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polaroids questions

Posted by Chakshu Sharma 7 years ago

CBSE > Class 12 > Physics

0 answers

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Bhai koi पास kra dene वाले topic's bata do अपनी तो लगी padi है

Posted by Nikhil Kumar 7 years ago

CBSE > Class 12 > Physics

1 answers

Sonal Sonal 7 years ago

Transeformer,acgenerater, rectifier,cyclotron,galvanometer,lenmeker formula, capictance base question, ypungs experiment ye question jrur kr liyo baki tumhari marji

2Thank You

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What are the limitations of ohm 's law?

Posted by Sunita Tiwari 7 years ago

CBSE > Class 12 > Physics

3 answers

Riddhi Dey 7 years ago

There are mainly 3 limitations: 1) In certain cases for a good conductor, V ceases to be directly proportional to I. 2) The magnitude of current is not the same for equal magnitude of V of opposite directions, like in diodes. 3) In materials like LED (where GaAs is used), there are multiple values of V for same same value of I, i.e., the relation between V and I is not unique. It can also be included that Ohm's law is held only at a fixed system of conditions.

1Thank You

Aakriti Choudhary 7 years ago

1.Ohms law is applicable for ohmic conductors 2. To validate ohms law there must be a constant temperature. 3. Ohms law is not applicable for non ohmic conductors

1Thank You

Rishabh Pandey 7 years ago

There must be constant temperature to validate ohms law

1Thank You

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What is tunnel effect?How does the kinetic energy of alpha particle related with Q-value?

Posted by Amardeep Prasad 7 years ago

CBSE > Class 12 > Physics

0 answers

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The intensity at the central maxima in YDSE is I○ find out the intensity at a point where the path difference is lameda/6,lameda/4 and lameda/3

Posted by Suhani Rana? 7 years ago

CBSE > Class 12 > Physics

0 answers

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Speed of the light

Posted by Prateek Madhav 7 years ago

CBSE > Class 12 > Physics

1 answers

Sameer Khan 7 years ago

3*10power raise to 8 m/s

3Thank You

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Bai mai physics ke sbi article or derivations or main topic read kro to pass hojoga

Posted by Akash Deep Singh 7 years ago

CBSE > Class 12 > Physics

1 answers

Dsd Zss 7 years ago

Yes but do the derivation properly

3Thank You

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Discuss faraday law of electromagnetic induction?

Posted by Jaydeep Mathrani 7 years ago

CBSE > Class 12 > Physics

1 answers

Gaurav Seth 7 years ago

Faraday’s laws of Induction

First law: -

According to the first law an emf is induced in the circuit whenever the amount of magnetic flux linked with a circuit changes.
Current was induced because of magnetic flux, as there is some current in the circuit therefore there will be some emf flowing in the circuit.
Whenever the amount of magnetic flux linked with the circuit changes only at that time emf is induced.
The induced emf will be there till there is change in the flux.
When the magnet was moved then only there was change in the flux.
As the magnet is moving the number of magnetic lines crossing the area is also changing.
There is a change in the flux therefore there is induced emf.
If the magnet is not moving, there will be no change in the amount of magnetic flux so there is no induced current.

Second law: -

According to the second law the magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit.
Emf which is induced will depend upon rate at which the magnetic flux is changing.
Mathematically:-
- Let Φ1 = flux at initial time t=0.
- Φ2 = flux after time t.
- Rate of change of flux=(Φ2 – Φ1)/t =dΦ/dt
According to Faraday’s law:-
- Induced emf e ∝ (dΦ/dt)
- Experimentally the constant of proportionality was found to be 1 in all cases.
Therefore e=(dΦ/dt)
- Consider a coil which has N number of turns;Therefore
- e = N(dΦ/dt)

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What is DE Broglie wave?

Posted by Ronald Hunter 7 years ago

CBSE > Class 12 > Physics

1 answers

Niwas Basnetz 7 years ago

Lamda =h/p

0Thank You

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Why is the transmission of signals through a coaxial cable not possible for frequencies greater than 20 megahertz?? Urgent..

