Physics, Chemistry and Biology: Post your doubts here!

[Gehad Mohamed]

What should we know about potential divider ? And live earth and neutral wire ?

 

[ZaqZainab]

I get how you find the area of the yellow part, but what do you do after that? I don't understand the last part : area of yellow=1/2*(11.2*x)=1.6 80-x = 7.7
What is x? And why are we finding the area of yellow again when we just found it..? I'm confused, please explain if you can, or someone else, thanks .

x is the difference between the line and 80
x is the height of the yellow triangle
We are not finding the area yellow=1/2*(11.2*x)=1.6 here i am using the formula to find the are of the triangle as we don't know the height the formula is (1/2)* length*height=area we know the length which is (11.2) from the x axis we now the are we found it using another method you have understood so to find x make x the subject i did not mention x because it is in decimals and you should NOT round it so the equation actually is x=area/(o.5*length)
now x is only the difference between the line but we want the length of the line UNDER x we subtract x from 80 and we get the answer
there might be other ways but i found this easy i hope i could have made my self clear

 

[ZaqZainab]

What should we know about potential divider ? And live earth and neutral wire ?

What is a potential divider?Resistors in series, connected across a source of voltage, used to obtain a desired fraction of the total supplied voltage is called potential divider.
how is it done?In case there are 2 resistors and both the resistors have the same value of resistance so provided potential will be divided equally to both of them. But if both resistors have different values then output voltage will depend upon the value of resistance of the resistor across which we are taking the output.
How does the reading increase, decrease? by moving the sliding contact this is the only things you should and yeah an example may be like a Rheostat
What color is Live? Brown
Where is it connected? directly to the generates of the electrical supply
Why will this wire kill you ? It carries a lot of Voltage
What color is neutral wire? Blue
Connects?The Neutral wire returns the electricity to the generator after it has passed through the appliance, to complete the circuit.
Why will it kill you? The Neutral wire is at approximately zero volts but you must NEVER touch this wire either!! If the wiring is faulty it may be carrying the same electricity as the Live wire.<--- in case you end up touching one i will miss you my friend
I hope i helped

 

[Lama AN]

I

Which

Question two ? . I cant figure out what does it talk about ?

 

[birt andrews]

Q1. a) av.speed= (v+u)/2
=15m/s
b) a=(v-u)/t
a=(20-10)/60
a=(1/6)m/s2
distance=ut+1/2at2
=(10*60)+1/2*(1/6)*(60)2
=600+300
=900m

Q2. t=(v-u)/a
t=(1100-600)/10
t=500/10
t=50h

Q3. t=(v-u)/a
t=(0-20)/-5
t=-20/-5
t=4s.

For Question 2) isn't it 50 seconds

 

[Gehad Mohamed]

What is a potential divider?Resistors in series, connected across a source of voltage, used to obtain a desired fraction of the total supplied voltage is called potential divider.
how is it done?In case there are 2 resistors and both the resistors have the same value of resistance so provided potential will be divided equally to both of them. But if both resistors have different values then output voltage will depend upon the value of resistance of the resistor across which we are taking the output.
How does the reading increase, decrease? by moving the sliding contact this is the only things you should and yeah an example may be like a Rheostat
What color is Live? Brown
Where is it connected? directly to the generates of the electrical supply
Why will this wire kill you ? It carries a lot of Voltage
What color is neutral wire? Blue
Connects?The Neutral wire returns the electricity to the generator after it has passed through the appliance, to complete the circuit.
Why will it kill you? The Neutral wire is at approximately zero volts but you must NEVER touch this wire either!! If the wiring is faulty it may be carrying the same electricity as the Live wire.<--- in case you end up touching one i will miss you my friend
I hope i helped

Hhhhhhh xD I will not touch one inshallah , thnxxxxxxxxxxxx alottttttttttt luv u it is helpful thnxxx

 

[Fabienne]

Can someone explain Half Life to me please? n.n

 

[Tina0312]

[CHEMISTRY] what is the difference between covalent bonding and intermolecular force? i know that its the intermolecular force which breaks the bond between elements but what does strong covalent bonding do?

