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Dec 3, 2016

5. Law of Refraction Of Light Physics Class 10

plane-concept

There are two laws of refraction of light. these are :
a) Incident say , refracted ray and normal lie on same plane .
The concept of plane is shown in the image. In terms of x,y and z co-ordinate system , the y-z plane is shown in light sky blue colour. We write on our copy which is considered x-y plane. The image is given just for understanding of plane concept. It is not needed while writing the law. Try to image other planes in the image.



b) Ratio of sin of angle of incidence and sine of angle of refraction remains constant for a pair of media. i.e.

Law of Refraction Of Light Physics Class 10

sin i / sin r = constant (n)
this constant is called refractive index of medium 2 with respect to medium 1.
or we can write
n2 / n 1 = sin i / sin r
Where n 1 is the refractive index of first medium here air. And n2 is the refractive index of second medium here glass.
∴ n2 = n1 x ( sin i / sin r )

If you have any query regarding the laws of refraction then comment below.

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Nov 24, 2016

4. Effects of Refraction of Light Physics Class 10

Effects of Refraction of Light Physics Class 10

There are many effects of the refraction of life in our day to day life. For example I am citing few of them.
a) The partly immersed stick appear to be bend at the surface of the water.
b) The coin kept in water appears raised upward.
c)The water of a pool appear less depth.
d)Stars appear to twinkle in the sky when the sky remains clear.
e)A lemon immersed in water appears to be bigger in size.
All these are discussed in the above video. If you have any confusion then comment below.

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Nov 6, 2016

3 Three Cases of Refraction of Light Physics Class 10

three cases of refraction of light

Case1: When ray of light travels from rarer medium like air to a denser medium like glass then it bends towards normal.

Case 2: When ray of light travels from denser medium like glass to a rarer medium like air then it bends away from the normal.

Case 3: When ray of light travels from rarer medium like air to a denser medium like glass and again emerges to the previous rarer medium then it suffers a lateral displacement as shown in the figure.

emergent ray
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Oct 28, 2016

Keeping Pressure On children for Achieving high Ambition is Right or Wrong उच्चे लक्ष्य को पाने के लिए माता पिता द्वारा बच्चों पर डाला जाने वाला दबाव उचित है या अनुचित है।

लक्ष्य की उंचाई सफलता को गति और उर्जा प्रदान करती है। परन्तु ऐसा लक्ष्य जो किसी बच्चे की क्षमता से अत्यधिक है । वह बच्चे को मानसिक रोगी या पागल बनाता है । और कभी कभी बच्चे आत्महत्या का शिकार हो जाते हैं। इसलिए मेरा मानना है कि इस तरह का दबाव अनुचित है। जब जीवन ही नहीं रहेगा तो जीवन में लक्ष्य का कोई मतलब नहीं है।

जब लक्ष्य बच्चे की क्षमता की परिधि के बाहर होता है , तो वह लक्ष्य उसके लिए बोझ बन जाता है । चुंकि बच्चे अपने माता पिता को खुश देखना चाहते हैं, इसलिए वे झूठ बोलने लगते हैं। जैसे मैने याद कर लिया, होमवर्क कर लिया , मै नकल नहीं करता हूं , मै 90% से जादा अंक प्राप्त करूंगा इत्यादि। इस दबाव में वे अपने अन्दर छुपी मेधा को पररव नहीं पाते । और माता पिता के सोंच के ढांचे में फंस जाते हैं। और नौकरी की खोज में दर दर भटकते रहते हैं। आज के इस प्रतिस्पर्धा के कारण दूसरेआम बच्चे थोड़ा तकनीकी सीखकर रोजी रोटी की दौड़ में इस बच्चे से आगे निकल जाते हैं। और सबसे बड़ी बात यह है कि वे निम्न और कमजोर मानसिकता के शिकार नहीं बनते। मेरे अनुसार ऊंचे लक्ष्य को अपने बच्चे की क्षमता के अनुसार निश्चित करना चाहिए और दबाव न डालकर बच्चों की सहायता करनी चाहिए। उनसे कनेक्ट होना चाहिए। यही मन्त्र उनके जीवन को सफल बना सकता है।