Posted by Vaibhav Singh Negi 7 years ago

CBSE > Class 12 > Physics

1 answers

Mahaalakshmi Vijayamoorthy 7 years ago

No. We can use it for transmission.

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Which is the best method of reducing current in an AC circuit and why?

Posted by Vaibhav Singh Negi 7 years ago

CBSE > Class 12 > Physics

2 answers

Vaibhav Singh Negi 7 years ago

It lowers the voltage and increases the current..so how is current reduced in it??

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Sarthak Bhai 7 years ago

Step down transformer

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How the conductivity of semiconductor increases with increase in temperature

Posted by Pragnya Mohalik 7 years ago

CBSE > Class 12 > Physics

4 answers

Rishabh Jain 7 years ago

Bcoz it's alpha or temperature coefficient is negative

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Sonal Sonal 7 years ago

Formula of resistivity is m/n×esquear×to and temperatur is directly portional to n(no. Density )than if temp increase n while also increase and acc to the formula if n increase resistivity while be decrease and conductivity is equal to 1upon resistivity so if resistivity decrease conductivity incerase in semicondutor

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Ashok Kumar 7 years ago

Because the photosensitive metal's electron get energy and excited from valence band to conduction band

2Thank You

Rahul Choudhary 7 years ago

Because some electron get enough energy to jump on conduction band from valence band

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Friends how is your preparations going on

Posted by Abc Kamboz 7 years ago

CBSE > Class 12 > Physics

1 answers

Nitika Neb 7 years ago

Not upto expectations and what about you

1Thank You

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A electron is placed in a uniform electric field directed along the positive X axis .In which direction , will it tend to move?

Posted by Naman Malik 7 years ago

CBSE > Class 12 > Physics

2 answers

Ashok Kumar 7 years ago

It is move in -ve x axis

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Kartik Periwal 7 years ago

-ve x axis

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Relative permiablity o of a vector b o r is equal to 0.5 identify the nature of the negative material and write its relation and magnetic susptibility

Posted by Deepshikha Yadav 7 years ago

CBSE > Class 12 > Physics

2 answers

Sonal Sonal 7 years ago

It is paramagnetic in nature not dimagnetic because its permiablity is not negative it is positive and small so it is paramagnetic in nature Relation is permiability =1+suceptibility

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Vishali Raina 7 years ago

Nature of material os diamagnetic and its relation with suseptibility is --> Permiability =1+suceptibility

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Why sky appears blue instead of violet or indigo

Posted by Mahi Yadav 7 years ago

CBSE > Class 12 > Physics

4 answers

Rishabh Jain 7 years ago

Bcoz it reflects only blue color light from White light

0Thank You

Chandan Kumar Soni 7 years ago

Because the scattering and percentage of blue light in vibgyor light is better then other colours i,s why sky appears blue

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Alok Singh 7 years ago

Eye is sensitivity from Blue colour

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Rounak Gupta 5 years, 10 months ago

ncert mai dhun

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Transmit a message signal. Calculate the peak voltage of the modulating signal in order to have a modulation index of 75%. Why modulation index generally kept less than one ?

Posted by Kartheek Chowdary Vattkuti 7 years ago

CBSE > Class 12 > Physics

1 answers

Sonal Sonal 7 years ago

Ac ki vlue to do tbhi to Am ki value nickle gi And modulating index is keep less than 1 to avoid destrotion

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Full define and principle of transformer

Posted by Rahul Chaudhary 7 years ago

CBSE > Class 12 > Physics

4 answers

Sonal Sonal 7 years ago

A transformer is a device which convert low ac voltage into high ac voltage and vice virsa. It is of two type 1.step down 2.step up Principal = it is based on mutual induction means whenever the magnetic flux link with a coil change a induce emf produce in a neighbouring coi.

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N Aaditya 7 years ago

Change in current in primary coil.not induced current.

