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A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position.

In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armoured vehicles.

the correct answer of this question is C ,( 50 gm )

correct answer of this question is 50gm

50 gm is the correct answer

option b

Ans is 13m/s

Using Conservation of momentuminitial momentum = mv final momentum = M√5gl + mv/2

mv=M√5gl +mv/2

mv - mv/2 =M√5gl

mv/2 = M√5gl

v=(2M√5gl )÷m

V = 2(M/m)√5gl

option 3

thanks ma'am

Let's first write the name of elements according to their atomic number:

11 - Sodium

12 - Magnesium

14 - Silicon

15 - Phosphorus

14 - Chlorine

The largest atoms of these is Sodium.

This is because the outermost shell had only one election due to which the effective nuclear charge of the atom is less. Hence the electron is far from the nucleus due to which it is the largest atom.

Consider three incident rays of light encountering an interface between two media. In this example, the second medium is the slower medium and the rays are refracted towards the normal - note that angle A is greater than angle B in the diagram.

Since all rays are perpendicular to their respective wavefronts,m angle A + m angle 1 = 90m angle B + m angle 2 = 90

Since all normals are perpendicular to their respective interfaces,m angle C + m angle 1 = 90m angle D + m angle 2 = 90

Therefore, m angle C = m angle A and m angle D = m angle B so we can now examine the following new relationships:sin A = d1/Lsin B = d2/L

where L is the distance along the interface between points P1 and P2 as shown in the diagram below.

Solving each equation for L yields:L = d1/sin AL = d2/sin B

Therefore, d1/sin A = d2/sin B If d1 and d2 represent the distances traveled in the respective mediums during the same amount of time, then we can replace them with the expressionsd1 = v1td2 = v2t

But v1 and v2 represent the speed of the waves in each medium and can be replaced with the expressions n1 = c/v1 ---> v1 = c/n1 n2 = c/v2 ---> v2 = c/n2

where n1 and n2 are the respective indices of refraction and c is the speed of light. At this junction, we can now writed1/sin A = d2/sin Bv1t/sin A = v2t/sin B

(c/n1)(t/sin A) = (c/n2)(t/sin B) Canceling the common terms (c and t) yields(1/n1)(1/sin A) = (1/n2)(1/sin B)n1sin A = n2sinB

Or, as Snell's Law is more commonly expressed: n1sin theta1 = n2sin theta2

Notice that Snell's Law shows that the index of refraction and the sine of the angle of refraction are inversely proportional - that is, as the refractive index gets larger [n2 > n1] the sine of the refracted angle gets smaller [sinθ2 < sinθ1], since the product of the two terms must remain a constant.

derivative of e^(-x) is - e^(-x) using chain rule as differentiating e^(-x) is remains same and then differentiating -x is -1

Floor of soapy water will reduce friction that will make difficult for a person to make contact with floor and chance of falling is higher.

Genetic Screening or Testing:Genetic tests are done by analyzing small samples of blood or body tissues. They determine whether you, your partner, or your baby carry genes for certain inheriteddisorders. Genetic testing has developed enough so that doctors can often pinpointmissingordefectivegenes.

downward.. below the plane of of the paper..

E=-13.6Z^2/n^2eVn=1E=-13.6*3^2/1^2=-122.4eV

In October of 1651, the English Parliament passed its Navigation Acts of 1651. These acts were designed to tighten the government's control over trade between England, its colonies, and the rest of the world. In passing the Navigation Acts, the English government was also trying to work out a practical application of one of its favourite economic theories, namely, mercantilism.

Resistence of wire A =10 ohm.

therefore resistence of thinner wire=3*10=30 ohm. (R=pl/A)

total R = 10+30=40 ohm..(since they are in series)

The pressure at a point inside a liquid depends on the depth of point from the free surface, therefore, the pressure is very high at the bottom of the dam. To tolerate this pressure, the walls of dam are made thick at the bottom. As we move upwards, the pressure goes on decreasing: so the thickness of wall is made smaller and smaller. That is why the walls of dam are made thick at the bottom and thin at the top.

As per my point of view electromagnets are better to use rather than natural magnets. Natural magnets though they don't require any kind of electricity or some other form of energy should not be used due to some reasons. (1) sometimes we require a strong magnetic field to be generated, using electromagnets this would be easy, by just increasing the amount of electricity. But for natural magnets this would be one constraint. ( 2) natural magnets once banged by some accident or some other reason lost their magnetic properties to some extent or completely. This is also possible when they are exposed to high heat for long time . Electromagnets are not affected by this. (3) moreover it is not easy to handle natural magnets and can't be used easily by cranes for lifting purpose as it would create mess for dropping the lifted things and will slow down the work. By using electromagnets no such problems would be created.

1)The reason for the covering of wire with rubber is that as rubber is insulator it doesn't conduct electricity so if it would not be covered with insulator then anyone can get shock and he would suffer current which can led to his death also.

2)To study magnetic field , an electromagnet can be made using iron nal, wire and battery.For making electromagnet, iron nailed is first coiled with wire and then the wire is connected to a battery. When any magnetic material is brought near the bar magnet, it will got attracted towards the magnet . While any non-magnetic material will not get attracted by it. Thus the effect of magnetic field can be studied that a magnet attracts magnetic material or objects. And bar magnet is a parmanent magnet that will always attract magnetic material, unlike iron nail that required a battery connection to work as a magnet . So magnetic field can be studied by comparing magnetism created using two types of magnet that is parmanent magnet that is bar magnet . And temporary magnet that is electromagnet .

