Biology; Chemistry; Physics: Post your doubts here!

[Afnan Hafiz]

Advantages of underground transmission?

Underground cables take up less right-of-way than overhead lines, have lower visibility, and are less affected by bad weather. Underground lines are strictly limited by their thermal capacity, which permits less overload or re-rating than overhead lines. Long underground AC cables have significant capacitance, which may reduce their ability to provide useful power to loads beyond 50 miles. Long underground DC cables have no such issue and can run for thousands of miles.

 

[Dark Destination]

- State and explain the use of important practical methods of thermal insulation for buildings.

- Why is iron used for magnetic screening? And what magnetic screening?

- Magnetic relay? Reed switch? Reed relay? What are they?

- Advantages of arranging cells in parallal?

- Why are switches and fuses wired to live wire?

 

[muhammadali233]

does brightness depend on voltage or current...

on resistor if it is an LDR(light dependent resistor)

 

[muhammadali233]

i dont think it is in our syllabus. or is it?

it is

 

[Laibaaa]

it is

What is Light emitting diode? I haven't studied it, couldn't find it in the book

 

[Dark Destination]

What is Light emitting diode? I haven't studied it, couldn't find it in the book

A diode that emits light. It has p-type and n-type junctions, and when its in forward bias, the current that flows through it causes the electrons to move from high energy level to low energy level. This emits light.

Circuit symbol:

 

[muhammadali233]

What is Light emitting diode? I haven't studied it, couldn't find it in the book

it is an diode which emits light when current passes through it,simple
just as diode it lets 1 direction of current to flow through it
and yes the question can of LED's and tell them it is efficient then filament lamp,takes very less energy and emits less heat/internal energy so less is wasted

 

[Laibaaa]

it is an diode which emits light when current passes through it,simple
just as diode it lets 1 direction of current to flow through it
and yes the question can of LED's and tell them it is efficient then filament lamp,takes very less energy and emits less heat/internal energy so less is wasted

A diode that emits light. It has p-type and n-type junctions, and when its in forward bias, the current that flows through it causes the electrons to move from high energy level to low energy level. This emits light.

Circuit symbol:

View attachment 43140

Thank you both so much , got it! ^.^
aaah, 2 hours. Best of luck you guys. Please remember me in your prayers, I will too. Take care

 

[muhammadali233]

Thank you both so much , got it! ^.^
aaah, 2 hours. Best of luck you guys. Please remember me in your prayers, I will too. Take care

3hrs to precise

 

[Faizan Muhammmad]

And you've stolen exploded's avy.

no its really mine

 

[Faizan Muhammmad]

Khud hi ro raha tha mera bhai. Kaha koe achi si lgo to achi si lga di.
Ab btao ye lenz law ko follow nahi kr raha?

laga lee?
bohut sakun milgaya na?

 

[Faizan Muhammmad]

Alrighty people.

Am I the only one who did the third part of Section B?

And how do you reduce the frequency of the rope?

na me too
move it slower

did you subtract 50 in first quest. s last part?

 

[Abdul Hanan]

what were the questions and answer of first 2 parts of lenses question!!!
pls tell i think i only got that question wrong :/

 

[asadalam]

what were the questions and answer of first 2 parts of lenses question!!!
pls tell i think i only got that question wrong :/

Any value less than 2.8.
Any value higher than double of 2.8
I didnt get the 2nd one right :/

 

[DaniyalK]

Any value less than 2.8.
Any value higher than double of 2.8
I didnt get the 2nd one right :/

I think the first one can be between 2.8 and 5.6 because image is diminished when it is between f and 2f.

 

[Abdul Hanan]

Any value less than 2.8.
Any value higher than double of 2.8
I didnt get the 2nd one right :/

so if i wrote 2 cm for part A and 7cm for part b is it correct?

 

[asadalam]

so if i wrote 2 cm for part A and 7cm for part b is it correct?

Yes

 

[M.Omar]

Now tht,s wht I call a paper(only P2)
how did it go for u all.

What abt tht piston question Wht was the value of F.did we have to subtact the value

 

[Abdul Hanan]

Now tht,s wht I call a paper(only P2)
how did it go for u all.

What abt tht piston question Wht was the value of F.did we have to subtact the value

yea answer was 116 something

 

[M.Omar]

yea answer was 116 something

117for me ...I was confused when it was of 1 mark?
Wht abtr tht efficiency question wht do u reckon wud be th 2 marks/2 points?