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

Not sure but may be photometal is the metal that can release electrons when a light of suitable frequency is incident on it (or shows photoelectric effect)...

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What is walfer?

Posted by Tamanna Sharma 5 years, 10 months ago

CBSE > Class 12 > Physics

3 answers

Yuvraj Singh 5 years, 10 months ago

A wafer (also called a slice or substrate) is a thin slice of semiconductor, such as a crystalline silicon , used for the fabrication of integrated circuits and to manufacture solar cells.

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Tamanna Sharma 5 years, 10 months ago

Sorry it's a spelling error it's wafer not walfer ( semi conductors )

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Riya Rana 5 years, 10 months ago

In what context is it being refered as in here ?

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Why a photo diode is operated in reverse bias connection?

Posted by Abhishek Sah 5 years, 10 months ago

CBSE > Class 12 > Physics

2 answers

Riya Rana 5 years, 10 months ago

In reverse biasing the depletion is wider so more amount of light can be captured plus to easily observe the changes in current with the change in intensity of the incident light.

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Tamanna Sharma 5 years, 10 months ago

Because in reverse bias it is easy to observe change in current with change in light intensity

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How zener diode act as voltage regulator?

Posted by Abhishek Sah 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 5 years, 10 months ago

When reverse bias voltage reaches the breakdown voltage, then there is a large change in current and after that just above breakdown voltage large change in the current is insignificant change in reverse bias voltage and use as a voltage regulator

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On which principal does potentiometer work

Posted by Utpal . 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 5 years, 10 months ago

Potential gradient: whena steady current is flows through a wire AB then there is a fall of potential along the wire fromA to B

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ImportantDerivation of physics

Posted by Utpal . 5 years, 10 months ago

CBSE > Class 12 > Physics

2 answers

Kunal Kumar 5 years, 10 months ago

Electric dipole along axial and equatorial line, gauss theorem, electric potential, youngs double slit exp, etc

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Raman Kant 5 years, 10 months ago

Compound microscope

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Which topics very important.

Posted by Himanshu Prasad 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Ɽøⱨł₮ ₲Ʉ₱₮₳ 5 years, 10 months ago

Current electricity ray optics wave optics magnetism

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We are having doubt in physics can we ask question in this app??

Posted by Himanshu Prasad 5 years, 10 months ago

CBSE > Class 12 > Physics

5 answers

Aditya Chauhan 5 years, 10 months ago

Accha

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Tamanna Sharma 5 years, 10 months ago

We are welcoming you

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Tamanna Sharma 5 years, 10 months ago

No only you never ask questions here ????? l am just kidding of course you ask your's queries here at all time

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Ankit Bishwakarma 5 years, 10 months ago

Of course

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Kanchan Choudhary Jat 5 years, 10 months ago

Of course

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Electric field intensity due to group of charges

Posted by Gagan Deep 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Riya Rana 5 years, 10 months ago

Gagan, electric field intensity at any point due to a group of charges is equal to the VECTOR sum of electric field intensities due to INDIVIDUAL charges.

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Is Junction Transistor In CBSE 2019-20 Syllabus?

Posted by Shubhashish Ranjan 5 years, 10 months ago

CBSE > Class 12 > Physics

3 answers

Ankit Bishwakarma 5 years, 10 months ago

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Shubhashish Ranjan 5 years, 10 months ago

ThankYou ☺

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Mahi D 5 years, 10 months ago

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Posted by Mahi D 5 years, 10 months ago

CBSE > Class 12 > Physics

2 answers

Tamanna Sharma 5 years, 10 months ago

What you want to ask

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Mahi D 5 years, 10 months ago

Three concentric spherical metallic shells A , B and C of radii a , b and c (a<b<c) have charge densities σ,−σandσ respectively . If the shells A and C are at the same potential then the relation between a , b and c is? I am unable to upload this question fully in ask questions section.maybe some issue is there.. Pls answer this here.

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Posted by Mahi D 5 years, 10 months ago

CBSE > Class 12 > Physics

2 answers

Riya Rana 5 years, 10 months ago

Mahi you can write the question directly...

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Mahi D 5 years, 10 months ago

This question is not uploaded fully aven after writing the whole question in ask section.. can anyone tell what has gone wrong??

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In exemplar ,it is given that electric field is continuous if there is no charge at that point and discontinuous if there is a charge present at that point, so logically if field is affected due to the charge presence then according to the relation F=qE ,force also have to affected by this. But we study force is not affected by the presence of other charge. Please explain if you have explanation for this .

Posted by Tamanna Sharma 5 years, 10 months ago

CBSE > Class 12 > Physics

4 answers

Tamanna Sharma 5 years, 10 months ago

Can you please explain this with the electric field as l mension in my query and l know superposition principle and my question is different

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Vaibhav Srivastava 5 years, 10 months ago

According to superposition principle force on a charge by the group of charges are the vector sum of the forces of all the charges. Now just think of a system of charges A and B. The force on A is due to charge B. If a charge C is put in the system then the net force on A will be the vector sum of the forces produced by the charges B and C but the force between A and B remains same. This way we can say that the force is a two body interaction and hence cannot be affected by the third body.

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Riya Rana 5 years, 10 months ago

Ohh yeah... Good question..

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Tamanna Sharma 5 years, 10 months ago

If you want to check it go for Q 1.9 in MCQ type ll in NCERT Exemplar

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What is the weightage of theory and numericals in physics

Posted by Yakuza Shimatoro 5 years, 10 months ago

CBSE > Class 12 > Physics

4 answers

Tamanna Sharma 5 years, 10 months ago

For both of you I want to tell that more portion of paper is conceptual ,graphs and understanding based and pure numerical portion is less in board,go and check it on cbse site .

