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 5 years, 7 months ago

Arre yr yeh to smjh aa gya

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Shruti Jha 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

0 answers

ANSWER

What's important in optics

Posted by Meghna Sharma 5 years, 7 months ago

CBSE > Class 12 > Physics

4 answers

Shruti Jha 5 years, 7 months 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 5 years, 7 months ago

Both

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Shruti Jha 5 years, 7 months ago

Ray or wave?

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Rameez Khan 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

4 answers

Tamanna Sharma 5 years, 7 months ago

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

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Rameez Khan 5 years, 7 months ago

1Thank You

Tamanna Sharma 5 years, 7 months ago

-10

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Rameez Khan 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

2 answers

Muskaan Vig 5 years, 7 months ago

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

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Tamanna Sharma 5 years, 7 months ago

1/uo×eo^1/2

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ANSWER

How to prove transverse nature of electromagnetic waves.

Posted by Meghna Sharma 5 years, 7 months ago

CBSE > Class 12 > Physics

18 answers

Muskaan Vig 5 years, 7 months 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..

1Thank You

Shruti Jha 5 years, 7 months ago

I am not getting!

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Shruti Jha 5 years, 7 months ago

Rameez what are you saying?

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Shruti Jha 5 years, 7 months ago

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

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Rameez Khan 5 years, 7 months ago

Shruti ko lyun bol ri ho

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Rameez Khan 5 years, 7 months ago

????

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Rameez Khan 5 years, 7 months ago

Achi ho

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Rameez Khan 5 years, 7 months ago

Kyy

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Meghna Sharma 5 years, 7 months ago

Kya hu mei??

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Meghna Sharma 5 years, 7 months ago

Mtlb

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Rameez Khan 5 years, 7 months ago

Meghna

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Meghna Sharma 5 years, 7 months ago

But still i didn't get u rameez

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Meghna Sharma 5 years, 7 months ago

Ty Tamanna

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Rameez Khan 5 years, 7 months ago

Jo ho tm

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Tamanna Sharma 5 years, 7 months ago

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

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Tamanna Sharma 5 years, 7 months 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 5 years, 7 months ago

Means what??

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Killer Xmarty 5 years, 7 months ago

La udu

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ANSWER

Koi FERMI LEVEL IN SEMICONDUCTOR samjhaana but in simple language

Posted by Meghna Sharma 5 years, 7 months ago

CBSE > Class 12 > Physics

10 answers

Shruti Jha 5 years, 7 months ago

I am good!

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Rameez Khan 5 years, 7 months ago

Hiii...kaisi ho

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Shruti Jha 5 years, 7 months ago

Hello Rameez!

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Rameez Khan 5 years, 7 months ago

Hlwwww

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Killer Xmarty 5 years, 7 months ago

Sry shruti

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Killer Xmarty 5 years, 7 months ago

Hii shriti

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Shruti Jha 5 years, 7 months ago

Anytime girl!☺

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Meghna Sharma 5 years, 7 months ago

Kk ty i got it

1Thank You

Shruti Jha 5 years, 7 months ago

I hope this makes you understand!

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Shruti Jha 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

1 answers

Shruti Jha 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

4 answers

Pritesh Singh 5 years, 7 months 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 5 years, 7 months ago

Yeah Dude it is will be like a sample paper .

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Meghna Sharma 5 years, 7 months ago

Of course yes but cant say anything

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Vinay Gautam 5 years, 7 months ago

Yes

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ANSWER

Dynamic lift is related to

Posted by Sunilkumar Ks 5 years, 7 months ago

CBSE > Class 12 > Physics

1 answers

Shruti Jha 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

8 answers

Shruti Jha 5 years, 7 months ago

Okay! Thank you devender!

1Thank You

Vinay Gautam 5 years, 7 months ago

Yes dheeraj is right ye syllabus m na h

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Shruti Jha 5 years, 7 months ago

Dheeraj, you sure na?

0Thank You

Dr. Dheeraj Kumar 5 years, 7 months ago

It is nit in our syllaybus

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Shruti Jha 5 years, 7 months ago

Wokays, Nancy!

1Thank You

Nancy Verma 5 years, 7 months ago

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

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Shruti Jha 5 years, 7 months ago

Kya kehta hain naya pattern?

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Rounak Kumar Singh 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

2 answers

Tamanna Sharma 5 years, 7 months 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 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 5 years, 7 months ago

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

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ANSWER

Transistor syllabus mei h?

Posted by Meghna Sharma 5 years, 7 months ago

CBSE > Class 12 > Physics

6 answers

Killer Xmarty 5 years, 7 months ago

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Kusum Joshi 5 years, 7 months ago

Nahi

1Thank You

Nancy Verma 5 years, 7 months ago

No it is not

1Thank You

Rounak Kumar Singh 5 years, 7 months ago

1Thank You

Meghna Sharma 5 years, 7 months ago

1Thank You

Shruti Jha 5 years, 7 months ago

Naa rey

1Thank You

ANSWER

Is doping in syllabus??

Posted by Meghna Sharma 5 years, 7 months ago

CBSE > Class 12 > Physics

3 answers

Devyani Malvi 5 years, 7 months ago

Yes absolutely ?

1Thank You

Navneet Kumar 5 years, 7 months ago

Yes

1Thank You

Tapan Pandey ?? 5 years, 7 months ago

Yes

1Thank You

ANSWER

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

Posted by Taj Taj 5 years, 7 months ago

CBSE > Class 12 > Physics

2 answers

Vinay Gautam 5 years, 7 months ago

Cyclotron surely aaayega 5 no ka

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Kusum Joshi 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

4 answers

Tushar Bhola 5 years, 7 months ago

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

0Thank You

Vinay Gautam 5 years, 7 months ago

I doesnt think so

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Shruti Jha 5 years, 7 months ago

Ye semiconductors me hain bhi?

