Description : Pick up the correct statement from the following: (A) The refractive index of a medium varies according to the wavelength of the radiation, (B) The variation of the refractive index with wave length, ... of white light by passing through a prism is caused due to dispersion (D) All of these
Last Answer : Answer: Option D
Description : The sky appears blue because of – (1) Atmospheric water vapour (2) Scattering of light (3) Reflection on sea water (4) Emission of blue wavelength by the sun
Last Answer : (2) Scattering of light Explanation: The sky is blue because the molecules in the air scatter light in the higher wavelengths (that is, the blue light), while lower wavelength light (that is ... reflected down from the scattering is blue, therefore a blue sky. This is called Rayleigh scattering.
Description : The blueness of the sky is mainly due to -------? A. The scattering of sunlight by air molecules (Answer) B. The presence of water vapor C. Absorption of blue light by the air D. Emission of blue light by the atmosphere
Last Answer : A. The scattering of sunlight by air molecules (Answer)
Description : When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy state, they emit light, which we can observe in - (1) Raman spectra (2) Absorption spectra (3) Emission spectra (4) Fluorescence
Last Answer : (3) Emission spectra Explanation: When a metal atom is strongly heated, its electrons absorb the heat energy and jump to a higher energy level. When the electron returns to its original position it ... to the energy the electron has released at each stage °fits fall back to its original state.
Description : The mercury and sodium street lamps light up because of – (1) Atomic emission (2) Atomic absorption (3) Electron emission (4) Electron absorption
Last Answer : (1) Atomic emission Explanation: The light in sodium vapour lamp and mercury vapour lamp is, because of electron emission. In case of Sodium Lamps, filaments of the lamp sputter ... energy levels and the electrons thus excited relax by emitting the characteristic monochromatic bright yellow light.
Description : Stars appear twinkling because of ______ of light. (1) Reflection (2) Scattering (3) Emission (4) Absorption
Last Answer : (2) Scattering Explanation: The stars' light must travel through the Earth's multi-layered atmosphere, and as it does so it is refracted (bent) multiple times and in random directions. The phenomenon of ... star wink as though it is in motion. It is this action that our eyes translate as twinkling.
Description : When a metal is heated in a flame, the electrons absorb energy and jump to higher energy state. On coming back to the lower energy siate, they emit light, which we can observe in (1) Raman spectra (2) Absorption spectra (3) Emission spectra (4) Fluorescence
Last Answer : Emission spectra
Description : The mercury and sodium street lamps light up because of : (1) Atomic emission (2) Atomic absorption (3) Electron emission (4) Electron absorption
Last Answer : Atomic emission
Description : Stars appear twinkling because of ......... of light. (1) Reflection (2) Scattering (3) Emission (4) Absorption
Last Answer : Scattering
Description : If a wave travels at a constent speed the greater its wavelength the lower its?
Last Answer : Need answer
Description : The danger signals are red while the eye is more sensitive to yellow because – (1) absorption in red is less than yellow and hence red is visible from a distance (2) scattering in yellow light is less than red (3) the wavelength of red light is more than yellow light (4) none of the above reasons
Last Answer : (3) the wavelength of red light is more than yellow light
Description : A 'body' which allows the short wavelength incoming solar radiation to enter in, but does not allow long wave length outgoing infra red radiation to escape out is called the (A) Global warming (B) Green house (C) Atmospheric effect (D) Ionosphere
Last Answer : (B) Green house
Description : The beautiful color patterns exhibited by a peacock in its tail feathers are due to ? A. Selective absorption of light (Answer) B. Selective re ection of light C. Sinterference of light D. Natural colour pattern of feathers
Last Answer : A. Selective absorption of light (Answer)
Description : An instrument has two strings. Both have the same length and are uniform. One of the strings is under twice as much tension as the other and also twice the mass of the other. Then which of ... d) Both strings vibrate with the same frequency and have the same wave-length and the same wave velocity.
Last Answer : Ans:(d)
Description : Higher concentration of CO2 in atmosphere (A) Allows visible solar radiation (ultraviolet) of short wave-length to pass through (B) Reflects and absorbs the longer wavelength (infra-red) radiations (C) Prevents solar heat being ... in 'heat trap' i.e., global warming (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : A string of length L is fixed between two points. If a standing wave of 5 nodes is produced, what is the relationship between the string's length, L, and its wavelength?
