Physics, Chemistry and Biology: Post your doubts here!

[princess sofia]

The LDR's resistance becomes high, making the voltage across the LDR bigger, which causes the transistor to switch on the lamp.

bt voltage is directly propotional to resisitence across a conductor
#CONFUSED

 

[rida.12.!!]

state what is meant by an electromotive force of 12 V

 

[eureka!]

Phoenix Blood Here you go...
A thin aluminum foil is placed some distance in front of a radioactive source emitting alpha particles, in vacuum. Using a counter, the number of alpha particles can be detected. Most pass right through the foil and straight ahead. Few are deflected to one side, and about 1 in 8000 are bounced back.
Now since alpha particles are +vely charged, they are repelled when confronted with a positive charge and will deflect in the presence of unlike charges. So this experiment proves that the protons are situated in a dense nucleus that is only a very tiny fraction of the whole atom, and that most of the atom is empty space. (That's why most alpha particles are unaffected.)

 

[R_Ma7mooD]

thx

ur welcome

bt voltage is directly propotional to resisitence across a conductor
#CONFUSED

In these types of circuits, it operates slightly different, IN the dark the LDR will have a high resistance and so the voltage at the junction will be high, making the transistor turn on, and so is the light.
But when the resistance is low the voltage at the junction will be low causing the transistor to turn off.

 

[Phoenix Blood]

eureka! now see- Voltage is same in lamps X and Y, right? So when Y is removed, why is it making Z dimmer?

 

[eureka!]

Phoenix Blood
Alternating current in primary coil produces changing magnetic field in soft iron core. This induces an a.c. in the secondary coil.
If step-up, no. of turns in 2ndary coil greater; output voltage greater. And vice-versa.

 

[R_Ma7mooD]

state what is meant by an electromotive force of 12 V

That the voltage across the terminals of a power source of electrical energy is 12V(like a battery). when fully charged.

 

[princess sofia]

state what is meant by an electromotive force of 12 V

It means dat an energy of 12 J is required to move charge around a complete circuit in one second

 

[awesomaholic101]

Its 2014 paper

hw cum?? ur messing with us rite?

 

[princess sofia]

hw cum?? ur messing with us rite?

forget it he is really meesing around to get sme cheap attention

 

[awesomaholic101]

forget it he is really meesing around to get sme cheap attention

lol... God nly knos!!

 

[Awesome12]

hw cum?? ur messing with us rite?

forget it he is really meesing around to get sme cheap attention

No he is not. That is a serious 2014 paper. All of the IGCSE papers have been leaked in Kuwait, and multiple variants have been changed. You can see in the background; the paper seal, the folder in which the papers come. Also the paper quality is exactly the same as the paper that comes in the exam. This my friends, is a real 2014 paper that, that person has in his possession

 

[awesomaholic101]

Guys can u help me with:

One man walks along a 10 meters slope at a height of 3 meters. And another man walks straight forward for 8 meters then climbs a ladder at a height of 3 meters.
Which man does more work and why?

it shud b the second person bcoz he is walking a distance of 11m (8+3) ... while the first one is ly goin 10m .... nd work done = force x distance

 

[eureka!]

No he is not. That is a serious 2014 paper. All of the IGCSE papers have been leaked in Kuwait, and multiple variants have been changed. You can see in the background; the paper seal, the folder in which the papers come. Also the paper quality is exactly the same as the paper that comes in the exam. This my friends, is a real 2014 paper that, that person has in his possession

https://www.xtremepapers.com/community/attachments/img-20140516-wa0011-jpg.42919/
Zoom in on the date below.
SalmanPakRocks Nibz XPFMember CaptainDanger badrobot14 AnGeL.Of.DaRkNeSs

 

[R_Ma7mooD]

it shud b the second person bcoz he is walking a distance of 11m (8+3) ... while the first one is ly goin 10m .... nd work done = force x distance

hmmm but don't the person climbing the ladder use more force than the one walking along the slope?

 

[awesomaholic101]

hmmm but don't the person climbing the ladder use more force than the one walking along the slope?

yea .. the second person is the one whoz whos climbing the ladder rite??
nd frce is not our concern here coz its not given in the question

 

[awesomaholic101]

No he is not. That is a serious 2014 paper. All of the IGCSE papers have been leaked in Kuwait, and multiple variants have been changed. You can see in the background; the paper seal, the folder in which the papers come. Also the paper quality is exactly the same as the paper that comes in the exam. This my friends, is a real 2014 paper that, that person has in his possession

so u mean that guy actually has the whole paper with him??

 

[R_Ma7mooD]

yea .. the second person is the one whoz whos climbing the ladder rite??
nd frce is not our concern here coz its not given in the question

yeah, but when my teacher marked the paper she marked is as wrong. :/ I was confused, asked her she told me that the first man traveled more distance while going slightly up, so the first guy does more work.

But still I'm not convinced with my teacher's explanation, and feeling lost somehow in this lesson.

 

[awesomaholic101]

yeah, but when my teacher marked the paper she marked is as wrong. :/ I was confused, asked her she told me that the first man traveled more distance while going slightly up, so the first guy does more work.

But still I'm not convinced with my teacher's explanation, and feeling lost somehow in this lesson.

isnt the distance for the first guy clearly given as 10m ??

 

[R_Ma7mooD]

isnt the distance for the first guy clearly given as 10m ??

since I dont have the paper, but the numbers are quite in this form, yeah it was around 10-9.