Life without light would have been pretty dull. Light travels at a speed of 186,000 miles per second. You must have observed that in your house that whenever a beam of light enters a dark room through a tiny hole in the window, the lightwave always travels in a straight line.

Let us carry out a small activity to show that lightwave travels along a straight line. Take three CD’s and align them together. Align them in such a way that all the CD’s line in a straight line. Now take a candle and place it at the other end. Do make sure that the tip of the candle and the holes of the CD’s all lie in the straight line. Ensure that the height of the CD’s and the tip of the candle are same. Observe the flame of the candle. We are able to see the flame of the candle because the light wave travels through the holes and reaches our eye.

Now if suppose we displace the center of the CD’s we observe that we are not able to see the flame of the candle. Why does that happen? This is because the light gets blocked. If the light could have the ability to take a curve and travel, we could have seen the lightwave. But since light travels in a straight line, we were unable to see the flame of the candle when the CD is displaced. This proves that light travels along a straight line

In the above picture, we can clearly see that light coming through the holes in the window travel along a straight line

The copying of DNA during reproduction is important because:

• The replication of DNA ensures that each daughter cell formed at the end of cell division, receives equal amount of DNA.
• If DNA won't be copied then the daughter cells won't receive all necessary genes.
• There may be absence of important proteins which are encoded by DNA, if DNA won't be replicated.
• Copying of DNA may result in recombination which will lead to evolution.
• Transfer of genetic material from one generation to other makes the organisms to have similar functions.
• Stability of population is maintained.

The amount of current flowing through the electrical component is reduced by half.

Explanation:

According to Ohm’s law

V = IR

where

V= potential difference

I= Current

R = Resistance

By modifying the equation

I=V/R ——- (i)

potential difference across the two ends of the component decreases to half

therefore, the new potential difference be Vʹ=V/2

Resistance remains constant across the electrical component

new current is drawn by the electrical component is Iʹ = Vʹ/R

= (V/2)/R        {Substituting Vʹ=V/2 in the above equation}

= (1/2) (V/R)

= (1/2) I = I/2

Hence the amount of current flowing through the electrical component is reduced by half.

National Democratic Alliance (NDA)  is a group of other parties headed by BJP who has clear majority in Parliament. NDA came to Power in 2014.

United Progressive Alliance  is group of Parties headed by Congress who have only 44 MPs in the Lok Sabha. As per Rules since their No is less that 10% of the total seats they cannot be termed as Main Opposition party and have it’s MP as the leader of Opposition. Their MP is now the leader of Opposition but I am not sure how, why and under what circumstances that post was conferred on him.There have been two versions of UPA 1 and UPA 2. They ruled the country for 10 years under Dr Manmohan Singh as the PM. During this 10 years, Lalu Prasad Yadav’s party RJD was one of the allies of UPA 1 and UPA 2. He enjoyed Cabinet position while fodder scam case was pending trial against him in the Court of Law. The charges against him were of corruption and misappropriation of Public Funds etc. He has been now convicted in two cases out of 6 and is presently lodged in Jail. The case against him was pending for framing of charges for about 25 years. Framing of charges means the court frames charges against the accused based on the evidence available on record. The accused is asked if he pleads guilty and if he pleads not guilty the charges are framed. This is the stage when the trial commences. Till then the case pending is called Court proceedings. It is by and large common for a case pending trial for few years. But pending for framing charges for 25 years is shocking and surprising. This cannot happen in a normal case. So readers have to read between the lines. The trial ended in logical conclusion only after NDA came to Power.

It is on record that there were 54 scams during Congress regimes from 1947 till 2014. And NDA has the first PNB Scam. What a track record.

Petiole: Petiole is the long, thin, stalk that links the leaf blade to the stem.

CBSE Class 10 Science Revision Notes Chapter 15 Our Environment

• Environment means everything which surrounds us. It may include living (biotic) and non-living (abiotic) components.
• Biotic : Plants and animals. Abiotic : Air, water etc.
• Environment affect the life and development of an organism in its natural habitat & vice a versa.
• Substances that can be decomposed by the action of micro-organism like bacteria are called bio-degredable. E.g. organic wastes.
• Substances which cannot be decomposed by the action of microorganisms are called non-biodegradable.
• Example of biodegradable wastes : cattle dung, cotton, jute, paper, fruit and vegetable peels, leaves etc.
• Examples of non-biodegradable wastes : plastics, polythene bags, synthetic fibres, metals, radioactive wastes.

For more click on the given link:

<a href="https://mycbseguide.com/blog/our-environment-class-10-notes/">https://mycbseguide.com/blog/our-environment-class-10-notes/</a>

Reported areas or reporting areas refer to the area which has been surveyed and which provide a detailed account , information about the land use pattern that  ​reflects the usage of land for purposes like forests, for cultivation which is shown in net sown areas, area that is uncultivated, it also includes fallow land, land not available for cultivation. 