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Meghna Sharma 5 years, 7 months ago

Asking in semiconductors

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ANSWER

What is polarisation if light

Posted by Shivam Singh 5 years, 7 months ago

CBSE > Class 12 > Physics

1 answers

Mercury Dragon 5 years, 7 months ago

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

1Thank You

ANSWER

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

Posted by Khushi Singh 5 years, 7 months ago

CBSE > Class 12 > Physics

4 answers

Khushi Singh 5 years, 7 months 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 5 years, 7 months ago

Not at alll

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Prabhat Emmanuel 5 years, 7 months ago

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

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Nancy Verma 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

4 answers

Vinay Gautam 5 years, 7 months ago

Hai yrrr

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Meghna Sharma 5 years, 7 months ago

Ty shruti for awaring

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Shruti Jha 5 years, 7 months ago

Haanji hain!

1Thank You

Meghna Sharma 5 years, 7 months ago

2Thank You

ANSWER

Howz ur preparation going on.

Posted by Meghna Sharma 5 years, 7 months ago

CBSE > Class 12 > Physics

2 answers

Meghna Sharma 5 years, 7 months ago

Upar se yaa neeche se. ???

1Thank You

Anuj Maurya 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

5 answers

Tamanna Sharma 5 years, 7 months ago

It's ok

1Thank You

Nancy Verma 5 years, 7 months ago

Thankyou tamanna

1Thank You

Tamanna Sharma 5 years, 7 months 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

1Thank You

Nancy Verma 5 years, 7 months ago

Kaise aaya pls tell me

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Tamanna Sharma 5 years, 7 months ago

1Thank You

ANSWER

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

Posted by Darshan ? 5 years, 7 months ago

CBSE > Class 12 > Physics

10 answers

Rameez Khan 5 years, 7 months ago

Bhk be

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Killer Xmarty 5 years, 7 months ago

Kuch nhi

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Shruti Jha 5 years, 7 months ago

Kya hua hain Rameez? Ayaan wants to know?

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Killer Xmarty 5 years, 7 months ago

Shruti ???

1Thank You

Shruti Jha 5 years, 7 months ago

Thank you Rameez also thank you Rajat for the correction!

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Rajat Barwar 5 years, 7 months 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....

1Thank You

Killer Xmarty 5 years, 7 months ago

Nice answer shruti

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Shruti Jha 5 years, 7 months 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 ? 5 years, 7 months ago

Answer plzz

1Thank You

Vidit Dixit 5 years, 7 months 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 5 years, 7 months ago

CBSE > Class 12 > Physics

21 answers

Rameez Khan 5 years, 7 months ago

Hmm

1Thank You

Shruti Jha 5 years, 7 months ago

Ueah!

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Rameez Khan 5 years, 7 months ago

Okk...Aap kh ri ho tgk

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Shruti Jha 5 years, 7 months ago

No isuue!

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Rameez Khan 5 years, 7 months ago

But they r starting

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Rameez Khan 5 years, 7 months ago

Okkk....sry jn

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Shruti Jha 5 years, 7 months ago

Sab bohot acche hain!!!

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Shruti Jha 5 years, 7 months ago

Not again Rameez!

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Shruti Jha 5 years, 7 months ago

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

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Meghna Sharma 5 years, 7 months ago

??????

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Killer Xmarty 5 years, 7 months ago

Shruti ?

1Thank You

Shruti Jha 5 years, 7 months ago

I am here only!

1Thank You

Killer Xmarty 5 years, 7 months ago

Love u byyy

1Thank You

Killer Xmarty 5 years, 7 months ago

Acha kahan chali gyi yrrr phr

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Shruti Jha 5 years, 7 months ago

Jaag rahi hu Rameez!

1Thank You

Shruti Jha 5 years, 7 months ago

Truly said Ayaan!

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Nancy Verma 5 years, 7 months ago

Yes dear u r right

1Thank You

Tamanna Sharma 5 years, 7 months ago

You are right Ayaan

2Thank You

Killer Xmarty 5 years, 7 months ago

So gyi kyaa???

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Killer Xmarty 5 years, 7 months ago

??????

1Thank You

Killer Xmarty 5 years, 7 months ago

Yess

1Thank You

ANSWER

Is LC oscillator there in physics syllabus this year?

Posted by Mahi D 5 years, 7 months ago

CBSE > Class 12 > Physics

4 answers

Navneet . 5 years, 7 months ago

Yes

1Thank You

Adi Kumar 5 years, 7 months ago

No only diagram and definition

1Thank You

Tamanna Sharma 5 years, 7 months ago

Yes mahi

1Thank You

Shruti Jha 5 years, 7 months ago

Yes!

1Thank You

ANSWER

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

Posted by Shruti Jha 5 years, 7 months ago

CBSE > Class 12 > Physics

2 answers

Shruti Jha 5 years, 7 months ago

Okay! Thank you.

1Thank You

Tamanna Sharma 5 years, 7 months ago

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

2Thank You

ANSWER

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

Posted by Shruti Jha 5 years, 7 months ago

CBSE > Class 12 > Physics

6 answers

Shruti Jha 5 years, 7 months 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?? 5 years, 7 months ago

Ek no.tamanna

1Thank You

Tamanna Sharma 5 years, 7 months 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 5 years, 7 months ago

In alternating current transformer LCR power factor resonance

1Thank You

Nikita Beniwal 5 years, 7 months ago

Numerical from Einstein equation

1Thank You

Nikita Beniwal 5 years, 7 months ago

In dual nature graphs r very important

1Thank You

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...