Biology; Chemistry; Physics: Post your doubts here!

[Vogue]

explain the choice of material for , and use of, magnetic screening

iron is using for magnetic shielding
it does not allow any magnetic field to reach the component enclosed in its ring

 

[Vogue]

1)describe the action of a bipolar npn transistor as an electrically operated switch explain its use in switching circuits
2) describe the use of a bistable circuit
3) discuss the fact that bistable circuit exhibit the property of memory
4) describe the use of an astable circuit (pulse generator)
5) describe how the frequency of an astable circuit is related to the values of the resistive and capacitative components

these r optional things that never come. At least i never saw them in any recent paper. Have u?

 

[Vogue]

explain using nuclide notation how one element may have a number of isotopes

I am sure you know it. Just lyk in periodic table, the symbol of an element is writen and on its upper left side, its atomic mass is riten nd lower left side proton number is writen. that is called nuclide notation.
so in isotopes, u just hv to change the atomic mass number

 

[Vogue]

please would anyone EXPLAIN how the following components actually work in stated applications

1) radio waves__radio and television communications
2) microwaves__satellite television and telephone
3) infra red ___household electrical appliances , television controllers and intruder alarms
4) light ___ optical fibres in medical uses and telephone
5) ultra violet ___ sunbeds , fluorescent tubes and sterilisation
6) X-rays ___hospital use and engineering applications
7) gamma rays and their use in medical treatment

is this thing in syllabus? or r u asking for sake of info?

 

[fatikhalid]

these r optional things that never come. At least i never saw them in any recent paper. Have u?

no i ahven't seen them bt they r a part of syllabus!

 

[fatikhalid]

is this thing in syllabus? or r u asking for sake of info?

this is in syllabus...

 

[fatikhalid]

I am sure you know it. Just lyk in periodic table, the symbol of an element is writen and on its upper left side, its atomic mass is riten nd lower left side proton number is writen. that is called nuclide notation.
so in isotopes, u just hv to change the atomic mass number

thankyouuuuuu.......::::::::::::))

 

[fatikhalid]

iron is using for magnetic shielding
it does not allow any magnetic field to reach the component enclosed in its ring

i wish i could press the like button twice!!.. thankyou!

 

[Vogue]

this is in syllabus...

ok then i think the answer to such question will b very simple(i saw it in classified i gues) . yes so it will say that all waves move wid speed of lyt. they r transverse so their molecules vibrate and move perpendicular to the vibration. and as far as satellite and phone r concerned then u can ryt that these waves go to the booster and regain their signals.

 

[fatikhalid]

ok then i think the answer to such question will b very simple(i saw it in classified i gues) . yes so it will say that all waves move wid speed of lyt. they r transverse so their molecules vibrate and move perpendicular to the vibration. and as far as satellite and phone r concerned then u can ryt that these waves go to the booster and regain their signals.

umm...k..thnx!..

 

[GlitteringLights]

0610 w11 qp 63

ques # :
1 ) (c)(i) can you please explain how the answer is derived? thank you

 

[ashiqbal]

1)describe the action of a bipolar npn transistor as an electrically operated switch explain its use in switching circuits
2) describe the use of a bistable circuit
3) discuss the fact that bistable circuit exhibit the property of memory
4) describe the use of an astable circuit (pulse generator)
5) describe how the frequency of an astable circuit is related to the values of the resistive and capacitative components

these are circuits containing transistors and/or capacitors

astable circuits switch continually from one state to other, eg traffic lights, as they contain two capacitors
bistable circuits are switched on and off manually.

these topics are optional, but unfortunately, some of these topics can come in mcqs, so you should have just a little bit knowhow!

 

[robinhoodmustafa]

http://www.xtremepapers.com/community/threads/olevel-notes-center.11138/
Visit Here and Get Notes on every subject ... Also give me ur thoughts and likes

 

[fatikhalid]

than

these are circuits containing transistors and/or capacitors

astable circuits switch continually from one state to other, eg traffic lights, as they contain two capacitors
bistable circuits are switched on and off manually.

these topics are optional, but unfortunately, some of these topics can come in mcqs, so you should have just a little bit knowhow!

thankyou soo much!!!...)

 

[ashiqbal]

thankyou soo much!!!...)

you are welcome

 

[snowbrood]

why is fuse connected to live wire?? what would happen if it was connected to neutral wire please explain

 

[Raikko]

COuld any one tell me how to erase the part "Extreme papers" in each pastpaper question.....?

 

[khizer shahab]

why is fuse connected to live wire?? what would happen if it was connected to neutral wire please explain

it is done bcuz when a fuse is blown . the appliance has no contact with live wire therefore it could be touched unharmed while if fuse is placed at neutral wire then touching the appliance would be dangerous bcuz charges would be accumulated on the appliances all over as person would touch, electricity would get the path and travel form the body.!!!

like if u find it useful

 

[scouserlfc]

0610 w11 qp 63

ques # :
1 ) (c)(i) can you please explain how the answer is derived? thank you

Actually isnt this IGCSE or some other board and not O levels,but i think we can solve it 1

 

[GlitteringLights]

Actually isnt this IGCSE or some other board and not O levels,but i think we can solve it 1

whoopsies! yes it is :$ haha thanks i think i shall search for the IG thread but if you can solve this, that's great ! :$