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

But this time 20 one mark ques are also included so all the ques can't be on theory based so chance of numericals is increased. That's why 35 marks for numer....

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Gargee K 6 years, 1 month ago

No 35 marks is too much for numericals ..

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Meghna Sharma 6 years, 1 month ago

But what i heard is that this time 35 marks will be consumed by numericals. I concerned 3 teachers about this

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ANSWER

What is mean by stopping potential?

Posted by Elamurugan Malathy 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Yogita Ingle 6 years, 1 month ago

Stopping potential: The minimum negative potential given to the anode of a photocell for which the photoelectric current becomes zero is called stopping potential.

(i) The increase of frequency of incident radiation has no effect on the photoelectric current.

(ii) The photoelectric current increases proportionally with the increase in intensity of incident radiation.

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ANSWER

How are the marks Divided for each chapter?

Posted by Maga Talik 6 years, 1 month ago

CBSE > Class 12 > Physics

0 answers

ANSWER

If there is consecutively 2 slits are held 1 after 1, then what is the effects on minima and maxima , define for nth terms

Posted by Tamanna Sharma 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 6 years, 1 month ago

((((In YDSE))), please somebody tell me the ans of this question

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ANSWER

In order to define displacement current why, maxwell take a hemispherical shape for a capacitor, because if it's a fundamental law then this have to be proven for any arbitrary shape. Please explain. ???

Posted by Tamanna Sharma 6 years, 1 month ago

CBSE > Class 12 > Physics

0 answers

ANSWER

How are photodiodes fabricated? (Most frequently asked question recently)

Posted by Riya Rana 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Mahi D 6 years, 1 month ago

The light should be allowed to fall near the junction so that electron hole pairs are generated by the energy of the photons of incident light.

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Mahi D 6 years, 1 month ago

Photodiode is fabricated with a transparent window to allow light to fall on the diode.

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ANSWER

Why shape of electric field due to a time varrying magnetic field is circular?

Posted by Tamanna Sharma 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Tamanna Sharma 6 years, 1 month ago

Reason ,why it's circular in shape.

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Arnav Kandari 6 years, 1 month ago

What do you want??

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ANSWER

Why entire charge given to the conductor resides on the surface? What is the fundamental reason behind that.

Posted by Tamanna Sharma 6 years, 1 month ago

CBSE > Class 12 > Physics

3 answers

Tamanna Sharma 6 years, 1 month ago

But there is no condition mention in electrostatics that if field is zero then there must be nocharge is present there.

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Adi Kumar 6 years, 1 month ago

As there no electic field inside conductor so no charge would be inside the conductor.

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Adi Kumar 6 years, 1 month ago

When we apply an electric field on a conductor, an electric field is induced inside the conductor for a small time . As we know free electrons are present inside conductor. So the induced electric field moves the free electrons to the side of conductor increasing electron density on one side of conductor. As a result an opposite charge is developed on other side of conducter. Asa a result an electric field opposite to the direction of applied field is generated , so both cancel out each other.and electric field inside the conducter is zero .

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ANSWER

Can anyone give Full explanation of zener diode And photo diode

Posted by Hemanshu Sharma 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Riya Rana 6 years, 1 month ago

Photodiode is also operated in reverse biasing because we can easily observe the changes in current with change in voltage. Photo diode conducts current when a light of suitable frequency is incident on it, which breaks various covalent bonds.

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Riya Rana 6 years, 1 month ago

Zener diode is operated in reverse biased and is highly doped and is also known as a voltage regulator because it passes passes heavy current and high voltage when the incoming voltage fluctuates above the breakdown voltage.

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ANSWER

I wanna ask one thing, ki is app mein cbse ke saare last years papers mentioned h???

Posted by Meghna Sharma 6 years, 1 month ago

CBSE > Class 12 > Physics

5 answers

Apoorva Rao 6 years, 1 month ago

Yes

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Riya Rana 6 years, 1 month ago

Yess

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Meghna Sharma 6 years, 1 month ago

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Meghna Sharma 6 years, 1 month ago

Sure

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Jauhar Ali 6 years, 1 month ago

Yeh

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ANSWER

Interference of light in this resultant displacement equation?????

Posted by Shivangi Mishra 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Prashant Mishra 6 years, 1 month ago

Hello welll..... Y=[A1^2+A2^2+2.A1.A2cos(£)]^1/2 £=|(w1-w2)t+(k1-k2)x+(€1-€2)|

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ANSWER

Two circular coils X and Y having radii R and R/2 respectively are placed in horizontal plane with their centers coinciding with each other. Coil X has a current I flowing through it in clockwise sense . What must be the current in coil Y to make the total magnetic field at common centre of the two coils zero?

Posted by Simran Dangi 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Prashant Mishra 6 years, 1 month ago

2I in opposite sense》anticlockwise

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ANSWER

Magnetic energy density of inductor

Posted by Rajdeep Prajapati 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Prashant Mishra 6 years, 1 month ago

Bsquare by 2 mu

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Prashant Mishra 6 years, 1 month ago

B^2/2ų

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ANSWER

Remove the lock

Posted by Prachi Dwivedi 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Aditya Chauhan 6 years, 1 month ago

What??

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Riya Rana 6 years, 1 month ago

Oky

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ANSWER

if i will just do last year questions how much marks will i get??

Posted by Sachi Pandey 6 years, 1 month ago

CBSE > Class 12 > Physics

4 answers

Uday Mann 6 years, 1 month ago

10 year =?

