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

Resistivity is costant and resistance increase 4 time to the original resistance because if the wire is stretched than length is double and area of cross section ki half

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Fardin Islam 7 years ago

Risistivity is constant for any material at a particular temperature so there will be no change in resistivity, however the resistance will change and according to the question it will be 8 times the preVious resistance.

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Ashu Sharma 7 years ago

Doubled

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Why does em waves do not lose momentum while travelling?

Posted by Shivam Chaturvedi 7 years ago

CBSE > Class 12 > Physics

1 answers

Hiwani Agrawal 7 years ago

Beacsue p =mv where mass is mass and v is velocity

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Sir/madam, I have not yet started studying physics. So, how could I get passed? Pls help...

Posted by Rithwij P 7 years ago

CBSE > Class 12 > Physics

1 answers

Sheenu Syed 7 years ago

Bro.. Read NCERT textbook.. It is enough to score gud marks.. And solve ncert text book questions for numerical.. Only..!

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A particle of charge q is moving with a velocity V in the presence of crossed electric field E and magnetic field B . Write the condition under which the particle will continue moving along x axis . How would the trajectory of the particle be affected if the electric field is switched off?

Posted by Shaji Sultan 7 years ago

CBSE > Class 12 > Physics

1 answers

Sayeda Iram Ateeq 7 years ago

.......From, Lorentz force,F=q(v×B)......... ....Hence, F j^=q (v i^ ×B j^)....... The trajectory will be helical in the absence of electric field.

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Why is the shape of wavefront of light emerging out of a convex lens when a point source is placed at its focus 'plane'????

Posted by Smiley Smiley 7 years ago

CBSE > Class 12 > Physics

2 answers

Sonal Sonal 7 years ago

Made like a curve in which toward centre it is close to lens and in the ends it away from lens it never made plane secondary wave front

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Cherish Narula 7 years ago

Plane wavefront

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Derive Electric filed of a charged dipole

Posted by Jitesh Bs Jitesh 7 years ago

CBSE > Class 12 > Physics

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Prove by reasoning that is without performing any calculation that the magnetic field b vector on the axis of a and face of a very long solenoid is half the value in the middle of the solenoid

Posted by Riya S 7 years ago

CBSE > Class 12 > Physics

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Current is passed from a battery having negligible internal resistance through through two resistors 12 kilo ohm and 24 kilo ohm in series an accurate voltmeter of resistance 12 ohm reads 4.8 volt when joined across 24 ohm resistor what is the EMF of the battery and what should the voltmeter read if joint across 12 kilo ohm resistor

Posted by Riya S 7 years ago

CBSE > Class 12 > Physics

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Plz tell me the weightage of numericals

Posted by Deepanshu Yadav 7 years ago

CBSE > Class 12 > Physics

1 answers

Bhavika Gandikota 7 years ago

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For the same value of angle of incident the refraction angle in 3 media a b and c are 15,25,35 in which would the velocity of light be minimum

Posted by Satish Kumar 7 years ago

CBSE > Class 12 > Physics

2 answers

Dharshika As 7 years ago

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Satish Kumar 7 years ago

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A photosensitive surface emits photoelectron when red light falls on it,. Will it emit photoelectron when blue light is incident on it? Give reason

Posted by P A 7 years ago

CBSE > Class 12 > Physics

1 answers

Aayushi Srivastava 7 years ago

yes.. it will emit photoelectron with more energy bcaz E=hv ..where v is the frequency of incident light....and frequency of blue light is more than red

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State and deduce radioactive decay law

Posted by Manish Bishnoi 7 years ago

CBSE > Class 12 > Physics