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

Conductor- the material which allow the electric current to pass through them eg. Copper,silver ,gold Insulator- the material which do not allow the electric current to pass through them eg. Rubber ,wood etc.

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What are eddy curents?

Posted by Shivam Verma 7 years ago

CBSE > Class 12 > Physics

1 answers

Sonu Sharma 7 years ago

Focault current - These are the current which are produced in bulk pieces of conductor . They oppose the main current and produce losses.

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What topic are out of syllabus in semiconductor

Posted by K G 5 years, 10 months ago

CBSE > Class 12 > Physics

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When a deutron of mass 2.0141u and negligible kinetic energy is absorbed by lithium (^6li3)nucleus of mass 6.0155 u ,the compound nucleus disintegrates spontaneously into alpha particles ,each of mass 4.0026 u.Calculate the energy in joules carrried by each alpha particle .

Posted by Gururaj.R. Krishiyuvan 7 years ago

CBSE > Class 12 > Physics

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what is Q factor ?(ac curent).

Posted by Aayushi Srivastava 7 years ago

CBSE > Class 12 > Physics

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Ash Thunderbird ✔ 7 years ago

The quality factor (Q) of resonance in series LCR circuit is defined as the ratio of voltage drop across inductor (or capacitor) to the applied voltage. You can say, it is an indicator of sharpness of the resonance!

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Define defraction

Posted by Utkarsh Rathaur 7 years ago

CBSE > Class 12 > Physics

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Aayushi Srivastava 7 years ago

diffraction is the phenomenon of bending of light around the corners of slits and enters into the region of geometrical shadow..

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What is the relation between external and internal resistance?

Posted by Aarti Dahiya 7 years ago

CBSE > Class 12 > Physics

1 answers

Muskan Sharma 7 years ago

r={L1/L2-1}R Where r is internal resistance and R is external resistance

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Important. Derivations

Posted by Moshin Siddiqui 7 years ago

CBSE > Class 12 > Physics

1 answers

Moshin Siddiqui 7 years ago

Ygh

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Lenz's law and energy conservation in It?

Posted by Priyanka Bisht 7 years ago

CBSE > Class 12 > Physics

1 answers

Yogita Ingle 7 years ago

Lenz’s law

According to Lenz’s law:-The polarity of the induced emf is such that it tends to produce induced current in such a direction that it opposes the change in magnetic flux that produced it.
The (-) ive sign in given equatione= (-) (dΦ/dt)tells about the direction.
According to Faraday’s law whenever there is change in the magnetic flux, emf is induced, as aresult there will be induced current.
According to Lenz’s law the direction of the induced current will be such that it opposes the change in the magnetic flux.

Lenz’s law: supports Conservation of energy

Lenz’s law obeys conservation of energy.
Magnet is moving as a result current is getting induced and when the magnet is not moving there is no induced current in the coil.
There is a mechanical energy involved with the movement of the as magnet as a result mechanical energy is converted into electrical energy which is produced by the induced current.
Magnetic energy used in moving magnet is getting transformed into electrical energy which is produced by the induced current.
This shows that Lenz’s law supports conservation of energy where one form of energy is getting transformed into another form.
Work done in moving the magnet is dissipated by Joule heating produced by the induced current.

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By bohrs postulate of atomic model, derive expression for kinetic energy

Posted by Atleeakash Akash 7 years ago

CBSE > Class 12 > Physics

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Derivation of lense maker formula

Posted by Ankit Raj 7 years ago

CBSE > Class 12 > Physics

2 answers

Gaurav Seth 7 years ago

Lens Maker Formula Derivation

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Assumptions

The following assumptions are taken for the derivation of lens maker formula.

Let us consider the thin lens shown in the image above with 2 refracting surfaces having the radii of curvatures R1 and R2 respectively.
Let the refractive indices of the surrounding medium and the lens material be n1 and n2 respectively.

Derivation

The complete derivation of lens maker formula is described below. Using the formula for refraction at a single spherical surface we can say that,

For the first surface,

For the second surface,

Now adding equation (1) and (2),

When u = ∞ and v = f

But also,

Therefore we can say that,

Where μ is the refractive index of the material.

This is the lens maker formula derivation. Check the limitations of the lens maker’s formula to understand the lens maker formula derivation is a better way.

Limitations of the lens maker’s formula

The lens should not be thick so that the space between the 2 refracting surfaces can be small.
The medium used on both sides of the lens should always be same.

Stay tuned with BYJU’S and learn more about derivation of various formulas.

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Dhanraj Patel 7 years ago

Refer S.L.ARORA for better answer

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What will be the maximum marks for the no. Of questions for numerical for this year?

Posted by Shivam Verma 7 years ago

CBSE > Class 12 > Physics

2 answers

Sunil Dutt 7 years ago

it may be of 15 to 20

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Dhanraj Patel 7 years ago

I guess they are 28

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Basic concept of displacement current

Posted by Coolest Channel B2F 7 years ago

CBSE > Class 12 > Physics

1 answers

Account Deleted 7 years ago

Due to changing electric field between the capacitor plate displacement current will produced

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Unit of intensity

Posted by Sonam Malik 7 years ago

CBSE > Class 12 > Physics

1 answers

Sayeda Iram Ateeq 7 years ago

Watt per metre square.(W/m^2)

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about the ac generator

Posted by Rajkumar Rajkumar 7 years ago

CBSE > Class 12 > Physics

1 answers

Account Deleted 7 years ago

Read your NCERT textbook

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An electron jumps from fourth to first orbit in an atom how many maximum no. Of spectral lines can be emittef by the atom to which series these lines corresspond

Posted by Babita Khatik 7 years ago

CBSE > Class 12 > Physics

1 answers

Sourav Singh 7 years ago

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Fully solved Cyclotron and transformer

Posted by Shantnu Bhati 7 years ago

CBSE > Class 12 > Physics

1 answers

Account Deleted 7 years ago

Better to read your text book

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Define one tesla using expression for the magnetic force acting on a charge 'a' moving with velocity v in a magneticfield B.

Posted by Kushum Kumari 7 years ago

CBSE > Class 12 > Physics

1 answers

Vivek Vishal Mishra 7 years ago

"Magnetic field strength at a point is 1 Tesla, if 1 coulomb of charge, when moving with a velocity of 1ms-¹ along a direction perpendicular to magnetic field, experiences a force of 1 newton ."

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Write the condition under which an electron will move undeflected in the presence of crossed electric and magnetic field.

Posted by Arti Vishwakarma 7 years ago

CBSE > Class 12 > Physics