Biology; Chemistry; Physics: Post your doubts here!

multixamza01

multixamza01

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khanrocks20 said:
can u please answer this:
explain the process of transpiration
Click to expand...

The water is transported by the xylem upto the leaves.
The leaves store the water in mesophyl cells. The mesophyl cells , have a moist layer on their surfaces. This moist layer makes the air spaces concentrated with water vapour. When the air spaces become more concentrated then the atmosphere outside the leave , a concentration gradient builds. The stomata open and the water vapours diffuse out of the leaf.
 
daredevil

daredevil

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can u please give some notes on germination, vegetative propogation, malaria and coordination.
 
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nightmaressana

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guys can someone please explain to me what a npn transistor and a capacitor is? what is a bistable circuit and its use? and what is an astable circuit?
we have finished the syllabus but we havent done it, teachers say that it doesnt come often and so they dont teach it, but just to be on the safe side, can somebody please explain to me these? thank you!
 
SalmanPakRocks

SalmanPakRocks

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nightmaressana said:
guys can someone please explain to me what a npn transistor and a capacitor is? what is a bistable circuit and its use? and what is an astable circuit?
we have finished the syllabus but we havent done it, teachers say that it doesnt come often and so they dont teach it, but just to be on the safe side, can somebody please explain to me these? thank you!
Click to expand...
Transistor.
It is a semi-conductor device with 3 terminals. It acts as a gate and only allow the current which is more than 0.6 A to pass through it. A variable resistor may be attached along with the trasnsistor as it is very sensitive to current and high voltage current has destroy it.
Capacitor.
It is a device used to store the electrical charge. It consist of two plates, one for storing positive charge and another for negitive. It can only be charged from D.C CURRENT. After doing so it can be discharged by connecting with any other electrical appliance, such as resistor, bulb etc.
 
multixamza01

multixamza01

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Here are the Physics ''Quick Revision Notes'' that were requested earlier.
 

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Tharindu

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Can anybody tell me what is the advantage of getting A* compared to getting As and Bs...what i also mean is that o level doesnt count much
 
Iridescent

Iridescent

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Tharindu said:
Can anybody tell me what is the advantage of getting A* compared to getting As and Bs...what i also mean is that o level doesnt count much
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The more the marks u get the better it is. As simple as that!
Anyway, you get scholarships if you get A*s n its considered gud. Simple!
 
mintchocolate4567

mintchocolate4567

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how to check for a zero error in a)voltmeter b)ammeter????
P.S is that even included in our syllabus?? -_-

and als0 if anyone can answer the following questions:

Q9: WHY THE TEMPERATURE 20OC IS MARKED ON THE MEASURING CYLINDER?

Q30: BEFORE CLOSSING THE SWITHCH, WHY IS THE RHOSTATE ADJUSTED TO ITS MAXIMUM VALUE?

Q32: WHAT IS THE ADVANTAGE OF USING SMALLER COMPASS?

Q59: WHAT IS MEANT BY
A)RESPONSIVENESS
B)LINEARITY
C)SENSITIVITY OF A THERMOMETER?

Q69: WHY THE CROSS-SECTION OF THE STEM OF THERMOMETER IS PEAR-SHAPED?

Q19: WHY THE FULCRUM SHOULD HAVE SHARP EDGE?

:)
 
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