Explore topic-wise InterviewSolutions in Current Affairs.

(c) Swami Dayanand Saraswati

(c) Dr. Ambedkar

(b) Swami Dayanand Saraswati

• Periyar E.V.R. was one of the greatest social reformers of Tamil Nadu.
• He advocated women education, widow remarriage and inter-caste marriages.
• He opposed child marriages.

• Sarada Sadan means Home of Learning. It was started by Pandita Ramabai in 1889. 
• It was started to educate Hindu widows in Bombay. 
• It was later shifted to Poona.

The principle is based on the property that the forces with which two charges attract or repel each other are not affected by the presence of a third (or more) additional charge(s). For an assembly of charges q₁, q₂, q₃, ..., the force on any charge, say q₁, is the vector sum of the force on q₁ due to q₂, the force on q₁ due to q₃, and so on. For each pair, the force is given by the Coulomb’s law for two charges. 

The electric field E at a point due to a charge configuration is the force on a small positive test charge q placed at the point divided by the magnitude of the charge. Electric field due to a point charge q has a magnitude |q|/4π ε₀r² ; it is radially outwards from q, if q is positive, and radially inwards if q is negative. Like Coulomb force, electric field also satisfies superposition  principle.

The SI unit of charge is Coulomb (C). 

One coulomb of charge is that charge which when placed at rest in vacuum at a distance of one metre from an equal and similar stationary charge repels with a force of 9 × 10⁹ N. One coulomb is evidently too big a unit to be used. In practice, in electrostatics, one uses smaller units like 1 mC or 1 µC. In CGS system, the unit of charge is stat coulomb or esu of charge.  

Surface density of charge is charge per unit area. Its SI unit is Cm^-2.

Correct option is  A) pupil

The crystalline lens provides the proper focal length required to focus objects at different distances on the retina.

Correct option is  B) iris

Pupil the human eye controls the amount of light entering the eye.

(a) Iris (b) Retina (c) Ciliary muscles

Pupil expands or contracts according to the intensity of light around the eye. 

(a) Cornea 

(b) Retina

The image formed in a human eye At retina

Eye lens changes its shape and thickness to focus light on to the retina

(i) Rational thinking, awareness, preservation of heritage.
(ii) They provided a link which can help scientists to study the process of evolution and know more about the world in which humans did not exist.
(iii) I would take the bones samples and send them for carbon dating to find which period they belong to.

At  t = 1 sec, s₁ = vt = 10x1 = 10cm
t = 2 sec, s₂ = vt = 10x2 = 20cm
t = 3 sec, s₃ = vt = 10x3 = 30cm

(c) The frequency = 25/π Hz.

(d) The amplitude = 0.001 mm.

EXPLANATION:  

Comparing with a wave equation  y = A sin ⍵(t -x/v) 

⍵ = 50 s⁻¹, ⍵/v = -2 →v = -50/2 =-25 m/s. Hence the option (a) is not true. 

2π/λ = ⍵/v = -2, →λ = -2π/2 = -π m. Hence the option (b) is not true. 

⍵ = 50 s⁻¹, →frequency = ⍵/2π = 50/(2*π) = 25/π Hz. Hence option (c) is true.Amplitude = 0.001 mm. Option (d) is correct. 

(b) The energy of any small part of a string remains constant in a standing wave.

EXPLANATION: 

In a traveling wave, energy is transmitted from one region of space to other but in a standing wave, the energy of one region is always confined in that region. Hence option (b) is true.

The two basic types of competitions are: 

i. Interspecific competition 

ii. Intraspecific competition

The intraspecific competition is more intense because the requirement of the individual of the species are similar.

Competition is defined as a process in which the fitness of one species is significantly lowered in the presence of another species.

Correct answer is (c) Verhulst-Pearl logistic growth

Two dogs fighting for same food. Two tomcats fighting for their territory.

Correct answer is (b) cardiac glycosides

I. Commensalism : Commensalism is the interaction between two species in which one species derives benefit and the other one is neither harmed nor benefited. 

II. Examples of commensalism:

1. Orchid grows as epiphyte on other big trees. The tree do not get any benefit but is neither harmed. But orchid gets support. 

2. Cattle egret is the insectivorous bird which forage close to cattle. When cattle move, the hidden insects in the grass are flushed out. These insects are then captured by egrets. Cattle do not get benefit but birds do. 

3. Sea anemone has stinging cells on the tentacles which offer protection to clown fish. Clown fish gets the protection from other predators, whereas, sea anemone does not derive any benefit from this association.

An orchid growing as an epiphyte on a branch of mango tree, is benefited due to support offered by mango tree but the mango tree does not get any benefit.

