A battery can be defined as an electrochemical device (consisting of one or more electrochemical cells) which can be charged with an electric current and discharged whenever required. Batteries are usually devices that are made up of multiple electrochemical cells that are connected to external inputs and outputs.

whatsapp is a part of social media .

By definition, we know that the polygon is made up of line segments. Below are the shapes of some polygons that are enclosed by the different number of line segments.

महाराज जनेक द्वारा आयोजित धनुष यज्ञ में जिस धनुष को राम ने तोड़ा, वह परशुराम के गुरु भगवान शिव का धनुष था।

Law of Refraction using Huygens' Principle:
Similarly, we can use a Huygens construction to illustrate the law of refraction.
Here we must take into account a different speed of light in the upper and lower media. If the speed of light in a vacuum is c, we express the speed in the upper medium by the ratio ni​c​, where ni​ is the refractive index. Similarly, the speed of light in the lower medium is nt​c​. The points D, E and F on the incident wavefront arrive at points D, J and I of the plane interface XY at different times. In the absence of the refracting surface, the wavefront GI is formed at the instant ray DF reaches I. During the progress of ray CF from F to I in time t, however , the ray AD has entered the lower medium, where the speed in different. Thus if the distance DG is vi​t, a wavelet of radius vt​t is constructed with center at D. The radius DM can also be expressed as  
DM=v_i​t 
=v_i​(​DG/v_i​)

=(​n₁/n_t​​)DG 

Similarly, a wavelet of radius n₁/n_t​​n₁/n_t​​ JH is drawn centered at J. The new wavefront KI includes a point I on the interface and is tangent to the two wavelets at points M and N. The geometric relationship between the angles i and t, formed by the representative incident ray AD and refracted ray DL, is Snell's law , which may be expressed as ni​sinθi​=ni​sinθi​.

Reflection of a plane wavefront of light at a plane surface

Where MN: Plane mirror,
RA and QC: Incident rays, 
AP: Normal to MN,
AB: Incident wavefront,
i: Angle of incident,
CE: Reflected wavefront,
 r: Angle of reflection

When wavefront AB is incident on the mirror, at first, point A becomes a secondary source and emits secondary waves in the same medium. If T is the time taken by the incident wavefront to travel from B to C, then BC = vT. During this time, the secondary wave originating at A covers the same distance, so that the secondary spherical wavelet has a radius vT at time T.

To construct the reflected wavefront, a hemisphere of radius vT is drawn from point A. Draw a tangent EC to the secondary wavelet.

The arrow AE shows the direction of propagation of the reflected wave.

AP is the normal to MN at A,

∠RAP = i = angle of incidence and

∠PAE = r = angle of reflection

In Δ ABC and Δ AEC,

AE = BC and ∠ABC = ∠AEC = 90°

∴ Δ ABC and Δ AEC are congruent.

∴ ∠ACE = ∠BAC = i        .....(1)

 Also, as AE is perpendicular to CE and AP is perpendicular to AC,

∠ACE = ∠PAE = r       .....(2)

∴ From Eqs (1) and (2),

i = r

Thus, the angle of incidence is equal to the angle of reflection. This is the first law of reflection. Also, it can be seen from the figure that the incident ray and reflected ray lie on the opposite sides of the normal to the reflecting surface at the point of incidence and all of them lie in the same plane. This is the second law of reflection. Thus, the laws of reflection of light can be deduced by Huygens' construction of a plane wavefront.

Answer:
Frequent pregnancies by women are avoided due to the following reasons:

• It has adverse effect on the health of women.
• It increases the rate of the population of our country.

Major contraceptive methods are categorized as barrier methods, surgical and chemical methods. 

Barrier methods are the physical devices that prevent contraception by inhibiting the entry of sperms in the female genital tract. Example: condoms, diaphragms, cervical caps, etc. 

Surgical methods include vasectomy (blocks vas deferens to prevent sperms from coming out) and tubectomy (blocks fallopian tubes to prevent the entry of eggs in it) in males and females respectively. 

Chemical methods of contraception include any hormonal preparation that serves to alter the hormonal balance of the body to prevent egg maturation or fertilization. For example, oral and vaginal pills. 