Last Answer : ANSWER: WAVELENGTH = 1/2 L
Description : The rate of emission of radiation by a body does not depend upon the (A) Wavelength of radiation (B) Surface temperature of the body (C) Nature of the surface (D) Shape and porosity of the body
Last Answer : (D) Shape and porosity of the body
Description : Pick out the wrong statement. (A) Biological oxygen demand (B.O.D.) value of a sewerage sample is always lower than its chemical oxygen demand (C.O.D.) value (B) Environmental pollution by ... in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere
Last Answer : (D) The characteristic of a green house body is that it allows the long wavelength incoming solar radiation to come in but does not allow the short wavelength infra red radiation to escape out of the earth's atmosphere
Description : The process of moving from one energy level to another is called ____________. ∙ A. Spontaneous emission ∙ B. Excited emission ∙ C. Absorption ∙ D. Spontaneous decay
Last Answer : C. Absorption
Description : The process of decaying from one energy level to another energy level is called __________. ∙ A. Spontaneous emission ∙ B. Excited emission ∙ C. Absorption ∙ D. Any of these
Last Answer : A. Spontaneous emission
Description : According to Bohr's theory, an electron in one Bohr stationary orbit can go to a higher stationary orbit (a) By emission of electromagnetic radiation (b) Without any absorption ... absorption of any electromagnetic radiation (d) With absorption of electromagnetic radiation of a particular frequency
Description : (a) `[Ti(H_(2)O)_(6)]^(3+)` absorbs light of wavelength 5000Å. Name one ligand which would form a titanium (III) complex absorbing light to lower wave
Last Answer : (a) `[Ti(H_(2)O)_(6)]^(3+)` absorbs light of wavelength 5000Å. Name one ligand which would form a titanium (III) ... ^(3+)" " (iv) [Pd(en)_(2)]^(2+)`
Description : What is the frequency of a light wave with a wavelength of 6.80 x 10-7 m?
Last Answer : The frequency is 4,4087.10e5 GHz.
Description : When a light wave is reflected from a mirror, there is a change in its – (1) frequency (2) amplitude (3) wavelength (4) velocity
Last Answer : (2) amplitude Explanation: When a light wave is reflected from an object, it changes not only its amplitude but also its phase according to the properties of the object at a particular point. The velocity and momentum are just reversed in another direction.
Description : When a light wave suffers reflection at the interface between air and glass medium, the change of wavelength of the reflected wave in air is equal to (a) 0 (b) λ/2 (c) λ (d) 2λ
Last Answer : (b) λ/2
Description : When light is traveling through a vacuum, what is the product of the light's wavelength and frequency equal to? w) speed of light x) Plank's constant y) momentum z) wave number
Last Answer : ANSWER: W -- SPEED OF LIGHT
Description : When a light wave is reflected from a mirror, there is a change in its (1) frequency (2) amplitude (3) wavelength (4) velocity
Last Answer : amplitude
Description : Pick out the wrong statement. (A) Denier is defined as weight in gm of 9000 metres length of a fibre, while tex is defined as weight in gm of 1000 metres length of fibre (B) ... fibres are all prepared by wet spinning (D) Nylon fibres have greater water absorption capacity than polyester fibres
Last Answer : (C) Dacron fibres, acrylic fibres, viscose rayon fibres & cellulose acetate fibres are all prepared by wet spinning
Description : Scattering losses are caused by the interaction of light with density fluctuations within a fiber. What are the two scattering mechanisms called when the size of the density fluctuations is (a) greater than and (b) less than one-tenth of the operating wavelength?
Last Answer : . (a) Mie scattering; (b) Rayleigh scattering.
Description : .A beam of light is incident on a large block of glass. The index of refraction of the glass is greater than one. Is the wavelength of the light in the glass? A. Longer than B. Shorter than C. The same as the wavelength of the light in the air? D. None of above
Last Answer : B. Shorter than
Description : To find prominent diffraction , the size of diffraction object should be A. greater than wavelength of light used B. comparable to order of wavelength of light C. less than wavelength of light used D. none of these.
