CBSE > Class 12 > Physics | CBSE Board | Homework Help

But yeh to distinction h naa on the basis of band theory i want to understand the band theory in which vo interatomic spacing n crystal lattice spacing is there.

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Meghna Sharma 6 years ago

Arre yr yeh to smjh aa gya

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Shruti Jha 6 years ago

Seeeeeeeeeeeee In some solids the conduction band and valence band are overlapped. So energy band gap is 0. Due to this electron can move freely in conduction band. Hence conduction occur. And these solids are called CONDUCTOR or METALS. In some solids the energy band gap is more than 3eV due to which no electron can exicte thermally in the conduction band. Hence no conduction takes place. And the solids which have this property are called INSULATORS. In some solids the energy band gap between conduction band and valence band is less than 1eV. Due to this small amount of electron can thermally excite to the conduction band and can move freely. These solids have intermediate of CONDUCTOR and INSULATOR. And the solids which have this kind of property are called SEMICONDUCTORS. HOPE YOU UNDERSTAND!!!

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ANSWER

What derivations are there in atoms and nuclei..?

Posted by Sukirti Srivastava 6 years ago

CBSE > Class 12 > Physics

0 answers

ANSWER

What's important in optics

Posted by Meghna Sharma 6 years ago

CBSE > Class 12 > Physics

4 answers

Shruti Jha 6 years ago

In ray optics- 1. reflectionfrom spherical mirror 2. Mirror formula (convex and concave both) 3.TIR 4. Lens maker formula 5. Refraction through glass prism 6. Scattering of light 7. Optical instruments In way optics- 1.Huygen's principle 2. YDSE 3. Diffraction using single slit 4. Polarisation (These are must to be done!)

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Meghna Sharma 6 years ago

Both

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Shruti Jha 6 years ago

Ray or wave?

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Rameez Khan 6 years ago

From which????

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ANSWER

The distance of an obeject of height h' from a concave mirrior of focal lenght 10cm giving a real image of magnification 2 is ..........?

Posted by Naina Verma 6 years ago

CBSE > Class 12 > Physics

4 answers

Tamanna Sharma 6 years ago

Sorry by mistake typing it's not-10 it's -15

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Rameez Khan 6 years ago

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Tamanna Sharma 6 years ago

-10

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Rameez Khan 6 years ago

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ANSWER

The velocity of an e.m. wave in vacuum with permeability (uo) and permittivity(eo) is

Posted by Ritik Goyal 6 years ago

CBSE > Class 12 > Physics

2 answers

Muskaan Vig 6 years ago

C=1/√e°u°.......velcoity=1/root permeability root permittivity...

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Tamanna Sharma 6 years ago

1/uo×eo^1/2

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ANSWER

How to prove transverse nature of electromagnetic waves.

Posted by Meghna Sharma 6 years ago

CBSE > Class 12 > Physics

18 answers

Muskaan Vig 6 years ago

Tranverse nature of e.m. waves.....The oscillations of Electic field and magnetic field are perpendicular to each other and also to direction of propagation of em wave ...this kind of nature is of tranverse waves and thus em waves are tranverse waves in nature..

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Shruti Jha 6 years ago

I am not getting!

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Shruti Jha 6 years ago

Rameez what are you saying?

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Shruti Jha 6 years ago

With the help of polaroids. It's there in ncert!

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Rameez Khan 6 years ago

Shruti ko lyun bol ri ho

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Rameez Khan 6 years ago

????

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Rameez Khan 6 years ago

Achi ho

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Rameez Khan 6 years ago

Kyy

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Meghna Sharma 6 years ago

Kya hu mei??

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Meghna Sharma 6 years ago

Mtlb

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Rameez Khan 6 years ago

Meghna

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Meghna Sharma 6 years ago

But still i didn't get u rameez

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Meghna Sharma 6 years ago

Ty Tamanna

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Rameez Khan 6 years ago

Jo ho tm

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Tamanna Sharma 6 years ago

And another way to represent it in mathematical equation and prove no resolution of E and B

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Tamanna Sharma 6 years ago

1. They can be polarized (electric field oscillations) 2. Travel in vaccum by showing these property we can say that electromagnetic waves are transverse in nature

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Meghna Sharma 6 years ago

Means what??

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Killer Xmarty 6 years ago

La udu

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ANSWER

Koi FERMI LEVEL IN SEMICONDUCTOR samjhaana but in simple language

Posted by Meghna Sharma 6 years ago

CBSE > Class 12 > Physics

10 answers

Shruti Jha 6 years ago

I am good!

