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Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can be seen only when exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after

fmin a = 0.4*2*50 = 40

fmin b = 0.4*2*100 = 80

fmina/fmimb = 40/80 = 1/2

In circuit 1,R1/9 = 4/6thus, R1= 6 ohms

In circuit 2,6/R2= 12/8Thus, R2 = 4 ohms

Therefore,R1/R2= 3/2

i) myopia is correct option, because they spread the light out before it reaches the convex lens in the eye, therefore letting the imagefocusdirectly on the retina. H

Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.

the unwanted items which are present in pure substance.

option c is the answer

wheatstone bridge So current through 4 = 0

so neglect 4

2 and 5 are in series So 7

7 and 7 are in parallel

49/14 = 3.5

Lenses are used to focus light. Because focusing light is so important, you can find lenses in many places.

Perhaps the most common lens that we see are the ones in peoples glasses. There is a small lens in each of our eyes. When that lens isn't shaped quite right, light doesn't focus clearly and it's hard to see things. Glasses put another lens in front of the eye to help focus the light better for us. Then we can see clearly.

Another place to find a lens in in a CD player. A CD player works by shining a laser (which is a type of light) onto a disc. The lens in the CD player helps focus the laser onto the disc. Without that lens, the CD player can't read anything.

Lenses are also used in telescopes. When we look up at the sky, we see lots of stars. But we can use a telescope to look at a specific star. The lenses in the telescope focus the light from a single star so that the star we're looking at appears larger so it is easier to see.

Please resend it at for short 4 points because it is only for 2marks

.Modern periodic law states that “The physical and chemical properties are the periodic functions of their electronic configuration”.

.The electronic configuration of the atoms of element represent the position of the atom in periodic table.

.The electronic configuration of the atoms helps to predict the physical and chemical properties of the elements.

.It gives the information about the reactivity, metallic nature and all physical and chemical properties of the element.

.So, by only the electronic configuration of the element, we predict all the prop-erties of that element. Hence I appreciate the role of electronic configuration of the atoms of elements in periodic classification.

The conversion of vegetable oil to vegetable ghee is called hydrogenationreaction.

Aforceis a push or pull acting upon an object as a result of its interaction with another object. Basically, there are two types of forces, contact forces, andnon-contact forces. Gravitational force, electric force, magnetic force, nuclear force, frictional force are some examples of force.

a=9248/69886farzinfnffs dxgbdj

Resultant = Theresultantis thevectorsum oftwoor morevectors. It is the result of addingtwoor morevectorstogether. ... Iftwoor more velocityvectorsare added, then the result is aresultantvelocity. Iftwoor more forcevectorsare added, then the result is aresultantforce.

R= 7i+7j+7kmagnitude = √49+49+49√147 unut

approximately 23

a = 12 ; b = 13 ; R = ? ; Q = 45°

=> R = √ ( a^2 + b^2 + 2 a . b . cos Q )

=> R = √ ( 12^2 + 13^2 + 2 . 12 . 13. cos 45 ° )

=> R = = √[144 + 169 + 312 (1/√2)]

=> R = √(313 + 220.65)

=> R = √(533.65)

=> R = 23.10

yes.. for example. . a vector along y axis 2j has 0 component along x .. but has 2 as its magnitude.

Water’s density increases as you continue to cool it; but opposed to other liquids, which have their highest density when they freeze, water achieves maximum density when its temperature reaches 4 degrees Celsius (39.2 Degrees Fahrenheit).If you continue to cool water past 4 degrees Celsius, its density starts to plummet At zerodegrees, i.e., the temperature at which water turns into ice, the density of wateris actually quite low.

It turns out that ice has a lower density than water, and any object that has a lower density than the liquid form on which it’s kept (in this case, water) will be able to float!

Density of water = 1 g/cc

fraction of volume above surface

=density of ice/ density of water

= 0.9/1

=9/10

value in percentage will be..........