 

[Ahmed Al Hilali]

phy
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s09_qp_3.pdf

5 ( B )

 

[Tina0312]

one more question. why does H2 gas formed instead of reactive metal at cathode during electrolysis? On the xtremepaper revision, it says its because the least reactive elements have more tendencies to be an atom. what does it mean?

 

[zara.f]

biology paper 3 wz very hard -.-

 

[aliraza]

when r u going to post physics paper 33 for a level
2mrw is the pratical

 

[Lightning soul]

Small tip for physics. Write the units and mention the equation used in a calculation

 

[Ahmed Al Hilali]

phy
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s09_qp_3.pdf

5 ( B )


http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s12_qp_31.pdf
11 b and c
why the LDR in gap B and why thermistor in gap A

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_33.pdf
Q10 a

please help me

 

[lujain26697]

definition of analouge and digital as applied to electronic circuits?

 

[ZaqZainab]

phy
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s09_qp_3.pdf

5 ( B )

Half speed 12/2=6
so for 12 it is 7500
for 6 it will be x
6*7500=12x
45000=12x
x=3750 Got it?
OR basically 7500/2 as it is Half <--- easy
Next one 54000 watt is 540000 J
so x Watt is (kinetic energy=0.5*mv^2 i.e 67500=0.5*3750*6^2)J
540000*x=54000*67500
x=67500
fraction of the power output of the wind on the second day as a fraction of first
First day? 54000
Second day? 67500
(second/first)/10 i.e (67500/54000)/10= 0.125
I hope you got it

 

[ZaqZainab]

phy
http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s09_qp_3.pdf

5 ( B )


http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s12_qp_31.pdf
11 b and c
why the LDR in gap B and why thermistor in gap A

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_w10_qp_33.pdf
Q10 a

please help me

5B Answered
11 b Because it is NPN transistor the current flow is from emitter to base and here you DON'T need a thermistor (This is for temperatures and here we don't have to note the temperature) Your question why don't we keep Variable resistor at b and LDR at A this has a lot to explain but lemme give it a go so when the light intensity decreases(becomes dark) the resistance increases for LDR and now when Resistance increases Voltage increases and we need a higher share of voltage at B not at A because we need the PD across the Base to e larger enough for the base current to switch on the collector-emitter current as when the large current flows from the collector to emitter the bulb will light and at A is has Less share of resistance from the power supply.
c- Themistor Hot and then Resistance decrease ad voltage decrease so this has to be placed at A this time to switch on the circuit Large voltage at B and low at A so that all about this
I really can explain you 10 a wordy

 

[Faaiz Haque]

x is the difference between the line and 80
x is the height of the yellow triangle
We are not finding the area yellow=1/2*(11.2*x)=1.6 here i am using the formula to find the are of the triangle as we don't know the height the formula is (1/2)* length*height=area we know the length which is (11.2) from the x axis we now the are we found it using another method you have understood so to find x make x the subject i did not mention x because it is in decimals and you should NOT round it so the equation actually is x=area/(o.5*length)
now x is only the difference between the line but we want the length of the line UNDER x we subtract x from 80 and we get the answer
there might be other ways but i found this easy i hope i could have made my self clear

I don't understand , sorry, thanks for help though

 

[Faaiz Haque]

Need help question 1 A iii
http://papers.xtremepapers.com/CIE/Cambridge%20IGCSE/Physics%20(0625)/0625_w10_qp_33.pdf
Thanks

 

[AlphaWolf]

Hello everyone, I have an urgent question. So I saw similar questions in many past papers now. How do you solves these kinds of questions, step-by-step:

Q3(a) http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Physics (0625)/0625_s03_qp_3.pdf