2Thank You

N Aaditya 7 years ago

A transformer is a device that convert low a.c. voltage to high a.c. voltage or vice versa. There are two types of transformer i.e. step up and step doen .TRANSFORMER IS BASED ON THE PRINCIPLE OF MUTUAL INDUCTION. IT STATES THAT WHENEVER THERE IS INDUCED EMF IN SECONDARY COIL DUE TO CHANGE IN INDUCED CURRENT IN THE PRIMARY COIL.

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Kartheek Chowdary Vattkuti 7 years ago

Definition: Transformer is a static device which convert electrical power from one circuit to another without changing its frequency. it Step up (or Step down) the level of AC Voltage and Current. Working principle: mutual induction

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What is cavity problem in magnetic ?

Posted by Lal Chand Bairwa 7 years ago

CBSE > Class 12 > Physics

0 answers

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Principle of transformer

Posted by Rahul Chaudhary 7 years ago

CBSE > Class 12 > Physics

3 answers

Sonal Sonal 7 years ago

Mutual induction means whenever the magnetic flux link with a coil change an induce emf produce in neighbouring coil

0Thank You

Kartheek Chowdary Vattkuti 7 years ago

it works on the principle of mutual induction of two coils or Faraday Law’s Of Electromagnetic induction.

0Thank You

Mayank Moudgil 7 years ago

Mutual induction

4Thank You

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I want ro know the each and every topic of unit 10 (Communication systems).

Posted by Ayush Rawat 7 years ago

CBSE > Class 12 > Physics

1 answers

Nitika Neb 7 years ago

Now the time left is less so you should prepare 10 year of communication chapter that sufficient

2Thank You

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can u explain the concept of constructive and destructive interference with derivation

Posted by Seetaram Patel Patel 7 years ago

CBSE > Class 12 > Physics

0 answers

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Why is average power = vi/2 ?

Posted by Yashwanth Venkat 7 years ago

CBSE > Class 12 > Physics

1 answers

Yashwanth Venkat 7 years ago

Bcoz in a complete cycle it take positive and negative values so it shd be vi/2

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any suggeation to use either 10 year or xam idea.?

Posted by Sanya Bhatia 7 years ago

CBSE > Class 12 > Physics

1 answers

G K 7 years ago

NCERT + 10 years + 20 sample papers = 100 marks

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while riding the bike on highways, we observe that traffic signals turns red from green. Explain the principle that is used in maintaining traffic signals

Posted by Bhumi ... 7 years ago

CBSE > Class 12 > Physics

0 answers

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Plzz answer..An equatorial glass prism of refractive index 1.6 is immersed in water of refractive index 1.33 calculate the angle of deviation produced for ray of light incident at 40° on one face of the prism.

Posted by Suhani Rana? 7 years ago

CBSE > Class 12 > Physics

1 answers

Anuj Sharma 7 years ago

First find whether it is condition for minimum deviation or not if not then use Snell's law on first refraction and then again on second refraction then use A +$=i+E

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Principle of capacitor??

Posted by Suhani Rana? 7 years ago

CBSE > Class 12 > Physics

1 answers

Gaurav Seth 7 years ago

Principle of a capacitor : A capacitor works on the principle that the capacitance of a conductor increase appreciably when an earthed conductor is brought near it. Thus a capacitor has two plates separated by a distance having equal and opposite charges.

Parallel Plate capacitor : Consider a parallel plate capacitor having two plane metallic plates A and B, placed parallel to each other (fig) The plates carry equal and opposite charges +Q and -Q respectively.

In general, the electric field between the plates due to charges +Q and -Q remains uniform, but at the edges, the electric lines of force deviate outward. If the separation between the plates is much smaller than the size of plates, the electric field strength between the plates may be assumed uniform.

Suppose A be the area of each plate, ‘d" the separation between the plates, K the dielectric constant of medium between the plates. If is the magnitude of charge density of plates, then

This is a general expression for capacitance of parallel plate capacitor. Obviously, the capacitance is directly proportional to the dielectric constant of medium between the plates.