In India, the reporting area which has been surveyed and form part of the land use data is 93%. This is because of the following reasons:

a. Many of the north east states except for Assam have not been reported and covered in the data, because of lack of road connectivity to some extemely remote areas, instability in the region, external issue with regard to the state of Arunachal with China.
b. Similarly, parts of Jammu and Kashmir which are occupied by Pakistan and China have not been reported .

Metternich described Italian revolutionary Giuseppe Mazzini as 'the most dangerous enemy of our social order' because he was against conservatives and ran two secret socities.

Explanation:

• Matternich who proposed Congress of Vienna  was against the modern and vigorous views propounded by Mazzini.

• Matternich was conservative in ideology and did not appreciate the change which Mazzini was trying to infuse in the society through his revolutionary society such as Young Europe and Carbonari Young Italy.

• Mazzini was the Italian revolutionary who was modern and pursuer at the age of twenty four in 1831.

• He established various secret organizations in Germany, France, Switzerland and Poland.

• Thus, the disagreement between the views of Matternich and Mazzini led to the popular view of Mazzini being dangerous to the established social order of Europe.

The two secret societies founded by ‘Giuseppe Mazzini’ were young Europe and Young Italy.

Giuseppe Mazzini was an ‘Italian revolutionary’ who founded two ‘underground societies’. He formed ‘Young Italy’ in Marseilles and thereafter he formed ‘Young Europe’ in Berne. Giuseppe Mazzini played an ‘important role’ in supporting the ideas for the unification of Italy.  

He wanted to involve the youth in revolutionary activities so he founded the underground secret societies Youth Italy and Young Europe. He played an ‘important role’ in liberal nationalism.   

Napoleon was defeated in 1815 by the combined power of Britain, Russia, Prussia and Austria. After the defeat of Napoleon, European governments wanted to follow conservatism. The conservatives believed that established, traditional institutions of state and society should be preserved. They believed in preserving the monarchy, the Church, social hierarchies, property and the family. But most of them also wanted to retain the modernization which Napoleon carried out in the spheres of administration. The conservatives believed that modernization would strengthen traditional institutions. It was believed that a modern army, an efficient bureaucracy, a dynamic economy, the abolition of feudalism and serfdom could strengthen the monarchies of Europe.

Hyphae are thread like structure. tiny blob on a stick structure are sporangium and it contains spores.when this structure come in contact with other moist surface the begin to grow

Congress of Vienna was hosted by Austrian Chancellor Duke Metternich in 1815. 

The following changes were made: 

(i) The Bourbon dynasty, which had been deposed during the French Revolution, was restored to power and France lost the territories it had annexed.

(ii) A series of states were set up on the boundaries of France to prevent the French expansion in future. Thus, the kingdom of the Netherlands, which included Belgium, was set up in the North and Genoa was added to Piedmont in the South.

(iii) Prussia was given important new territories on its. Western frontiers, while Austria was given control of Northern Italy. 

(iv) The German confederation of 39 states that had been set up by Napoleon was left untouched.

The Provisions of Treaty of Vienna of 1815 include:
(i) The Bourbon dynasty was restored to power.
(ii) France lost the territories it had annexed under Napoleon.
(iii) A series of states were set up on the boundaries of France to prevent French expansion in future.
(iv) Belgium was set up in the north and Genoa was added to Piedmont in the south.
(v) Prussia was given important new territories on its western frontiers, while Austria was given control of northern Italy.
(vi) In the east, Russia was given part of Poland while Prussia was given a portion of Saxony.
(vii) Thus, monarchies that had been overthrown by Napoleon were restored and a new conservative order was created in Europe.

Given quadratic polynomial,
x² - (k+6)x + 2(2k+1) = 0

By comparing it with ax²+bx+c = 0,we get
a = 1 , b = -(k+6) , c = 2(2k+1)

Sum of zeroes = -b/a
= -[-(k+6)]/1
= k+6

Product of zeroes = c/a
= 2(2k+1)/1
= 2(2k+1)

As per problem,
Sum of zeroes = ½ × product of zeroes
k+6 = ½ × 2(2k+1)
k+6 = 2k+1
2k-k = 6-1
k = 5

Conservatism is a political philosophy that stressed the importance of tradition, established institutions and customs. It also laid stress on gradual development as opposed to revolutionary change. Following are some of the salient points of conservatism:

1.  i. Conservatives believe that traditional institutions like the church, social hierarchies, property and the family should be preserved against all forces of change.
2.  ii. Many conservatives even saw forces of modernism strengthening traditional institutions like monarchy.
3.  iii. Around 1815, the conservative regimes in Europe were largely autocratic. They did not tolerate democratic thought, political criticism or dissent. They often put restrictions on activities that questioned the legitimacy of autocracy and imposed censorship laws on newspapers, books, plays and songs that promoted ideas of liberty and freedom.

Coalition government is a cabinet of a parliamentary government in which multiple political parties cooperate, reducing the dominance of any one party within that "coalition". The usual reason for this arrangement is that no party on its own can achieve a majority in the parliament.