIT :
for the First Question

Thanks to Master_Key ;

Divide the current into two parts. Like if 3 A Max.

then 1A for R

and 2A for R1+R2.

P = I2R

For P of R
P = 12R

For P of R1+R2
P = 22R1 or R2

P in R1 and R2 are same

Ratio is 1 : 4.

or  Conside R and R1+R2 in parallel.

Take V as a fixed V. In parallel circuits, V is always same.
P = V2/R

For P of R

P = V2/R

For P of R1+R2

P = V2/(R1+R2)

and find the ratio.

EDIT again :P


--- Quote from: Master_Key on June 02, 2011, 08:54:21 am ---Question 3.
I = nAqv where
 I = current
 n = charge carrier density
 q = charge of an electron
 v = drift speed

Increase in temperature decreases the resistance of Thermistor.
The increase in temperature causes an increase in drift velocity, so current increases if voltage is to remain same. That explains I against V graphs that defy Ohm's law (which would predict a straight line) for thermistor.

hope i helped.

MORE HELP FOR PHYSICS FROM HERE.

resources.r9paul.org/ASA2/Physics/AS_RevisionBook.pdf

--- End quote ---

Vampire-Love4ever:

--- Quote from: High-R on June 02, 2011, 06:49:12 am ---6B how many pastpapers r u people doing?

or where r u prctising from??

--- End quote ---

Sample paper, June 2010 and Jan 2011 papers.

Revise notes.

https://studentforums.biz/reference-material-83/edexcel-chemistry-and-physics-unit-6b/

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