4.Thosematerialswhich are not attracted by amagnetare called non-magnetic materials. All thesubstancesother than iron, nickel,andCobalt are non-magnetic substancesforexampleplastic, rubber, water, etc are nonmagneticmaterials. Non-magnetic substancescannot be magnetized.

4) the materials which are attracted by a magnet is called a magnetic materialexample:- when we bring an iron bar close to a magnet, we can see that the magnet is attracting the iron bar5) an electromagnet can be created by a flow of current in the object whereas a permanent magnet is magnetizedthe property of an electromagnet depends on the amount of current flows in the object, but permanent magnets properties are depending upon the magnetizing material

A projectile is an object that is given an initial velocity, and is acted on by gravity. The amount oftimeit spends in the air is called thetime of flight. ... The unit for thetime of flightis seconds (s).

Time of flight is a property of an object, particle or acoustic, electromagnetic or other wave. It is the time that such an object needs to travel a distance through a medium. The measurement of this time can be used for a time standard, as a way to measure velocity or path length through a given medium, or as a way to learn about the particle or medium. The traveling object may be detected directly or indirectly.

Applying nodal so10/2-3= 5-3= 2A

10/2= 5nowix= 5/2= 2.52.6 Aapprox

Ix= 10/2= 5now 5-2 as its being divided by nodeand 3 is incoming currentsoincoming current = outgoing current= 5-3= 2A

answer is black formed by copperwire

black colour is formed

Let α be the linear expansion coefficient for a material. Then:

(E1) ΔL / L0 = α * ΔT

Since we are given a linear dimension (the diameter), we can use it, together with (P1) and (E1), to calculate the temperature T. First,

(E2) ΔT = T - T0 = T - 30and(E3) ΔL = L - L0 = 1.00000 - 0.99970 = 0.00030cm

Substituting into (E1):

(E4) ΔL / L0 = α * (T - 30)

= α * T - α * 30

Solving for T:

(E5) T = (ΔL / L0 + α * 30) / α

= (ΔL / L0 ) / α + 30

and substituting from (E3):

= (0.00030 / 0.99970 ) / α + 30

= 0.00030 / α + 30

Now all we need to know is what material the plate is made of, plus an experimentally determined value for α at 30C for that material.

If the material is steel and we assume that

(E6) α30 ≈ α20,

then

(E7) T = 0.00030 / α + 30

= 0.00030 / 13e-6 + 30

= 53.C

-v/u is the magnification formula for a mirror.Since, it is found to be +1/5, hence the image is magnified.

thanks

I will ask another question wait

The force acting on an object perpendicular to the surface area is called thrust.

The thrust on unit area is called pressure.

Pressureis defined as the force per unit area. If a force F is applied on a surface of area A, then the pressure P is defined as:

P =F/A

The force acting on an object perpendicular to the surface is called thrust

Thrust = 150NArea = 10 m^2

PRESSURE = thrust/ area= 150 N/10 m^2 = 15 N/m^2= 15 pascal

Thrust is the force acting nornally on a surface. Its SI unit is newton (N). Pressure is force per unit area. Its SI unit is pascal (P) or newton per square metre (N/m2).

The force acting per unit area is known as pressure.

Difference between thrust and pressure:-Thrustis the total force acting perpendicular to the surface. The unit ofthrustis Newton. The force acting (thrust) per unit area is calledpressure.Thrustis the total force acting perpendicular to the surface. The unit ofthrustis Newton. The force acting (thrust) per unit area is calledpressure. Its unit is Newton per sq. metre or Pascal.

Pressure(symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.

Inthrustthere is a internal reaction such as in Jet engines or rocket engines which causes force. ... AlsoThrustis the total force acting perpendicular to the surface. The unit ofthrustis Newton. The force acting over unit area is called pressure.

areas of the flat keel plate=(10 x 2)=20m² pressure= (depth x density)8.2t/m²thrust=(pressure x area)=164t

164 t is the best answer

164 is the right answer

Uranium thorium and palladium are radioactive elements

164 is the right answer

164 is the right answer

165 is the correct answer

d is the right answer

Weight is not a force. The force you experience through weight is gravity.

(d) is correct option

impulse, thrust, tension, weight all are force.

weight is not a force.

Impulse is defined as the product of the force and the time during which the force acts. Rearrangement of Newton's second law tells us that impulse equals to the change in momentum.

(a) is correct option

impulse is not force, options no (a)

when we want to see any types of thing so we use our eyes

Eyes are organs of the visual system. They provide organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons

By far the most important organs of sense are our eyes. We perceive up to 80 per cent of all impressions by means of our sight. And if other senses such as taste or smell stop working, it's the eyes that best protect us from danger.

with eyes only we see and we can only do our work with eyes in these ways eyes are used to us

If the door of the refrigerator is kept open in a room, it warms up the room.

Explanation:-

Running the refrigerator makes the room warmer and if you leave the door open, the room warms up even faster. The first rush of cold air may cool things down a little, but in the long run, the room will get warmer.

To see why, we need to think of heat as energy and cold as a lack of energ.But the refrigerator can’t actually produce cold. All the refrigerator does is move heat, or energy, from one place to another. As the food inside the refrigerator loses its heat–or, in other words, gets colder–thatheat ends up in the room.

1 st one is correct answer

pls solve this

thanks a lot for answering me

They bump into the walls of any container that holds them. They bump into objects in the fluid. As the particles of a fluid bump into an object in the fluid, they apply forces to the object. The forces, acting over the object's surface, exert pressure on the object.

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