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Class 12th

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5 months ago

Class 12th Physics

Due to cold weather a 1m water pipe of cross-sectional area 1 cm2 is filled with ice at -10°C. Resistivity heating is used to melt the ice. Current of 0.5A is passed through 4 k Ω  resistance. Assuming that all the heat produced is used for melting, what is the minimum time required?

(Given latent heat of fusion for water/ice = 3.33 * 105 J kg-1, specific heat of ice = 2 * 103 J kg-1 and density of ice = 103 kg/m3)
0 Follower 6 Views

A
alok kumar singh

Contributor-Level 10

Energy required to melt

Q = M S Δ T + M L  

⇒ 1 0 − 1 * 2 * 1 0 3 * 1 0 + 1 0 − 1 * 3 . 3 3 * 1 0 5      

->3.53 * 104 J

Heat produce in wire

H = l2RT

  Q = 3 . 5 3 * 1 0 4 = ( 1 2 ) 2 * ( 4 * 1 0 3 ) * t

t = 3 . 5 3 * 1 0 4 * 4 4 * 1 0 3 = 3 5 . 3 s e c             

             

New answer posted

5 months ago

Class 12th NCERT

How useful are the Shiksh's NCERT notes for exam preparation?
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N
Nishtha Datta

Beginner-Level 5

Shiksha's NCERT notes are extremely useful for efficient preparation. We offer structured chapter-wise notes for the latest CBSE  syllabus and provide concise summaries and key formulas. These notes are designed for quick and last-minute revision. These short revision notes offer step-by-step explanations for conceptual clarity and include important questions from previous years' papers and NCERT Textbooks. Our notes are equally beneficial for competitive exams like JEE Mains, NEET and other exams as well.

New answer posted

5 months ago

Class 12th English

Directions for questions: Read the following passage and solve the questions based on it.

I. A resort has 6 rooms – 101, 201, 301, 401, 501 and 601. Rooms '101' and '301' can accommodate two persons each; the rest can accommodate only one person each.

II. Eight persons Arjun, Pari, Ishan, Krish, Niti, Moksh, Nitin and Jyoti are to live in these rooms. Pari, Niti and Jyoti are females while the rest are males. Persons of different genders can't be put together in the same room.

III. No man is willing to live in room 301 or 601.

IV. Arjun wants to live alone but doesn't want to live in room 201 or 401.

V. Krish needs a partner but is n

...more
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P
Payal Gupta

Contributor-Level 10

Room

Person

101

Krish, Ishan

201

Moksh/Nitin

301

Pari, Niti

401

Nitin/Moksh

501

Arjun

601

Jyoti

New answer posted

5 months ago

Class 12th Atoms

A free electron of 2.6 eV energy collides with a H+ ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon. (h = 6.6 * 10-34 Js)
0 Follower 6 Views

V
Vishal Baghel

Contributor-Level 10

Energy of electron in first existed state will be -3.4 eV.

So total energy difference will be (2.6 + 3.4) eV.

Wavelength ( λ ) = 1 2 4 2 e V − n m 6 e V = 2 0 7 n m

F r e q u e n c y = c λ = 3 * 1 0 8 2 0 7 * 1 0 − 9 = 1 . 4 5 * 1 0 9 M H z

 

New answer posted

5 months ago

Class 12th NCERT Notes

How can I get full marks in the Class 12 Maths exam?
0 Follower 8 Views

N
nitesh singh

Contributor-Level 10

All students work hard to get a full score. Here are a few tips that can make your dream come true.

  • Master the concepts from the NCERT textbook before using any other notes and mark importnt points.
  •  Consistentantly practice problems, highlight important formulas and theorems, and creating a personalized formula sheet.
  • Regular- daily and weekly revision of the important concepts and formulas.
  • Solve all examples and practice questions given in NCERT Textbooks.

New answer posted

5 months ago

Class 12th Dual Nature of Radiation and Matter

The temperature of an ideal gas in 3-dimensions is 300K. The corresponding de-Broglie wavelength of the electron approximately at 300 K, is:

[me = mass of electron = 9 * 10-31kg

h = Planck constant = 6.6 * 10-34 Js

kB = Boltzmann constant = 1.38 * 10-23 JK-1]
0 Follower 6 Views

A
alok kumar singh

Contributor-Level 10

De Broglie wavelength

λ = h m V = h 2 m E E → K . E .              

E = 3 2  KT for gas

S o λ = h 3 m K T = 6 . 6 * 1 0 − 3 4 3 * 9 * 1 0 − 3 1 * 1 . 3 8 * 1 0 − 2 3 * 3 0 0

λ = 6 . 2 6 * 1 0 − 9 m λ = 6 . 2 6 n m                

             

New answer posted

5 months ago

Class 12th English

Directions for questions: A famous retail electronics showroom chain has six new mobile phone models – A, B, C, D, E and F – each equipped with at least one of the following three options: digital camera, music player, and office document viewer. No mobile has other option. The following condition apply: B features both a digital camera and an office document viewer. C has digital camera and music player. C and E have no options in common. D has more options as compared to C. B and F have exactly one option in common. A has fewer options as compared to F.

For exactly how many of the six mobile phones is it possible to determine exa

...more
0 Follower 11 Views

P
Payal Gupta

Contributor-Level 10

Here, DC = Digital Camera; ODV = Office Document Viewer; MP = Music Player

Number of options

Mobile

Options

1

A

DC/ODV/MP

2

B

DC, ODV

2

C

DC, MP

3

D

DC, MP, ODV

1

E

ODV

2

F

DC, MP/MP, ODV

New answer posted

5 months ago

Class 12th English

Seven Trainers A, B, C, D, E, F and G – teach management courses at a ABC institute in west Delhi. Each instructor teaches during exactly one term: the first term, the second term, or the third term. The following conditions apply: B teaches during the third term. C and D teach during the same term. G teaches during either the first term or the second term. Exactly twice as many Trainers teach during the third term as teach during the first term. E and G teach during different terms. A and F teach during different terms.

Each of the following contains a list of Trainers who can all teach during the same term EXCEPT
0 Follower 2 Views

P
Payal Gupta

Contributor-Level 10

B, F, G can be two only, which leaves J and N same which is not possible.

New answer posted

5 months ago

Class 12th English

Seven Trainers A, B, C, D, E, F and G – teach management courses at a ABC institute in west Delhi. Each instructor teaches during exactly one term: the first term, the second term, or the third term. The following conditions apply: B teaches during the third term. C and D teach during the same term. G teaches during either the first term or the second term. Exactly twice as many Trainers teach during the third term as teach during the first term. E and G teach during different terms. A and F teach during different terms.

If exactly one instructor teaches during the second term, which one of the following must be true?
0 Follower 1 View

P
Payal Gupta

Contributor-Level 10

If D = 3 and C = 3

There are two teachers for first term and four for third term.

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