Correct answer is (d) Lichen seen on the tree

In CuO : (Cu of bivalent nature)

Eq. wt. of Cu. = 63.6/2 = 31.8

In Cu₂O : (Cu of monovalent nature)

Eq. wt. of Cu = 63.6/1 = 63.6  

No. of g-atoms of Carbon = mass of carbon / at. mass of carbon  = 120/12 = 10

1 g-atom of carbon has no. of atoms = 6.023 x 10²³

10 g-atoms of carbon has no. of atoms 10 x 6.023 x 10²³ or 10N.

N atoms of H has wt. = 1.008 g

1 atom of H has wt. = 1.008/6.023 x 10²³ = 1.67 x 10^-24 g

Correct answer is (b) sharing the table

(a) The interaction between two species in which one species gets benefits and the other is neither harmed nor benefited is called commensalism.

(b) The interaction between two species in which one parasitic species derives benefit from the other host species by harming it is called parasitism.

(c) Camouflage is the disguising colouration or behaviour to merge with the surrounding so that prey or predator can remain hidden.

On using the sine rule we know,

a/sin A = b/sin B = c/sin C = k

c/sin C = k

Therefore, c = k sin C

Similarly, a = k sin A

And b = k sin B

As we know,

Now let us consider the RHS

(b² – c²) sin A

By substituting the values of b and c in the above equation, we get

(b² – c²) sin A = [(k sin B)² – ( k sin C)²] sin A

= k² (sin² B – sin² C) sin A………. (i)

As we know,

Sin² B – sin² C = sin (B + C) sin (B – C),

By substituting the above values in equation (i), we get

 = k² (sin (B + C) sin (B – C)) sin A [since, π = A + B + C ⇒ B + C = π –A]

 = k² (sin (π –A) sin (B – C)) sin A

= k² (sin (A) sin (B – C)) sin A [since, sin (π – θ) = sin θ]

Then, rearranging the above equation we get

= (k sin (A))( sin (B – C)) (k sin A)

From sine rule, a = k sin A, therefore the above equation becomes,

= a² sin (B – C)

= RHS

Thus proved.

On using the sine rule we know,

a/sin A = b/sin B = c/sin C = k

c/sin C = k

Therefore, c = k sin C

Now similarly, a = k sin A

And b = k sin B

As we know,

Now let us consider the LHS

b sin B – c sin C

By substituting the values of b and c in the above equation, we get

k sin B sin B – k sin C sin C = k (sin² B – sin² C) ……….(i)

As we know,

Sin² B – sin² C = sin (B + C) sin (B – C),

By substituting the above values in equation (i), we get

k (sin² B – sin² C) = k (sin (B + C) sin (B – C)) [since, π = A + B + C ⇒ B + C = π –A]

Now the above equation becomes,

= k (sin (π –A) sin (B – C)) [since, sin (π – θ) = sin θ]

= k (sin (A) sin (B – C))

From sine rule, a = k sin A, therefore the above equation becomes,

= a sin (B – C)

= RHS

Thus proved.

For interaction of light with matter, it is necessary to consider the atomic nature of matter. Interaction of an atom with light depends on the frequency or equivalently on the photon energy.

An atom absorbs light if the photon’s energy equals one of the excitation energies of the atom. In the dense atomic neighbourhood of ordinary gases at pressures above 100 Pa, solids and liquids, the discrete atomic energy states widen into bands. Thus, bulk matter, depending on its nature, possesses absorption bands in specific regions within the electromagnetic frequency spectrum.

Radiant energy of other frequencies is elastically scattered so that the material is transparent at these frequencies.

[Note : Colourless, transparent materials have their absorption bands outside the visible region of the spectrum, which is why they are, in fact, colourless and transparent. Glasses have absorption bands in the ultraviolet region (~ 100 nm-200 nm), where they become opaque. At even longer wavelengths of radiowaves glass is again transparent. In comparison, a stained glass has absorption band in the visible region where it absorbs out a particular range of frequencies, transmitting the complementary colour. Semiconductors, such as ZnSe, CdTe, GaAs and Ge, which are opaque in the visible region of the spectrum are highly transparent in the infrared region (2 µm to 30 µm).]

1. Water, wood, iron, copper, moist air, benzene are athermanous substances. 

2. Quartz, sodium chloride, hydrogen, oxygen, dry air, carbon tetrachloride are diathermanous substances.

Radiation is the mode of heat transfer or in general, energy transfer by electromagnetic waves / quanta. Thermal radiation or heat radiation is the radiation produced by thermal agitation of the particles of a body, and its spectrum, i.e., frequency distribution or wavelength distribution, is continuous from the far infrared to the extreme ultraviolet region depending on the temperature of the body.