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Shubhashish Ranjan 5 years, 10 months ago

Wrong...There Is No Specific Weightage For Theory And Numerical Section But Be Prepared For More Numericals Because The Pattern Is Changed And There Must Be More Questions On Application.

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Balram Sharma 5 years, 10 months ago

No you are wron

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Tamanna Sharma 5 years, 10 months ago

70% theory and 30% numerical

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I want a list of all deleted topics from CBSE syllabus this year 2019 please list them all chapter wise

Posted by Ankit Beniwal 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Shubhashish Ranjan 5 years, 10 months ago

Go Through Official Website Of CBSE.☺

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I know it's a silly question but l am just confused in it. Q: we know current is a scalar(more accurately tensor) quantity and area is also a scalar quantity, then how current density is a vector quantity. Please clear this confusion??

Posted by Tamanna Sharma 5 years, 10 months ago

CBSE > Class 12 > Physics

9 answers

Tamanna Sharma 5 years, 10 months ago

What are you saying divya it's totally crazy

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Divya Shrivastav 5 years, 10 months ago

area is a vector quantity and it is independent from its surface

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Riya Rana 5 years, 10 months ago

No area is not a vector quantity it actually is a scalar quantity but we make it vector by using UNIT VECTOR concept.

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Tamanna Sharma 5 years, 10 months ago

Shubhashish all times area is not a vector in some cases we consider it as area vector,but you don't say that area is a vector quantity. REASON inorder to consider area as a vector because of the orientation factor and for simplification we use projection area means resolved form of area in the direction of the another quantity like field. But here l want to ask a small integral area not consider the whole area so how at this time we can say that J is a vector quantity, we always we study it as a vector.

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Mahi D 5 years, 10 months ago

We consider area vector here which is normal to the plane so area is a vector and current is scalar.

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Shubhashish Ranjan 5 years, 10 months ago

Area Is A Vector Quantity. ☺

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Shubhashish Ranjan 5 years, 10 months ago

Area Is A Vector Quantity.☺

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Tamanna Sharma 5 years, 10 months ago

In many books there is no explanation, they directly write it as a vector quantity.,so if you know any website ,where this is well explained, please share it with me.

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Riya Rana 5 years, 10 months ago

Refer to unit vector from class 11 it was well explained there if you remember.

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If the charge is placed on the gaussian surface, is it will be consider in finding out flux.explain with a suitable reason.

Posted by Tamanna Sharma 5 years, 10 months ago

CBSE > Class 12 > Physics

4 answers

Tamanna Sharma 5 years, 10 months ago

But why we don't consider this charge .what is the reason behind this ,please ask this question to your teacher as l asked this question to my physics teacher 6 times but except 1 time ,each time ,he says shut up and don't disturb the class.

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Mahi D 5 years, 10 months ago

Hey Tamanna , I looked for this in sl arora ... According to defination, gaussian surface is a closed surface enclosing a charge but it is written nowhere that if the charge is on gaussian suface then it is not considered . I could tell this much only.. if you clear this confusion then please tell the answer here also.

1Thank You

Tamanna Sharma 5 years, 10 months ago

But my teacher told me that charge must be inside this gaussian surface, not on surface can you please, verify my query, like this type problem given in any book.

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Mahi D 5 years, 10 months ago

Yes it will be considered. We imagine a gaussian surface so that the the point at which flux is to be calculated lies on it. You can see the application of gauss theorem . We construct gaussian surfaces ourselves to find flux on a given point.

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Can a polarized light make again an unpolarized light. If yes, then suggest a method.

Posted by Tamanna Sharma 5 years, 10 months ago

CBSE > Class 12 > Physics

2 answers

Tamanna Sharma 5 years, 10 months ago

I don't understand ,which angle change or is there any specific device to do this ,please tell me so that this will enhance my understanding.

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Riya Rana 5 years, 10 months ago

Yes by change in angles

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Diode and zenner diode with characteristics

Posted by Gaurav Shekhar 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Riya Rana 5 years, 10 months ago

Zener diode's main characteristic is to act as a volatge regulator. It acts as voltage regulator by supplying excess heavy current and excess voltage across the Rs resistor when the incoming fluctuating volatge exceeds the breakdown voltage.

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What is the force b/w parallel plate capacitor?

Posted by Bhaskar Rij Rij 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Riya Rana 5 years, 10 months ago

E=sigma/E●. F=q×E so... F=sigma×q/E●

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Why they use only magnin in preparation of...magnetic wires in d magnetic bridges??

Posted by Ayaan Ali ?? 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Riya Rana 5 years, 10 months ago

Magnin is a alloy. Alloys have high resistivity and very low temperature coefficient. Magnin is used in the magnetic wires because it the ONLY alloy that is completely independent of temperature (lowest temperature coefficient).

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Please tell me the impt topics from ch-14 semiconductor for preparation of boards?

Posted by Sarthak Jain 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Riya Rana 5 years, 10 months ago

Semiconductors is coming for 7 MARKS in BOARDS it is a highly important chapter apparently ( even more than electrostatics ) and when it comes to topics you should do entire chapter thoroughly but most importants are DIODES (all four types) and HALF WAVE AND FULL WAVE RECTIFIER !!

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Tow wireof copper and other of manganin have same resistance and equal length.which wire is thicker and why

Posted by Ravi Verma 5 years, 10 months ago

CBSE > Class 12 > Physics

1 answers

Madan Kumar 5 years, 10 months ago

Manganin wire is thicker than copper wire Due to resitivity is directly proportional to area, therefore. Area of manganin is greater than area of copper. So, it is thicker.

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Microscope and telescope derivation at near point and infinity

Posted by Chamba Gyasto 5 years, 10 months ago

CBSE > Class 12 > Physics