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[Vin]

2010 luv ur signature !! XD

[Fastal]

guys is
P=hdg only applicable to liquids
cuz i used that formula for air pressure in a past paper

anyone?

[Vin]

anyone?

which paper ?? depends on the context ..

[Helium]

this is about springs


It says that force is proportiional to extension

F IS FORCE
K  IS SPRING CONSTANT X IS EXTENSION

The constant is defined as how much force is need to stretch the spring by 1m adn the unit is N/m or N/mm or N/cm

K = F/x

a spring with a large spring constant  is hard to stretch ( needs alot of force ) while one with small spring constant need less

Thanks that was a very good explanation

[guMnam]

@ kimo jesus......are u a teacher or wat.. nice stuff gud work:D

[WARRIOR]

@ kimo jesus......are u a teacher or wat.. nice stuff gud work:D

lol no im doing the ig with you guys :p

just a good skool i guess and some stuff i plainly taken off the book 

[WARRIOR]

help

October november 2004

Describe the action of a tranistor?

can you say   When voltage accross the base and emitter iis large enough the transistor switches on and aloows a large current to pass

mark scheme asnwers : http://www.freeexampapers.us/IGCSE/Physics/CIE/2004%20Nov/0625_w04_ms_3.pdf   ( question 10 2)

i dont understand any ^

[Vin]

10 a) a transistor can be used as a switch

b) the base current of the transistor can be varied, works only when Voltage in base is greater than 0.6 V , small change in base current can produce a large change in collector or emitter current

[WARRIOR]

10 a) a transistor can be used as a switch

b) the base current of the transistor can be varied, works only when Voltage in base is greater than 0.6 V , small change in base current can produce a large change in collector or emitter current

ok but what do u mean by

[Vin]

there are two current paths through a transistor .. base emitter and collector emitter which is via base ..A voltage or current applied to the  terminals changes the current flowing through another pair of terminals.Because the output power can be much more than the controlling input power, the transistor provides amplification of a signal.

The essential usefulness of a transistor comes from its ability to use a small signal applied between one pair of its terminals to control a much larger signal at another pair of terminals. This property is called gain. A transistor can control its output in proportion to the input signal, that is, can act as an amplifier.

[WARRIOR]

there are two current paths through a transistor .. base emitter and collector emitter which is via base ..A voltage or current applied to the  terminals changes the current flowing through another pair of terminals.Because the output power can be much more than the controlling input power, the transistor provides amplification of a signal.

The essential usefulness of a transistor comes from its ability to use a small signal applied between one pair of its terminals to control a much larger signal at another pair of terminals. This property is called gain. A transistor can control its output in proportion to the input signal, that is, can act as an amplifier.

i see thanks !

[Vin]

just a property .. u jus hav to know them .. nothing to understand i suppose ..

[Ghost Of Highbury]

u have to understand them..very important..

check june 07 Q10 b)...abt transistors..

a guy called "cooldude" had answered it beautifully ...if u want i can get that explanation for u..

[Vin]

yea please .. our teacher never taught us properly .. :\

thanks ..

[Ghost Of Highbury]

ans10b)
see if we want to change the temperature at which the lamp switches on, we have to change the value of resistance R1. if we increase the value of the resistance then more voltage will flow through the transistor and if we decrease the voltage then less voltage will flow through the transistor. therefore if we assume that the amount of heat falling on the thermistor is constant then when we increase or decrease the value of R1 so will the value of the voltage passing through the tranistor will change. so if we want to make the lamp switch on at a different temperature we change the value of R1 because if the heat is falling on the thermistor and thus its resistance decreasing then if the base voltage is enough to switch on the transistor it will light however decreasing the value of the resistor R1 will cause the voltage flowing through the transistor to be too less to switch it on (this is if we want to make the temperature at which the lamp lights more; just explain the opposite thing if u want the temperature at which the transistor lights lower than it is and also u dnt need to expalin all this, ive done this to help u understand it and if u want a shortened version ill be happy to help). therefore in short the temperature at which the lamp lights can be changed by changing the value of R1. (the lamp lights when the base voltage becomes enough for the lamp to switch on)