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Rameez Khan 6 years ago

Hiii...kaisi ho

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Shruti Jha 6 years ago

Hello Rameez!

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Rameez Khan 6 years ago

Hlwwww

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Killer Xmarty 6 years ago

Sry shruti

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Killer Xmarty 6 years ago

Hii shriti

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Shruti Jha 6 years ago

Anytime girl!☺

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Meghna Sharma 6 years ago

Kk ty i got it

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Shruti Jha 6 years ago

I hope this makes you understand!

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Shruti Jha 6 years ago

Fermi level is the highest energy state occupied by electrons in a material at absolute zero temperature. As the temperature is increased, electrons start to exist in higher energy states too.

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ANSWER

Calculate the peak value of the magnetic field vector of a plane radiowave that has peak electric field 50

Posted by Prakash Gupta 6 years ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 6 years ago

50 as the magnitude of both E and B in em waves is equal and direction is perpendicular

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ANSWER

Construct a refracted wavefront using Huygens principle, when a plane wavefront is incidented on a plane surface from an optically denser medium.

Posted by Lakshayraj Singh Sonigra 6 years ago

CBSE > Class 12 > Physics

1 answers

Shruti Jha 6 years ago

It is given in ncert!

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ANSWER

Is Question paper in the board will be come like a sample paper pattern ?

Posted by Pritesh Singh 6 years ago

CBSE > Class 12 > Physics

4 answers

Pritesh Singh 6 years ago

Sara jo sample paper me jo chapter sa jaisa question pucha gya hai uske according hi rhega ya different

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Prabhat Emmanuel 6 years ago

Yeah Dude it is will be like a sample paper .

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Meghna Sharma 6 years ago

Of course yes but cant say anything

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Vinay Gautam 6 years ago

Yes

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ANSWER

Dynamic lift is related to

Posted by Sunilkumar Ks 6 years ago

CBSE > Class 12 > Physics

1 answers

Shruti Jha 6 years ago

Dynamic lift is the force that acts on a body by virtue of its motion through a fluid. Ye mene 11th me padha h 12th me aisa kuch h kya?

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ANSWER

Ek gal daaso what about vande graff generator? Karna hain kya? Cuz' school mein Sir ne nahi karvaya tha he said that it's not in our board portion! But i saw this question in 2016 exam paper??? Bataye zara

Posted by Shruti Jha 6 years ago

CBSE > Class 12 > Physics

8 answers

Shruti Jha 6 years ago

Okay! Thank you devender!

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Vinay Gautam 6 years ago

Yes dheeraj is right ye syllabus m na h

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Shruti Jha 6 years ago

Dheeraj, you sure na?

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Dr. Dheeraj Kumar 6 years ago

It is nit in our syllaybus

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Shruti Jha 6 years ago

Wokays, Nancy!

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Nancy Verma 6 years ago

Pta nhi bt mere sir ne krya hai to mere hisab se tyar kr lo

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Shruti Jha 6 years ago

Kya kehta hain naya pattern?

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Rounak Kumar Singh 6 years ago

Suno madam is baar nya pattern set hua hai..so latest syllabus pe kaam kijiye ...thank you

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ANSWER

A satellite is moving in a circular orbit at a height 100 km above the earth surface a person inside the satellitte feel weightless because A.Acceleration dye to gravity is almost zeroat such a height B.the earth does not exert any force on the person C.the centripetal force makes the satellitte move in a circular orbit D.the force due to earth and the moon are almost compensated at such a height

Posted by Sunilkumar Ks 6 years ago

CBSE > Class 12 > Physics

2 answers

Tamanna Sharma 6 years ago

The correct option is 3. As we know here the only gravitational force acting on the satellite by earth responsible for centrifugal force (moves in circular orbit) and hence F gravity = normal (weight of person) + centrifugal force, Fg= centrifugal force, hence weight =0, as condition of weightlessness, l hope this would be a clear explanation to you ..as per (centripetal = centrifugal)

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Shruti Jha 6 years ago

I think the answer should be A. Cuz' as satellite accelerate towards the Earth, the earth curves away beneath them and they don't get closer. So the person feels weightless. Also, please correct me if i am wrong!

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ANSWER

A satellite orbits around the earth in a circular orbit with a speed v and orbital radius r if it losses some energy then v and r changes as A.v decrease and r increase B.both v and r decrease C.v increase r decrease D.both v and r increase

Posted by Sunilkumar Ks 6 years ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 6 years ago

A. As it's base theorm for" mission mangal"

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ANSWER

Transistor syllabus mei h?