Keeping Pressure On children for Achieving high Ambition is Right or Wrong

माता पिता को मानसिक दबाव न देकर बच्चे से उसके समस्याओं के बारे में बात करने का प्रयास करना चाहिए । ताकि वह समझ सके कि आखिर उनका बच्चा क्यों नहीं अच्छे अंक प्राप्त नहीं कर पा है। ऐसा करने से बच्चे की कमजोरी का पता चल जाता है। जिसपर प्रयास कर के ठीक किया जा सकता है। पढ़ाई की क्रिया के समीप ऐसी बहुत सी बातें होती है, जो बच्चों को सिखाना पड़ता है। जैसे अनुशासन, खुश रहना , स्वस्थ रहने की कला, सामाजिकता पढ़ना -सुनना -लिखने के वृत्त की महत्ता इत्यादि | परीक्षा देने के तरीके सिखाना भी जरूरी है। कुल मिलाकर कहने का तात्पर्य यह है, कि बच्चे के स्थान पर अपने आप को रखकर हमें उसकी परेशानियों को समझना चाहिए। और उसे दूर करने का प्रयास करना चाहिए। अपने बच्चों को अनुशासन उत्साहित करना बहुत महत्वपूर्ण है। इससे वे अपने माता-पिता को सबसे अच्छा मित्र समझने लगते हैं। और अपनी जिम्मेदारी निभाने में अधिक सक्षम बन जाते हैं।

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Oct 19, 2016

2. Causes Of Refraction of Light Physics Class 10

Cause of Refraction : The speed of the light in different transparent substances is different. For example speed of light in air is 3×10⁸ m/s and that of in glass is 2×10⁸ m/s. It is clear that the two speeds of the light are different. When light enters from air to glass the speed of the light gets decreased at the junction of the two media. This change in speed of the light affects the speed the of the various segments of the beam of the light. This can be concluded by the image. This change in speed of the light causes refraction.

Causes Of Refraction of Light Physics Class 10
Therefore the refraction of light is due to the change in the speed of light on going from one medium to another.

Now it is good question why change in speed causes refraction. Here is the answer. If we look the image carefully. The left part of the beam of light enters first into another medium while its right part remains still in first medium here air. Therefore the speed of the left part of the beam experiences speed reduction before that of the right part of the beam. This causes less distance covered by left side beam and more distance traveled by right side beam.

Dear friend if you have any doubt , then comment please. Or you can give your suggestion about this part of the refraction of light.

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Oct 15, 2016

1 Refraction of Light Definition and Introduction Physics Class 10

Refract means bending. The bending of ray of light when it pass from one medium to another medium is known by a term called refraction.

Refraction of Light Definition and Introduction Physics Class 10

Refraction of Light happens due to different speed of light in different medium. Speed of light in air is 3x10⁸m/s and that of in glass is 2x10⁸m/s.

Refraction of Light: It can be defined as the change in the direction of light when it passes from one medium to another medium obliquely.


A transparent substance in which light can travel is called a medium. For example Air, water, glass, kerosene etc are the transparent substances in which light can travel.

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Oct 7, 2016

5.Heating Effect of Electric Current Physics Class 10

heating effect of electric current physics

Current flowing through a conductor produces heat. This heat depends on quantity of current flowing through the conductor, time and resistance of the conductor. We can write:
H α I²
H α R
H α t
By combining these three relation we get:
H α I²Rt
K= (H/(I²Rt))
K= H
for I=1 Amp., R= 1 ohm and t= 1 sec.
K becomes equal to heat generated at this condition. It is found heat generated is 0.24 calorie.
∴ H=0.24 I²Rt

This is also known as Jouls Law of Heating.

Also remember. 1 Calorie = 4.2 Joul

The above video contains explanation of heating effect of current through a conductor. The equation derivation is also shown.

Why 0.24 added while breaking proportionality is clearly explained.

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Important Mathematical Relations of Measurement

mathematical-relationship
Important mathematical relations of measurement.

These are very important mathematical relations. It must be on the tongue of a student . These common relations are seen very frequently in the sum .

| Mass
1 Ton = 10 Quintals 1 Quintal = 100 Kg
1 Kg = 1000 g 1 pound = 453 g
Distance
1 Km = 1000 m 1m = 100 cm
1 feet = 12 inches 1 inch = 2.54 cm
1 yard = 3 feet
Time
1 year = 365 days 1 month = 30 days
1 week = 7 days 1 hour = 60 min
1 min = 60 seconds 1 day = 24 hours
Countable
1 gross = 144 1 dozan = 12
Re 1 = 100 Paise
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Oct 4, 2016

Important Squares And Square Root Lower Grade Students Mathematics

Important Squares and their square root.
THE STUDENT MUST MEMORISE THIS BY TONGUE.


