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

A pn junction made up of compound semiconductor with metallised contacts..when it is forward biased through a series resistance r , light photons are emitted from the non-metallised surface of the p-region. The series resistance r limits the current through the led and hence controls the intensity of light emitted by it

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The variation of potential difference v with length l in case of two potentiometers x and y is shown in the fig. which one of these two will you prefer for comparing emf of two cells and why?

Posted by Kartik Gupta 8 years ago

CBSE > Class 12 > Physics

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What is the working Of Led

Posted by Jainab Khan 8 years ago

CBSE > Class 12 > Physics

0 answers

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Imp question for cbse 2018

Posted by Samagya Lama 8 years ago

CBSE > Class 12 > Physics

0 answers

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Electric potential due to anypoint due to a dipole

Posted by Aditya Kumar 8 years ago

CBSE > Class 12 > Physics

1 answers

Akash Agarwal 8 years ago

Kpcos©/R^2

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Find the expression for the electric feild intensity at a point on the axis of uniformly charge ring

Posted by Roshan Shukla 8 years ago

CBSE > Class 12 > Physics

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Why semiconductors are electrically neutral

Posted by Pankaj Sihag 8 years ago

CBSE > Class 12 > Physics

3 answers

Radhika Tyagi 8 years ago

Bs yhi unit ati h mko to?

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Garima Suyal 8 years ago

Yes ayushi is right

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Radhika Tyagi 8 years ago

Bcz they possess equal no of holes and electrons

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important topic in the semiconductor chapter

Posted by Shobhitha Shetty 8 years ago

CBSE > Class 12 > Physics

3 answers

Surbhi Raghu 8 years ago

Transistor in CE mode

1Thank You

Trisha Kumari 8 years ago

Logic gates

3Thank You

Pranjali Mahajan 8 years ago

Full wave half rectifiers transistors

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Which are the important derivation for class 12 boards in physics

Posted by Janvi Golechha 8 years ago

CBSE > Class 12 > Physics

1 answers

Trisha Kumari 8 years ago

From my side ... Derivation are not important as ...less chances are there.....for coming in board ...but it's up to you that what to do... Capacitance derivation are important... Microscope...are also there..

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(b) A horizontal conducting rod 10 m long extending from east to west is falling with a speed 5·0 ms –1 at right angles to the horizontal component of the Earth’s magnetic field, 0·3 10 -4Wb m–2 . Find the instantaneous value of the emf induced in the rod

Posted by Smile Jaiswal 8 years ago

CBSE > Class 12 > Physics

0 answers

ANSWER

What do you understand by electromotive force?state it's SI unit.

Posted by Kartik Gupta 8 years ago

CBSE > Class 12 > Physics

1 answers

Namami Shukla 8 years ago

Emf is the potential difference across the terminals when no current is flowing through the circuit i.e. circuit is open and its SI unit is volts..

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Angular spread

Posted by Om Jha 8 years ago

CBSE > Class 12 > Physics

0 answers

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What is drift velocity??

Posted by Shweta Gupta 8 years ago

CBSE > Class 12 > Physics

2 answers

Ankita Bhardwaj 8 years ago

Drift velocity is the average velocity with which the free electrons move towards the positive end of a conductor under the influence of external electric field applied.

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Anjali Gupta 8 years ago

Average velocity gaind by an free electrons of a conductor in the opposite direction of electric field is called drift velocity

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to which of the two a polar dielectric or a non polar dielectric does a paramagnetic material correspond?justify answer

Posted by Archana Chaudhary 8 years ago

CBSE > Class 12 > Physics

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A capacitor blocks d.c but allows a.c to pass.explaine

Posted by Sandhya Raj 8 years ago

CBSE > Class 12 > Physics

1 answers

Radhika Tyagi 8 years ago

Frequency of d.c. is 0. Therefore capacitance becomes 0 and hence capacitor blocks d.c. and allows ac to pass

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Do electromagnetic wave carry energy and momentum?

Posted by Sohaib Akhtar 8 years ago

CBSE > Class 12 > Physics

2 answers

Pranjali Mahajan 8 years ago

Yes its one of their property

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Aisha Grewal 8 years ago

Yes

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Is cyclotron moving coil galvanometer a.c. Generator diffraction due to single slit important

Posted by Ashutosh Pratap Singh 8 years ago

CBSE > Class 12 > Physics

2 answers

Aisha Grewal 8 years ago

Haan ji

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Muskaan Gugnani 8 years ago

Yes

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Why can't we clearly see through fog

Posted by Mohit Soni 8 years ago

CBSE > Class 12 > Physics

1 answers

Aisha Grewal 8 years ago

Due to scattering of light

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What topics are deleted from the syllabus

Posted by Charu Chauhan 8 years ago

CBSE > Class 12 > Physics

5 answers

Radhika Tyagi 8 years ago

Yup

1Thank You

Charu Chauhan 8 years ago

R u sure

1Thank You

Radhika Tyagi 8 years ago

Transistor as switch or defects of eye

1Thank You

Ritu Gupta 8 years ago

transistor is in the syllabus. transistor as oscillator is not in the syllabus

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Ashutosh Pratap Singh 8 years ago

Oscillator,vaan der graaf generator and transistor

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Short

Posted by Gurpreet Sandhu 8 years ago

CBSE > Class 12 > Physics

1 answers

Radhika Tyagi 8 years ago

?? ?

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Oswal or arihant

Posted by Kristina Sarang 8 years ago

CBSE > Class 12 > Physics

2 answers

Saksham Sawarna 8 years ago

Arihant

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Sai Thaini 8 years ago

Arihant

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I heard that cbse doesn't ask derivative much only applications type questions is ask is it true

Posted by Kristina Sarang 8 years ago

CBSE > Class 12 > Physics

1 answers

Sai Thaini 8 years ago

Yeah. Derivations aren't much asked (which doesn't mean they are not asked at all) cause there are candidates who have taken pure science, they may not know integrals and all.

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Derivation of the energy stored in the parallel plate capacitor

Posted by Shashank Pandey 8 years ago

CBSE > Class 12 > Physics