Posted by Meghna Sharma 6 years ago

CBSE > Class 12 > Physics

6 answers

Killer Xmarty 6 years ago

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Kusum Joshi 6 years ago

Nahi

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Nancy Verma 6 years ago

No it is not

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Rounak Kumar Singh 6 years ago

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Meghna Sharma 6 years ago

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Shruti Jha 6 years ago

Naa rey

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ANSWER

Is doping in syllabus??

Posted by Meghna Sharma 6 years ago

CBSE > Class 12 > Physics

3 answers

Devyani Malvi 6 years ago

Yes absolutely ?

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Navneet Kumar 6 years ago

Yes

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Tapan Pandey ?? 6 years ago

Yes

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ANSWER

What are the posible questions can be ask in 2019-2020

Posted by Taj Taj 6 years ago

CBSE > Class 12 > Physics

2 answers

Vinay Gautam 6 years ago

Cyclotron surely aaayega 5 no ka

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Kusum Joshi 6 years ago

Cyclotron can be ask.

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ANSWER

Arre can anyone tell me ki kisi ne physics mei cryatalline n amorphous solids padha h???REPLY N BE QUICK PLZZZZZZ

Posted by Meghna Sharma 6 years ago

CBSE > Class 12 > Physics

4 answers

Tushar Bhola 6 years ago

They ask about crysatalline and amorpous solid which not in our physics and in chemistry it get left from CBSE

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Vinay Gautam 6 years ago

I doesnt think so

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Shruti Jha 6 years ago

Ye semiconductors me hain bhi?

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Meghna Sharma 6 years ago

Asking in semiconductors

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ANSWER

What is polarisation if light

Posted by Shivam Singh 6 years ago

CBSE > Class 12 > Physics

1 answers

Mercury Dragon 6 years ago

It means the plane of elictric and magnetic field oscillation is fixed ....and not random

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ANSWER

Can anyone tell me is doing only ncert for physics a good idea??

Posted by Khushi Singh 6 years ago

CBSE > Class 12 > Physics

4 answers

Khushi Singh 6 years ago

Obviously prabhat ik that only ncert is not a good idea i just asked whether i should even study it or not ??

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Vinay Gautam 6 years ago

Not at alll

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Prabhat Emmanuel 6 years ago

Not enough For board also last years paper is important. Solve Arihant chapterwise sample paper.

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Nancy Verma 6 years ago

Yes because new pattern is based on ncert

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ANSWER

Doppler effect syllabus me h is session 2019-2020 me ya nhi

Posted by Abhishek Harit 6 years ago

CBSE > Class 12 > Physics

4 answers

Vinay Gautam 6 years ago

Hai yrrr

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Meghna Sharma 6 years ago

Ty shruti for awaring

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Shruti Jha 6 years ago

Haanji hain!

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Meghna Sharma 6 years ago

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ANSWER

Howz ur preparation going on.

Posted by Meghna Sharma 6 years ago

CBSE > Class 12 > Physics

2 answers

Meghna Sharma 6 years ago

Upar se yaa neeche se. ???

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Anuj Maurya 6 years ago

Full on Rocking ???

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ANSWER

The surface densities on the surfaces of two charged spherical conductors of radii R1 and R2 are equal .The ratio of electric intensities on the surface is what???? Koi hai to pls help me

Posted by Nancy Verma 6 years ago

CBSE > Class 12 > Physics

5 answers

Tamanna Sharma 6 years ago

It's ok

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Nancy Verma 6 years ago

Thankyou tamanna

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Tamanna Sharma 6 years ago

If surface density is same then sigma1= q1/A1, sigma2=q2/A2 if surface density are equal then sigma1= sigma2 thenE1/E2 = Kq1×R2^2/R1^2xKq2 multiply numerator and denominator by 4 pie and now whole expression cancel out =1

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Nancy Verma 6 years ago

Kaise aaya pls tell me

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Tamanna Sharma 6 years ago

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ANSWER

Use gauss law to prove that the elactric field inside a uniformly charged spherical shell is zero

Posted by Darshan ? 6 years ago

CBSE > Class 12 > Physics

10 answers

Rameez Khan 6 years ago

Bhk be

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Killer Xmarty 6 years ago

Kuch nhi

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Shruti Jha 6 years ago

Kya hua hain Rameez? Ayaan wants to know?

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Killer Xmarty 6 years ago

Shruti ???

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Shruti Jha 6 years ago

Thank you Rameez also thank you Rajat for the correction!