1Thank You

Ankita Rao 6 years, 1 month ago

Tbh, the more u solve, the more it'll help u for the 3 and 5 markers... For 2 and 1 markers and also for the pattern (overall) try to solve all the sample question for 2020; it'll benefit u more... :) As for marks, u can easily score 45-55

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Prashant Mishra 6 years, 1 month ago

Above than 75

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Rajdeep Prajapati 6 years, 1 month ago

Less than 30

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ANSWER

An electric heater is connected turn by turn to A.C. current and D.C. current. Which will produce more heat?

Posted by Gurbhej Singh 6 years, 1 month ago

CBSE > Class 12 > Physics

4 answers

Tamanna Sharma 6 years, 1 month ago

I think its ac because ( less heat loss in power supplier ~ more voltage~ adjustable with the help of transformer acc to need ~produce eddy current (do not reduce it )for more heating purpose in the coil of heater. May be, this will be the reason.

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Prashant Mishra 6 years, 1 month ago

Else can be think

0Thank You

Prashant Mishra 6 years, 1 month ago

Always we measure rms value of an A.C. for comparison with D.C..... iofdc=irms ofac then same heat is produce

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Muskaan Vig 6 years, 1 month ago

D.C. current will produce more heat.

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ANSWER

If. We want to find out the motion of a dipole in uniform electric field. What will we do?

Posted by Khushi Rawat 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Prashant Mishra 6 years, 1 month ago

As the name dipole 》both pole at same so the net force on the system of charge is zero 》on the centre of mass 》by newton's first law 》no force ....no change in state of motion 》if you throw a dipole its velocity of centre of mass remains same 《no other forces are acting

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Rajdeep Prajapati 6 years, 1 month ago

Its my WhatsApp no meassge me i will send you proof

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ANSWER

Is transistor in syllabus?

Posted by Anubhav Shukla 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Hemanshu Sharma 6 years, 1 month ago

No and also logic gates not in our syllabus

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Tamanna Sharma 6 years, 1 month ago

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ANSWER

Is anyone having blueprint of all the subjects

Posted by S S 6 years, 1 month ago

CBSE > Class 12 > Physics

4 answers

Meghna Sharma 6 years, 1 month ago

Me too want

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S S 6 years, 1 month ago

Can u pls give the website from u got the official blueprint

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S S 6 years, 1 month ago

Official?

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Shivam Jain Jain 6 years, 1 month ago

Yes

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ANSWER

Why are element dopant for silicon or germanium usually chosen from group xlll or group xv?

Posted by Abhishek Sah 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Mahi D 6 years, 1 month ago

Dopant for silicon are taken from grp 13 and 15 because their atomin sizes are not very different from that of grp14 .. so this will not distort the structure of the semiconductor . If elements of other groups are used ,it would not be feasible to make it and it will not behave like a semiconductor.

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Tamanna Sharma 6 years, 1 month ago

In order to make ptype and ntype semiconductor means to create donor site and acceptor site in the valance shell, reason -the basic reason to use these groups is the dopant energy level within the bandgap ,for a particular temperature these dopant 100% activate according to the relation : K/t =1/V×eta here K is boltzman constant , t is temperature in Kelvin, V is thermal voltage, eta is ideality factor. But why at high diode current eta is 1 for both Ge and Si ,that's also my query if you know about this ,then please tell me.

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ANSWER

Why is wave theory of electromagnetic radiation not able to explain photoelectric effect? How does photo picture resolve this problem?

Posted by Abhishek Sah 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 6 years, 1 month ago

1 : Wave picture of light doesn't have any concept of threshold frequency. 2. Time lag : electron require some time to collect energy needed in order to come out from the metal surface, it is against the experimental observation in which the emission of photo electrons starts instantaneously

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ANSWER

Define dielectric constant of a medium in terms of capacitance of a capacitor. Please define it in simple words.

Posted by Tamanna Sharma 6 years, 1 month ago

CBSE > Class 12 > Physics

2 answers

Mahi D 6 years, 1 month ago

It means K=C (dielectric)/ C(free space)

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Mahi D 6 years, 1 month ago

Dielectric constant of a medium is defined as the ratio of the capacitance of a capacitor with the dielectric as the medium to its capacitance with vacuum between its plates.

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ANSWER

Bhors model of hydrogen atom derivations

Posted by Ruchi Sahu 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 6 years, 1 month ago

You can see it with animation with better understanding from YouTube channel "professor dave explain "(4:50)min duration l hope this will help you.

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ANSWER

Write the principle of potentiometer obtain the expression for the study of the internal resistance

Posted by Muskan Sejwar 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Riya Rana 6 years, 1 month ago

At constant current flowing through a wire of constant area of cross section the potential drop across the wire is directly proportional to the length of the given wire. Hence, V=kL........and r=R(L1 / L2 -1)

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ANSWER

What is fringing effect

Posted by Aditya Singh 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 6 years, 1 month ago

In the capacitor the gap between the parallel plates the field lines are parallel but at the corners horizontal components cancel out and vertical components add up,in order to pull the dielectric slab into it ,due to this the parallel field lines at corner ( top and bottom) becomes curved, known as fringing effect.

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ANSWER

Prove that the ideal capacitor in an ac circuit does not dissipate power

Posted by S S 6 years, 1 month ago

CBSE > Class 12 > Physics

1 answers

Tamanna Sharma 6 years, 1 month ago

P= VIcos● ,here cos●=R/Z, for an ideal capacitor R=0 hence P = VI ×0 =0 , hence power dissipated is zero. Conceptually kabhi source capacitor ko energy transfer kar raha he or vice versa, then average power is zero

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ANSWER

Give me some guidelines to score more marks in physics

Posted by Jai Ram 6 years, 1 month ago

CBSE > Class 12 > Physics