Explore topic-wise InterviewSolutions in Current Affairs.

(d) Rain baseras

House of the sea coast are made of Wood.

By distillation under reduced pressure.

The Earth is called the ‘blue planet’ because when it is seen or photographed from space,it appears blue due to the reflection of light from the water on its surface.It is so called also because three fourth or more than 71 per cent of its surface is covered with water.

The different layers of atmosphere are: troposphere, stratosphere, mesosphere,thermosphere and exosphere.

The four major domains of the Earth are: lithosphere, hydrosphere, atmosphere and biosphere.The lithosphere is land,hydrosphere is water and atmosphere is the air domain of the Earth.Biospere is where all the other three spheres meet ,and it supports all forms of life.

It is the ratio of the distance travelled by the substance from base line to the distance travelled by the solvent from the base line.

The two continents that lie entirely in the Southern Hemisphere are: Australia and Antarctica.

The seven major continents of the Earth are: Asia, Europe, Africa, North America, South America, Australia and Antarctica.They cover about 29 percent of the Earth's surface.

The Northern Hemisphere is called the Land Hemisphere because the greater part of Earth’s land mass lies in the Northern Hemisphere.

(a) Sodium oxide (Na₂O), potassium oxide (K₂O) are metal oxides which are water soluble.

(b) Copper (II) oxide (Cu₂O), Beryllium oxide (BeO) are metal oxides which are water insoluble.

The biosphere is the narrow zone of contact between land, water and air. It is in this zone that life, that is unique to Earth, exists as a result of interaction between land ,water and air. All the living organisms are linked to each other and to the biosphere for survival.

Correct option is (C) 0.6 π rad

Correct option is (B) 0.16 s

We can get highly enlarged image at infinity when we place paper at focal point.

The distance between focus and vertex.

The surface used for reflection is called reflecting surface.

Einstein’s photoelectric equation :

hv = Φ + \(\cfrac12\)mv²_max....(1)

where h ≡ Planck’s constant, v ≡ frequency of the electromagnetic radiation, hv ≡ energy of the photon incident on a metal surface, Φ ≡ photo-electric work function, i.e., the minimum energy of light quantum required to liberate an electron from the metal surface, v and –  \(\cfrac12\)mv²_max ≡ the maximum speed and maximum kinetic energy of the photoelectrons at the time of emission. Φ = hv₀, where v₀ is the threshold frequency for the metal.

Explanation of the characteristics of photoelectric effect:

(1) From the above equation we find that for photoejection, hv ≥ Φ. That is, hv_min = hv₀ must be equal to Φ. Hence, photoelectric effect is observed only if hv ≥ hv₀ , i.e., v ≥ v .

This shows the existence of a threshold frequency v₀ for which photoelectrons are just liberated from a metal surface (with zero kinetic energy). Since different metals differ in electronic configuration, the work function hv and, therefore, frequency v are different and characteristic of different metals.

(2) In this particle model of light,’ intensity of incident radiation’ stands for the number of photons incident on a metal per unit surface area per unit time. As the number of photons incident on a metal per unit surface area per unit time increases, there is a greater likelihood of a photon being absorbed by any electron. Therefore, the time rate of photoejection and hence photoelectric current increases linearly with the intensity of the incident radiation (v ≥ v₀).

(3) From Eq. (1), \(\cfrac12\)mv²_max , = hv – Φ= h(v – v ) This shows that the maximum kinetic energy in-creases linearly with the frequency v of the incident photon (v ≥ v₀) and does not depend on the time rate at which photons are incident on a metal surface.

(4) As the incident energy is concentrated in the form of a photon, and not spread over a wavefront, it is expected that an electron is emitted from the metal surface as soon as a photon (v ≥ v₀) is absorbed. This is in agreement with the experimental observation.

[Note : The frequency v that appears in the formula E = hv is the frequency of the oscillating electric field / magnetic field in the electromagnetic wave. ]

Max Planck put forward the quantum theory in 1900 to explain blackbody spectrum. In the theory, he proposed that the electromagnetic radiation emitted by the body consists of discrete concentrated bundles of energy, each equal to hv, where h is a universal constant (now called Planck’s constant) and v is the frequency of the radiation.

Einstein put forth (1905) that these energy quanta, called light quanta/later called photons, interact with matter much like a particle. When a photon collides with an electron in an atom, the electron absorbs whole of the photon energy hv in a single collision or nothing. The electron uses this energy (1) to liberate itself from the atom, (2) to overcome the potential energy barrier at the surface thus liberating itself from the metal, and (3) retains the remaining part as its kinetic energy. Different electrons need different energies in the first two processes. There are some electrons which use minimum energy in the two processes, and hence come out of the metal with maximum kinetic energy. The minimum energy required, in the form of electromagnetic radiation, to free an electron from a metal is called the photoelectric work function Φ of that metal.

Thus, for the most energetic photoelectrons at the time of emission,

maximum kinetic energy of the electron = photon energy – photoelectric work function

∴ \(\cfrac12\) mv²_max = hv – Φ 

∴ hv = Φ + \(\cfrac12\)mv²_max

The above equation is called Einstein’s photoelectric equation.

Light interacts with matter as concentrated bundles of energy rather than energy spread over a Huygens type wavefront. Even under weak irradiation, an electron absorbs a photon’s energy in a single collision. But the rate of incident photons in dim light being less, the chances of such absorption diminish and consequently the photoelectric current diminishes. However, a photoelectron is emitted as soon as a photon is absorbed.