All of us observed that ice floats on water because ice cube is made up of water (h2o). water contain 2hydrogen and 1oxygen molecules presence of oxygen molecules ice floats on water

hlo

thank u fo accepted my answer as best

This can be proved by dot product of A and B

A•B = |A||B|cos∅ => cos∅ = A•B/(|A||B|)

so, A•B = (AxBx +AyBy+AzBz)

and |A| = √Ax²+Bx²+Cx² ; |B| = √Bx²+By²+Bz²

=> cos∅ = (AxBx+AyBy+AzBz)/√Ax²+Bx²+Cx².√Bx²+By²+Bz²

Two vectors are a and b.

(a+b) × (a-b) = a×a+b×a-a×b-b×b. (Distributive Law)

(a+b) × (a-b) = 0+b×a + b×a-0.

(a×b) = -(b×a).

(a+b) x (a-b) = 2*b×a.

b×a = |b|*|a|*sin(∆).

Where, ∆ is angle between b and a.

Hence, (a+b) × (a-b) = 2*|b|*|a|*sin(∆).

the answer could be option c

Total weight of body will be equal to weight of water surrounded by body(bouyant force),which gives us density of body. Such as

If d and v are density and volume of body and w and O is density of water and oil.

So Wight of body = weight of water displaced by body.

d*v*g=w*0.6*v*g

So. d=600 kg/m3.

Now in the case of oil. same concept is applied.

Wight of body = Wight of oil displaced by body

d*v*g=O*0.4*v*g

So. O = 1500 kg/m3.

Now we know that. Relative density =K/2.

Relative density = oil density/water density

So . K/2 = 1500/1000

So K=3.

" Photosynthesis "

It is the process by which green plant and some other organism use sunlight to synthesize nutrients from carbon dioxide and water.

The main product form here is glucose and by products are oxygen and water.

Here it takes place in chlorophyll and in the presence of sunlight.

There are two stages of photosynthesis :

1. Light reactions :

It occurs in the grana where photon are absorbed so as to excite electrons of chlorophyll to a higher energy level. These activated elctrons are harnessed to form ATP from the ADP and reduce NADP to NADPH. Wayer ia also spotted here and oxygen is released.

2. Dark reactions :

Calvin cycle occurring in chlorophyll here carbon combine with 5-carbon sugar called ribulose biphospahte. This unstable compound breaks down into 3-carbon compound. This then forms glucose.

Sin²15° + sin²645° we know, sin(n × 360° - Ф) = -sinФ , use this here [ n is integers ]Sin645° = sin(2 × 360 - 75°) = - sin75° And we know, sin(90 - Ф) = cosФ So, - sin75° = -sin(90-15°) = -cos15°

Hence, sin645° = -cos15° Now, sin²15° + {-cos15°}² = Sin²15 + cos²15° = 1 [ ∵ sin²x + cos²x = 1 ]

Hence, answer should be 1

A plane curve generated by a point moving so that its distance from a fixed point is equal to its distance from a fixed line

Magnitude of the resultant of two vectors of equal magnitude = 2p cos(x/2)

Where x is the angle b/w them and p= magnitude.

Substituting x= 120,

We get mag. = P.

Therefore, Magnitude of the resultant is equal to the magnitude of the vectors.

thank you

Ans 0...............

can you please explain why ?

The three forces will be along three directions separated by 120 deg. from each other drawn at a point P. Let them be PA of 1 N. PB = 2 N and then PC = 3 N..

Let us draw PA horizontally along positive x axis.PB is at 30 deg. anticlockwise from + y axis.PC will be at 30 deg. clockwise from - y axis... Resolving components along x axis and adding: = 1 N + 2 N * Cos 120 + 3 N * Cos 240 = 1 - 2 * 1/2 - 3 /2= - 3/2 Newtons Resolving components along y axis and adding = 0 N + 2 N *√3 /2 - 3 N *√3/2 = -√3/2 Newtons

So resultant is R = -1.5 i -√3 /2 j where i and j are unit vectors. magnitude = √[ 1.5² + 3/4 ] =√3 Newtons.

The three vectors form closed triangle, so the resultant is 0.

yes it correct answer

I = 0.2.5 ma oxo ve if DJ CR

Option A

1st option is correct answer

(1)3000of 10to power 5upon 530

(1)3000 of 10 to power 5 upon 530

13x is your answer

thank you