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Rajat Barwar 6 years ago

I think the below given answer is half correct, by doing this we get the integral equal to zero which may have two cases, 1) the electric field is zero. 2) the integral at one part is cancelled out by other part hence overall it comes out zero. Hence to prove that it is not the second case,simply we have to mention a extra line that ,because the charged sphere is a symmetrical body hence E should be constant all over and hence can not cancel out ,which means it is zero.... Hope this may help you....

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Killer Xmarty 6 years ago

Nice answer shruti

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Shruti Jha 6 years ago

Charge enclosed that is q=0 Which means no charge is enclosed inside the spherical shell. Hence, using gauss law; Put 0 in place of q and 0 divide by apsilamnot is 0.

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Darshan ? 6 years ago

Answer plzz

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Vidit Dixit 6 years ago

That's is one of tha most common answer......even i also dont about it ?

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ANSWER

To those who are thinking that they won't able to pass the boards exam due to less study or whatever the reason must be:) First of all have faith in yourself. You still have time. Go through most asked derivations and laws. Practise previous year papers atleast twice to thrice. Also, don't do all these with pressure and in tension. Just Chillax and give your 100% with relaxed mind and heart. All the Best. You can do it. After all life won't end if you don't score well! Just study peacfully!

Posted by Shruti Jha 6 years ago

CBSE > Class 12 > Physics

21 answers

Rameez Khan 6 years ago

Hmm

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Shruti Jha 6 years ago

Ueah!

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Rameez Khan 6 years ago

Okk...Aap kh ri ho tgk

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Shruti Jha 6 years ago

No isuue!

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Rameez Khan 6 years ago

But they r starting

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Rameez Khan 6 years ago

Okkk....sry jn

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Shruti Jha 6 years ago

Sab bohot acche hain!!!

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Shruti Jha 6 years ago

Not again Rameez!

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Shruti Jha 6 years ago

????????????????????? Meghna and Ayaan- why both of you are laughing?

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Meghna Sharma 6 years ago

??????

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Killer Xmarty 6 years ago

Shruti ?

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Shruti Jha 6 years ago

I am here only!

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Killer Xmarty 6 years ago

Love u byyy

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Killer Xmarty 6 years ago

Acha kahan chali gyi yrrr phr

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Shruti Jha 6 years ago

Jaag rahi hu Rameez!

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Shruti Jha 6 years ago

Truly said Ayaan!

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Nancy Verma 6 years ago

Yes dear u r right

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Tamanna Sharma 6 years ago

You are right Ayaan

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Killer Xmarty 6 years ago

So gyi kyaa???

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Killer Xmarty 6 years ago

??????

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Killer Xmarty 6 years ago

Yess

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ANSWER

Is LC oscillator there in physics syllabus this year?

Posted by Mahi D 6 years ago

CBSE > Class 12 > Physics

4 answers

Navneet . 6 years ago

Yes

1Thank You

Adi Kumar 6 years ago

No only diagram and definition

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Tamanna Sharma 6 years ago

Yes mahi

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Shruti Jha 6 years ago

Yes!

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ANSWER

What about series and parallel combination of power consumed? Do we have to do derivation?

Posted by Shruti Jha 6 years ago

CBSE > Class 12 > Physics

2 answers

Shruti Jha 6 years ago

Okay! Thank you.

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Tamanna Sharma 6 years ago

Derivatives are not necessarily ask in paper but its application is definitely cpme like brightness of bulb.

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ANSWER

Accha koi imp topics hi bata do from dual nature and Alternating Current!

Posted by Shruti Jha 6 years ago

CBSE > Class 12 > Physics

6 answers

Shruti Jha 6 years ago

Dear tamanna, I completed these both chapters just wanna ask on what to focus more! That's why. Thank you.

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Tapan Pandey?? 6 years ago

Ek no.tamanna

1Thank You

Tamanna Sharma 6 years ago

O me ka kudi tu pure sall wich ki kardi se,jo ena confuse ho re aa ee sare basic topic nal,honn tusi NCERT aur previous year questions kar lo ehh voht he tuhade nal, sasriya kal ji, good night ???

4Thank You

Nikita Beniwal 6 years ago

In alternating current transformer LCR power factor resonance

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Nikita Beniwal 6 years ago

Numerical from Einstein equation

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Nikita Beniwal 6 years ago

In dual nature graphs r very important

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ANSWER

Can anyone please tell me that what should i read from ch-2 bcz the ch is so boring nd i have to cover it...