Biology; Chemistry; Physics: Post your doubts here!

[bogus]

its C, how can it be D ?

oh yeah my bad i wrote the wrong option though i was thinking c

 

[bogus]

why is it D or C? thts wht i dont understand....shudnt acceleration increase as velocity increases??

air resistance decreases acceleration

 

[daredevil]

how does a capacitor and a transistor work?/

A capacitor stores charges by charging itself and dischrging. e.g. a fan. the fan slowly picks up speed tht is because of the capacitor in it and same goes for stopping the fan; it takes time. -| |- this is the symbol for a capacitor. it is important part of the mcq paper (the symbol). a capacitor is also used in a time-delay circuit where we add a resistor to control the amount of time taken for a capacitor to charge and discharge. hope this helps.
i don't know about the transistor and i'm not even sure if its includded in the syllabus

 

[Fallen316]

RANDOM PHYSICS NOTES!!​

​

Ways to increase emf in solenoid​

1.Use a stronger magnet.
2.Increase the speed of moving the magnets.
3.Increase the number of turns on the coil.

Ways to increase emf in a.c. generator
1.Decrease distance between the magnet and coil.
2.Use a stronger magnet.
3.Increase speed of moving the magnets
4.Increase number of turns in the coil.

When a water wave moves from deep to shallow
1.Wavelength become shorter
2.Frequency remains the same
3.Speed becomes slower

Factors that affect speed of sound
1.Temperature – The higher, the faster
2.Medium – Solid is faster than liquid, which is faster than gas
3.Humidity – More humid faster than less humid

Characteristics of Image formed on plane mirror
1.Same size
2.Laterally inverted
3.Image is virtual
4.Distance of object from mirror is = distance of image from mirror
5.Same colour
6.Inverted front to back

Precautions when handling radioactive substances
1.Radioactive substances should not be touched.
2.Do not point their rays at any person.
3.Wear a photosensitive badge to check whether a person is exposed to an overdose of radiation.

Operation of Transformer
1.Alternating current is supplied to primary coil.
2.Alternating current causes iron core to magnetise and magnetic field to change.
3.Magnetic fields follow iron core and link to secondary coil.
4.Hence emf is induced in secondary coil by electromagnetic induction.

Operation of AC Generator
1.Turn the wire.
2.The wire cuts through the magnetic field as it turns.
3.This produces an induced emf.
4.Because of the load, an induced current is produced.

Process of creating Convection current
1.The bottom layer is heated, the molecules move faster.
2.The density decreases and hot water rises.
3.Cooler and denser water above sinks down and takes its place.
4.Convection current is due to a change in density.

Difference between evaporation & boiling:
EVAPORATION/BOILING
1.Takes place on the surface/Occurs throughout the liquid
2.Temperature may change in this process/Temperature remains constant
3.Takes place at any temperature/Takes place at a constant temp.
4.Artificial heating is not required/Artificial heating is required.
5.Slow Process/Fast Process.

CLICK LIKE IF IT HELPED

 

[luckywang]

got notes about CRO, semiconductor, potential divider,bistable&astable circuit? im not sure about the function and the structure like why that thing put at there and it put there for what and something like that...
and i wanna ask:
1)convection can only occur in liquid and gases?
2)how heat energy transfer into and out of a house?
3)we have to memorise the colour of resistor? or the information will be given?

 

[Fallen316]

got notes about CRO, semiconductor, potential divider,bistable&astable circuit? im not sure about the function and the structure like why that thing put at there and it put there for what and something like that...
and i wanna ask:
1)convection can only occur in liquid and gases?
2)how heat energy transfer into and out of a house?
3)we have to memorise the colour of resistor? or the information will be given?

ill see for the notes.
1)yes Only in liquid and gases
2)by conduction,convection and radiation ( all 3 )
3)better to memorize. its easy just remember the first 2 and the last 2
first 2 are black and brown , then the colors of rainbow ( R O Y G B V ) exclude indigo , and the last 2 grey and white
this is the order and the numbering is simple, you know that

 

[fatima360]

how do we do the last part in last question??the mass of sodium nitrate crystallised??

 

[Fallen316]

how do we do the last part in last question??the mass of sodium nitrate crystallised??

they had given us the temperature of the solution i.e 50degrees.
you had to take the reading of solubility from the graph at 50degrees temperature. ( mine was 80 )
the mass was original sodium nitrate was given --> 150g
subtract 80 from 150 . Ans --> 70

 

[fatima360]

is bipolar transistor,processor,output device,nd feedback important??

 

[Fallen316]

is bipolar transistor,processor,output device,nd feedback important??

nupsey.

 

[Mayedah]

got notes about CRO, semiconductor, potential divider,bistable&astable circuit? im not sure about the function and the structure like why that thing put at there and it put there for what and something like that...
and i wanna ask:
1)convection can only occur in liquid and gases?
2)how heat energy transfer into and out of a house?
3)we have to memorise the colour of resistor? or the information will be given?

The colours of resistors are given always but still u can ldl them !

 

[fatima360]

they had given us the temperature of the solution i.e 50degrees.
you had to take the reading of solubility from the graph at 50degrees temperature. ( mine was 80 )
the mass was original sodium nitrate was given --> 150g
subtract 80 from 150 . Ans --> 70

why do u subtract it???
i took the readingfrom graph (mine was 84)
nd then put it in the fromula
solubility(which was 84)=mass/volume *100
nd answer was 84

 

[Fallen316]

why do u subtract it???
i took the readingfrom graph (mine was 84)
nd then put it in the fromula
solubility(which was 84)=mass/volume *100
nd answer was 84

at 50degrees we know that the solubility is 80 (in 100cm3 of water) , right ?
the mass they had given (150) was also in solution with 100cm3 of water.
when you put it in the formula you get 84g of mass which is soluble , right ?
the question does not end here.
then you subtract the soluble from total and get the pure sample.
I hope you get it

 

[fatima360]

at 50degrees we know that the solubility is 80 (in 100cm3 of water) , right ?
the mass they had given (150) was also in solution with 100cm3 of water.
when you put it in the formula you get 84g of mass which is soluble , right ?
the question does not end here.
then you subtract the soluble from total and get the pure sample.
I hope you get it

thankss...there goes my 2 marks

 

[luckywang]

2)by conduction,convection and radiation ( all 3 )

only describing this three? nothing about the structure of house like double glazing window, roof and wall? just the process?

 

[Fallen316]

only describing this three? nothing about the structure of house like double glazing window, roof and wall? just the process?

if they ahve provided details of the house then you also write like heat loss by roof is through radiation and then describe it.

 

[luckywang]

thankss...there goes my 2 marks

dont be sad... im not even have enough time to think about it... i waste too much time on the graph and i not feeling well today... waste too much time to understand the question... hope no calculation mistake....

 

[luckywang]

if they ahve provided details of the house then you also write like heat loss by roof is through radiation and then describe it.

how about preventing heat loss?

 

[fatima360]

can anybody tell me an experiment to find critical angle(using an appropriate appratus)??

 

[daredevil]

how about preventing heat loss?

u can't prevent heat loss u can just minimise it. and u an minimize it using the double glazed windows, air trapped in the roof; shiny roof and whatever the hell else u can do!!