42 = 16 112 = 121
52 = 25 √(25)=5
62 = 36 √(36)= 6
72 = 49 √(49 ) = 7
82 = 64 √(64)= 8
92 = 81 √(81)= 9
102 = 100 √(100) = 10
112 = 121 √(121) = 11
122 = 144 √(144 ) = 12
132 = 169 √(169 ) = 13
142 = 196 √(196 ) = 14
152 = 225 √(225 ) = 15
162 = 256 √(256 ) = 16
172 = 289 √(289 ) = 17
202 = 400 √(400 ) = 20
252 = 625 √(625 ) = 25
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Oct 2, 2016

In Time of Adversity Question Answer Class 8

This chapter is about a letter written by a young lady; whose father was victim of this terror attack.

Q(01) Where was the writer's father when the terrorist attack took place? Who was with him?

Ans: The writer's father was at the Indian restaurant on the first floor of the Oberoi hotel when the terrorist attack took place. His two best friends were with him .They were having dinner together.

Q(02) How did the writer's father save himself? What were the qualities that helped him to protect?

Ans: The terrorist rounded up the hostages and made them to climb the service staircase, the eighteenth floor. On reaching the eighteenth floor landing ,they made the people line up against the wall then they opened fire on the people simultaneously . Her father was at the center of the line and body as soon as the firing began . He protected himself out of reflex or his presence of mind .    

Q(03)What did the writer's father and other survivors do to keep themselves alive till help arrived?

Ans:  When the terrorist left the landing after setting up explosive , the lady's father along with the three other survivors, climbed up the rest of the stairwell and discovered a large HVAC Plant room in which they decided to take shelter . They spent the rest of seige hiding in that room trying to get the attention of the world outside by waving a makeshift flag out of the window .They drank sips of dirty water from the Air conditioning unit to survive.

Q(04) The terrorists attacked people at every level .Explain this line in the context of the eventful day.?

Ans:  When terrorist attacked people they do not discriminate among them.They killed young kids and even the pregnant woman .They killed middle class workers at the railway station , elite in the hotels, tourist and kids in a cafe and sick and dying in the hospitals.They killed Indians, Americans, Britans and several other nationalities .Men, women, children, policeman,fireman and doctors etc were also killed.

Q(05) Q(05) What are the ideas behind every terror attack that the writer can recognise ? Do you agree with the writer's views? Justify your answer. .........

Ans:  The ideas behind every terror attack is the hatred anger and desperation of the terrorists and the cold-blooded targeted ruthlessness of these who sent them .They respect nothing but their own twisted beliefs to achieve them .They have declared war on every other way of life. Yes , I agree with the writer's views.     

Q(06) Why does the writer want to thank the readers? How have the readers helped the writer ? .

Ans:  Writer wants to thank the reader for the incredible concern and support that the readers have shown for the Mumbai victims when the whole of Mumbai was under terrorist attack. The reader helped the writer through their concern sympathy and prayers for the people of Mumbai who were under attack.     

Reference to the context -
(1) They communicated to each other by tough as they were too afraid to make a sound.

Q(a) Who does 'they' refer to??

Ans: Here 'they' referred to the survivors who survived from the mass murder of the terrorist at the eighteenth floor of the Oberoi hotel.

Q(b) Why were they afraid to make a ?

Ans: They were afraid to make a sound because a small sound in the room might bring back the terrorist would find that there were survivors , they would show no mercy and killed them.    

Q(c).What had happened to them ?

Ans:  The terrorist rounded up all the people of the Oberoi hotel and took them to the eighteenth floor landing. They made the people line up against the wall and opened fire on the people simultaneously.


(2) This was systematic, cold-blooded,slaughter.

Q(a) What is being described here?

Ans:  Here the writer describes a series of synchronized terror attack at various places in Mumbai.

Q(b) Why does the writer say so?

Ans:  The writer said so because terrorist attack people at every level. They did not show mercy to the children and the old.They killed middle-class workers , elite ,tourists and kids .They stormed three hospitals and killed the sick and dying .They did not discriminate among the different nationalities.They killed men, wonen , children, policeman, firemen , doctors.


(3) Over the next week....I hope the rest of the world does too.

Q(a) What is the writer talking about in these lines?

Ans: The writer is talking about the terrorist attack in Mumbai and the victims those who are killed .Writer wants everyone to pray for the souls of the ******.She also request everyone to help the victims who survived .She wants us to help them to come back to their normal life.

Q(b) Why does the writer want the world to do the same ?

Ans: Writers want world to do the same because terrorism is not a problem in any particular country . It is now a global war and people of every country are fighting to combat terrorism . So, it should be a joint fight and we should help one another to solve this global problem.   

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