Last Answer : B. comparable to order of wavelength of light
Description : A beam of light is incident on a large block of glass. The index of refraction of the glass is greater than one. Is the wavelength of the light in the glass: w) longer than x) shorter than y) the same as the wavelength of the light in the air?
Last Answer : ANSWER: X -- SHORTER THAN
Description : Results in reduction in the power of light wave as it travels down the cable. ∙ A. power loss ∙ B. absorption loss ∙ C. resistive loss ∙ D. heat loss
Last Answer : A. power loss
Description : A dye absorbs a photon of wavelength `lambda` and re`-` emits the same energy into two phorons of wavelengths `lambda_(1)` and `lambda_(2)` respective
Last Answer : A dye absorbs a photon of wavelength `lambda` and re`-` emits the same energy into two phorons of wavelengths ` ... 2))/((lambda_(1)+lambda_(2))^(2))`
Description : Silica (pure glass) fibers are used because of their low intrinsic material absorption at the wavelengths of operation. This wavelength of operation is between two intrinsic absorption regions. What are these two regions called? What are the wavelengths of operation for these two regions?
Last Answer : Ultraviolet absorption region (below 400 nm) and infrared absorption region (above 2000 nm).
Description : A substance emits energy which is detected as a line emission in the visible region using a spectroscope. The origin of this energy is (a) Vibrational energy of the molecules (b) Rotational energy of the molecules (c) Energy of orbital electrons (d) Energy of protons in the nucleus.
Last Answer : Ans:(c)
Description : A radioactive substance does not undergo any change (in mass or charge) during – (1) ganuna-emission (2) oxidation (3) alpha-emission (4) beta-emission
Last Answer : (1) ganuna-emission Explanation: Gamma-rays do not carry any charge. These rays do not have any mass and hence can not be considered to be made up of particles.
Description : Emission of β-particles during radioactive decay of a substance is from (A) Innermost shell (B) Nucleus (C) Outermost shell (D) None of these
Last Answer : (B) Nucleus
Description : A radioactive substance does not undergo any change (in mass or charge) during (1) gamma-emission (2) oxidation (3) alpha-emission (4) beta-emission
Last Answer : gamma-emission
Description : The first emission line of Balmer series in `He^(+)` - spectrum has the wave no .in `(Cm^(_1))` (R-Rydberg constant)
Last Answer : The first emission line of Balmer series in `He^(+)` - spectrum has the wave no .in `(Cm^(_1))` (R-Rydberg constant ... )` C. `(5R)/(36)` D. `(R)/(6)`
Description : ____ is defined as any radiation of energy by means of electromagnetic wave. A. Emission B. Radiation C. Radio D. Broadcasting
Last Answer : A. Emission
Description : A modulation which does not follow the sine wave pattern, it produces undesirable harmonics such as spurious emission A. 0% modulated B. Over-modulated C. Unmodulated D. 100% modulated
Last Answer : B. Over-modulated
Description : Nucleic acid show strong absorption at one of the wavelength: (A) 280 nm (B) 220 nm (C) 360 nm (D) 260 nm
Last Answer : Answer : D
Description : Where do most re-absorption of substances occur?
Description : Light rays that are emitted simultaneously from an LED and propagated down an optical fiber do not arrive at the far end of the fiber at the same time results to ∙ A. intramodal dispersion ∙ B. pulse length dispersion ∙ C. modal dispersion ∙ D. wavelength dispersion
Last Answer : D. wavelength dispersion
Description : What parameter of light detector determines the range or system length that can be achieved for a given wavelength? ∙ a. Transit time ∙ b. Spectral response ∙ c. Dark current ∙ d. Responsitivity
Last Answer : ∙ b. Spectral response
Description : Of the following properties of a wave, the one that is independent of the other is its (a) Amplitude (b) Velocity (c) Wavelength (d) Frequency
Last Answer : Ans:(a)
Description : A travelling wave passes a point of observation where the time interval between successive crests is 0.2 s. Which of the following is then true? (a) The wavelength is 5 m (b) The wavelength is 0.2 m (c) The velocity of propagation is 5 m/s (d) The frequency of 5 Hz.
Description : What is wavelength and frequency of a wave?
Last Answer : The distance between two consecutive compressions or rarefaction is called wavelength. The number of waves in unit time is called frequency of wave.