Other methods include intrauterine devices (inserted by a physician into the uterus to prevent implantation), medical termination of pregnancy, coitus interruptus, etc. 

p(x) = x²-5x-6
-b/a = 5
c/a = -6

p(6) = 0

Let the other zero be "a"

sum of zeros = 6 + a = -b/a 

6 + a = 5

a = 5 - 6
   = -1

The other zero is -1

Answer:- The ability to move objects like text, Graphics, logos, charts etc, in any direction of the slide is called animation.

Animation is quite beneficial when you wish to focus on important points , it also controls the order of flow of information and helps in increasing the interest of audience.

गोपियों के दृष्टि में योग उस कड़वी ककड़ी के सामान है जिसे निगलना बड़ा ही मुश्किल है। सूरदास जी गोपियों के माध्यम से आगे कहते हैं कि उनके विचार में योग एक ऐसा रोग है जिसे उन्होंने न पहले कभी देखा, न कभी सुना। 

गोपियों के दृष्टि में योग उस कड़वी ककड़ी के सामान है जिसे निगलना बड़ा ही मुश्किल है। सूरदास जी गोपियों के माध्यम से आगे कहते हैं कि उनके विचार में योग एक ऐसा रोग है जिसे उन्होंने न पहले कभी देखा, न कभी सुना। 

Photosynthesis is the process in which green plants use sunlight to make their own food. Photosynthesis is necessary for life on Earth. Without it there would be no green plants, and without green plants there would be no animals.

Photosynthesis requires sunlight, chlorophyll, water, and carbon dioxide gas. Chlorophyll is a substance in all green plants, especially in the leaves. Plants take in water from the soil and carbon dioxide from the air.

Ans. Hari Singh was an experienced thief. He found Anil, a wrestler an easy-going, kind and simple man,
the correct person for his purpose. He found him an easy target to win confidence.

• Delhi first became a capital and an important centre for business during the Tomars and the Chauhans, between the years 1100 and 1200.
• After 1200, Delhi was ruled by Sultans who were originally invaders and rulers from Persia and Central Asia.

•  Subsidies bring about equity between rich and poor farmers by enabling the poor farmers to use modern technology and inputs. On the other hand, some economists believe that once subsidies should be phased out since their purpose has been served and the technology is now widely adopted due to its profitability. They argue that there is no case for continuing with subsidies as It does not benefit the target group and it is a huge burden on the government's finances. They give the following arguments against subsidies in agriculture (i) Subsidies are benefiting the fertilizer industry more than farmers and it is not making any efforts towards increasing its efficiency as it is protected from market competition by subsidies. (ii) Subsidies are mainly being availed by big farmers in affluent regions who do not actually need them. Hence, based on the above arguments, we can conclude that although subsidies are very useful and necessary for poor farmers and to overcome uncertainties associated with farming. It may lead to wastage of resources and thus put an excessive burden on the scarce government finances. Thus, suitable reforms need to be undertaken in order to ensure allocation of subsidies in a targeted manner only to the needy farmers.

d. All of these

Detailed explanation:

Different forms of power-sharing in modern democracies are:

(i) Power-sharing in different forms of government: Power is shared among different organs of government, such as the legislature, executive and judiciary. It is also termed as horizontal distribution of power because it allows different organs of government placed at the same level to exercise different powers. For example,  The distribution of power between Indian Parliament (legislature), the council of ministers headed by chief ministers (executive) and Courts of India.

(ii)  Power-sharing among various levels of governments: The power is shared among governments at different levels– a general government for the entire country and governments at the provincial or regional level. This is also called the federal division of power. Under this the Constitution clearly lays down the power of each level of government. For example, In India, power is shared among three levels of government which are Central government, State government and the local governments.

(iii) Power-sharing among different social groups: Power may also be shared among different social groups such as the religious and linguistic groups. For example, in India, reservations are made for the socially weaker sections of society in legislatures and bureaucracy.

(iv) Power-sharing among political parties, pressure groups and movements: Political Parties, Pressure Groups and Movements control or influence those who are in power. Different political parties contest elections for power which ensures that power does not remain in one hand. In the long run, power is shared among different political parties that represent different ideologies and social groups.

US and Soviet Union
The Cold War referred to the competition, the tensions and a series of confrontations between the US and Soviet Union. It never escalated into a hot war, i.e. a full-scale war between these two powers

Answer:
It is indeed very much true that slavery is a virtual death. Chandni, the goat, expressed her love for freedom by sacrificing her life. She fought a wolf boldly.
In the story I want something in a, cage, this love for freedom is expressed through a prisoner who spends all he had in order to buy freedom for a pair of birds.