[Note : Albert Einstein (1879-1955), German Swiss- US theoretical physicist, gave his photoelectric equation in 1905. In the period 1912-1916, Robert Andrews Millikan (1868 -1953), US physicist, was the first to obtain the precise experimental data from which the straight-line graphs, like the one shown in Fig. 14.6, were plotted for various metals. Einstein’s theoretically predicted equationclearly having the right form for a straight-line graph-was thus verified.]

D. atmospheric pressure 

Atmospheric pressure exerted by air .

The energy of radio photon is less than the work function of any metal so even sufficiently powerful AM radio signal cannot produce photoelectric effect. 

Maximum kinetic energy of photoelectrons depends on the nature of the emitter and the frequency of incident radiation. 

2 units.

Explanation:

We know that, y coordinate represents the distance from the x axis. So the answer is 2 units.

two (a pair)

Explanation:

To represent the point on the graph we need a pair of coordinate, where one represents the x coordinate and the other represents the y coordinate.

Graph

Explanation:

The graph defines the relationship between the two variables where one is the dependent variable and the other one is the independent variable.

True

Explanation:

For plotting a point, we need two coordinates such as x coordinate and y coordinate.

Plotting

Explanation:

The process of fixing the point using the coordinates is known as the plotting of points on a graph.

X-axis, Y-axis

To draw a graph we need pairs of points known as coordinates and to plot a point we require two mutually perpendicular axes, also known as the X-axis (horizontal line) and the Y-axis (vertical line).

x coordinate

Explanation:

The distance of any point from the x axis is called y coordinate and the distance of any point from the y axis is called the x coordinate.

x- coordinate.

Explanation:

The first number in the ordered pair represents the x coordinate and the second number represents the y- coordinate.

4 units.

Explanation:

In the ordered pair, the first number always represents the x coordinate and the second number represents the y coordinate. Hence, the y coordinate is 4 units.

zero

Since, the x-coordinate represents the distance of the point from Y-axis is zero, therefore the points lying on the Y-axis have x-coordinate as zero.

False

The ordinate of a point is nothing but coordinate of the point and the y-coordinate denotes the distance of a point from X-axis.

Observing the given graph carefully, we have

(a) At 8 AM, the temperature is 7°C.

(b) At 6 AM, the temperature is 3°C.

(c) The temperature fall in the hour 5 AM to 6 AM.

(d) The change in temperature is 3°C between 7 AM and 10 AM.

(e) Between 8 AM to 9 AM, there was a constant temperature.

Observing the graph carefully, we conclude that

(a) Vendor A has sold more ice-creams on Friday.

(b) On Sunday , the sales was the same for both the vendors.

(c) On Sunday, the sale of vendor A increased the most as compared to Saturday.

(d) The difference in sales was the maximum on Thursday.

(e) On Tuesday and Wednesday, the sales was the same for vendor B.

On observing the graph carefully, we note that

(a) The brands E and F cost more than brand D.

(b) The bag of sugar of brand D is the heaviest.

(c) The weights of bag of brand S and F; brand E and C weighs same.

(d) Brands C, D, E are heavier than brand B.

(e) Bag of brand A is the lightest.

(f) Bags of brand A and C are of the same price.

Observing the graph carefully, we conclude that

(a) In April, the actual sales was same as the expected sales.

(b) In March, the difference in actual and expected sales was the maximum.

(c) In April, the difference in actual and expected sales was the least.

(d) The total sales of cars in the months January, February and March was (75 + 100+75) i.e. 250.

(e) The average sales of cars in the last three months is 125 i.e.125 + 100+ 150/3 = 125.

(f) The number of sales of car in the first three months = 250 and the number of sales of car in the last three months = 375

The required ratio is 250 : 375 i.e. 2:3,

(a) (i) In 2002, the sales were Rs 4 crores.

(ii) In 2006, the sales were Rs 8 crores.

(b) (i) In 2003, the sales were Rs 7 crores.

(ii) In 2005, the sales were Rs 10 crores.

(c) (i) In 2002, the sales were Rs 4 crores and in 2006, the sales were Rs 8 crores. Difference between the sales in 2002 and 2006 = Rs (8 − 4) crores = Rs 4 crores

(d) Difference between the sales of the year 2006 and 2005 = Rs (10 − 8) crores = Rs 2 crores

Difference between the sales of the year 2005 and 2004 = Rs (10 − 6) crores = Rs 4 crores

Difference between the sales of the year 2004 and 2003 = Rs (7 − 6) crore = Rs 1 crore

Difference between the sales of the year 2003 and 2002 = Rs (7 − 4) crores = Rs 3 crores

Hence, the difference was the maximum in the year 2005 as compared to its previous year 2004.

False

We know that the x-coordinate of a point represents the distance of the point from Y-axis. Here x-coordinate is 3, so the distance of the point (3,5) from the Y-axis is 3.

Points whose x and y coordinates (0, 0), (1, 1), (2, 2) etc are equal, lie on a line passing through the origin.

For above statement we can conclude that our statement satisfies the equation x = y.

For x = 0 and y = 0, this equation gets satisfied.

∴ Given statement is true.

False

The distance of any point from the X-axis is called the y-coordinate.

False

Explanation:

The point (3, 5) and (5, 3) does not represent the same point.

From point (3, 5), the x coordinate is 3 and the y coordinate is 5

From point (5, 3), the x coordinate is 5 and the y coordinate is 3

When these points are plotted in graph, you will get the different graph.