Properties :

1. Thermal radiations are electromagnetic waves/ quanta extending from the far infrared to the extreme ultraviolet region. In this spectrum, the infrared waves (wavelengths ranging from about 700 nm to about 1 mm) are sensed as heat.

2. They have the same speed in free space as that of light, nearly 3 × 10⁸ m/s, which makes radiation the most rapid mode of heat transfer.

3. They exhibit all the optical phenomena of light, viz., reflection, absorption, refraction, interference, diffraction and polarization.

4. Radiation incident on a body is, in general, partly reflected, partly, absorbed and partly transmitted.

5. Thermal radiation obeys the inverse square law of intensity, i.e., the intensity at a point is inversely proportional to the square of its distance from a point source of radiation.

(B) from 7700 Å to 4 × 10⁶ Å 

Correct Option is (B) 0.84

In case of opaque body transmitivity \(\gamma = 0\)

For any body relation \(\alpha + \beta + \gamma = 1\)

where,

\(\alpha =\) absorbtivity

\(\beta =\) Reflectivity

\(\gamma =\) transmitivity

\(\alpha + \beta +0 = 1\)

\(\alpha = 1 - \beta\)

\(\alpha = 1 - 0.16\)

\(\alpha = 0.84\)

Correct option is (B) 0.84

Data : r = 0.1, t = 0.2 

a + r + t = 1 

∴ a = 1 – r – f = 1 – 0.1 – 0.2 = 0.7

Radiant energy incident per minute on the body is 2000 J. Hence, in 2 minutes, the radiant energy (Q) incident on the body is 4000 J. Let Q_a , Q_r and Q_t be the quantities of radiant energy absorbed, reflected and transmitted in 2 minutes by the body, respectively.

(i) a = \(\frac{Q_a}{Q}\) 

\(\therefore\) Q_a = aQ = 0.7 x 4000 = 2800J

(ii) r = \(\frac{Q_r}{Q}\)

 \(\therefore\) Q_r = rQ = 0.1 x 4000 = 400J

(iii) t = \(\frac{Q_t}{Q}\)

 \(\therefore\) Q_t = tQ = 0.2 x 4000 = 800J

1. Lorentz force in earth’s magnetic field F =qvB

2. Electron

3. The earth’s magnetic field at poles is perpendicular to the earth surface. When an electron move, it is pushed to one side, parallel to earth’s surface.

 (c) remain same

EXPLANATION:  

The time period of a spring-mass system is given by T=2π√(m/k) Since this expression is not dependent on the acceleration due to the gravity, the time period T and hence the frequency (since ν=1/T) remains the same. The option (c) is correct.

Her worry becomes an obstacle in his development. She always makes him feel that he is an impaired boy and shall remain the same forever.

डेरेक (डेरी) की माँ एक सीधी-सादी महिला हैं। वह अपने बेटे के लिए हमेशा चिन्तित रहती हैं। उनकी चिन्ता उसके (डेरी के) विकास में बाधा बनती है। वह हमेशा उसे यह अहसास कराती रहती हैं कि वह एक अपंग लड़का है और हमेशा ऐसा ही रहेगा।

The poet fell into grief as he was passing through bad days. Misfortune and his poverty were pestering him.In his hour of need none came forward to help him. His friends and acquaintances deserted him leaving him alone to suffer in poverty.

चूँकि कवि के दिन खराब चल रहे थे इसलिए वह गम में डूब गया। दुर्भाग्य एवं गरीबी उसे द्रवित कर रहे थे। जब उसे जरूरत थी, तो कोई भी उसकी सहायता करने नहीं आया। उसके दोस्त तथा संबंधियों ने उसे गरीबी में नितांत अकेला छोड़ दिया।

The poet was passing through adverse circumstances. His poverty led him to fall into grief. Naturally, he needed someone to help him in that hour of need. He began searching for a friend who could stand with him in that hour of difficulties. Unfortunately, his search for a friend proved to be fruitless. No friend came forward to help him in tiding over his misfortune and poverty.

कवि प्रतिकूल परिस्थितियों से गुजर रहा था। गरीबी ने उसे गम में डुबा दिया। स्वाभाविक रूप से, जरूरत के समय उसे किसी की सहायता की आवश्यकता हुई। इन विपरीत परिस्थितियों में साथ देने के लिए उसने एक दोस्त की खोज प्रारंभ की, किंतु दुर्भाग्यवश, उसके दोस्त की खोज व्यर्थ साबित हुई। कोई भी दोस्त उसे दुर्भाग्य तथा गरीबी से उबारने के। लिए सामने नहीं आया।