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 : Sodium vapour lamps glow with yellow colour. This is due to - (1) sublimation of sodium to emit yellow colour (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the ... (3) the low ionisation energy of sodium (4) its ability to absorb all other colours except yellow
Last Answer : (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum Explanation: Sodium Vapour Lamps glow with yellow colour due to the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum.
Description : Sodium vapour lamps glow with yellow colour. This is due to (1) sublimation of sodium to emit yellow colour (2) the emission of excess energy absorbed by sodium atoms, in the yellow region of the ... (3) the low ionisation energy of sodium (4) its ability to absorb all other colours except yellow
Last Answer : the emission of excess energy absorbed by sodium atoms, in the yellow region of the spectrum
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 : Stars appear twinkling because of ......... of light. (1) Reflection (2) Scattering (3) Emission (4) Absorption
Last Answer : Scattering
Description : Now-a-days yellow lamps are frequently used as street lights. Which of the following gases is used in these lamps? (1) Sodium (2) Neon (3) Hydrogen (4) Nitrogen
Last Answer : (1) Sodium Explanation: A sodium-vapor lamp is a gasdischarge lamp that uses sodium in an excited state to produce light. There are two varieties of such lamps: low pressure and high. ... High-pressure sodium lamps have a broader spectrum of light but poorer colour rendering than other types.
Description : Now-a-days yellow lamps are frequently used as street lights. Which of the following gases is used in these lamps ? (1) Sodium (2) Neon (3) Hydrogen (4) Nitrogen
Last Answer : Sodium
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
Last Answer : Ans:(d)
Description : Decrease in atomic number is observed during a)`alpha`-emission b)`beta`-emission c)positron emission d)electron capture
Last Answer : Decrease in atomic number is observed during a)`alpha`-emission b)`beta`-emission c)positron emission ... `-emission C. positron emission D. K-capture
Description : The decrease in the atomic number is not observed in case of (A) Electron capture (B) β-emission (C) α-emission (D) Positron emission
Last Answer : (B) β-emission
Description : In radioactive decay, the emission of an electron is characteristic of: w) Alpha decay x) Beta decay y) Gamma decay z) X-rays
Last Answer : ANSWER: X -- BETA DECAY
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 : Absorption of light of one wave length by a substance and the re-emission of light of greater wavelength is called?
Last Answer : Fluorescence
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 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 : Why do street lamps turn on and off?
Last Answer : I’ve never come across this phenomena… obviously I take it this is not just occurring at dawn and dusk…very odd…. hmmmmm
Description : Do you ever see street lamps go out?
Last Answer : I have heard it is a technique used to save energy.
Description : Sodium vapor Lamps glow with yellow Light. This is due to–
Last Answer : Sublimation of sodium to emit yellow colour
Description : Sodium vapor Lamps glow with yellow Light. This is due to
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 : Show diagrammatically the electron distributions in a sodium atom and a sodium ion and also give their atomic number. -Science
Last Answer : Atomic number of sodium (Z) =11 Mass number of sodium (A) = 23 Number of protons in the nucleus = 11 Number of neutrons in the nucleus =23-11 = 12 Number of electrons = 11 Electronic ... the electronic configuration is 2, 8(K, L). However, the number of protons and neutrons remains the same.
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 : Write various advantages of using high mast tower lighting viz a vIz Sodium lamps in circulating areas?
Last Answer : Ans. (i) Better illumination (ii) Vide area illumination (iii)where mass public movement (iv) Where loading & unloading of materials (v) At goods coaches & passenger coaches formation, checking and maintenance.
Description : The method used to produce electron emission in most vacuum tubes is known as ____________. A. photoelectric emission B. secondary electric emission C. cold cathodic electric emission D. thermionic emission
Last Answer : Answer: D
Description : State the different modes of electron emission in metal. Explain any two modes of emission.
Last Answer : Different modes of electron emission in metal - 1. Thermionic emission 2. Photo electric emission. 3. Field emission. 4. Secondary emission. Mode of Emission 1. Thermionic emission. ... (GaP) Application: Electron multiplier tubes, Special amplifying tubes, Computer memory tubes.
Description : In Rutherford's experiment involving the deflection of alpha particles by atomic nuclei, the fact that some of the alpha particles bombarding the thin gold foil were back-scattered, led to one of the ... its nucleus z) the nucleus of a gold atom occupies nearly the entire space of the atom
Last Answer : ANSWER: Y -- MOST OF THE MASS OF A GOLD ATOM IS IN ITS NUCLEUS
Description : When an atomic nucleus emits a beta particle, one of its neutrons disintegrates into one of the following set of particles. Does it disintegrate into: w) a positron and an electron x) a proton, an ... and an antineutrino y) a proton, an electron, and a positron z) a neutrino and an antineutrino
Last Answer : ANSWER: X -- A PROTON, AN ELECTRON AND AN ANTINEUTRINO
Description : An electron microscope gives higher magnification than an optical microscope, because: (1) It uses more powerful lenses (2) the velocity of electron is smaller than that of visible (3) the ... particles (4) the wavelength of electrons is smaller as compared to the wavelength of visible light
Last Answer : (4) the wavelength of electrons is smaller as compared to the wavelength of visible light Explanation: An electron microscope uses a beam of electrons to illuminate a specimen and produce a ... photons. Magnification is the process of enlarging something only in appearance, not in physical size.
Description : An electron microscope gives higher magnifications than an optical microscope because - (1) The velocity of electrons is smaller than that of light (2) The wavelength of electrons is smaller as ... have more energy than the light particulars (4) The electron microscope uses more powerful lenses
Last Answer : (2) The wavelength of electrons is smaller as compared to the wavelength of visible light Explanation: An electron microscope is a microscope that uses a beam of accelerated electrons as a spume ... a higher resolving power than a light microscope and can reveal the structure of smaller objects.
Description : An electron microscope gives higher magnifications than an optical microscope because : (1) The velocity of electrons is smaller than that of light (2) The wavelength of electrons is smaller as ... have more energy than the light particulars (4) The electron microscope uses more powerful lenses
Last Answer : The wavelength of electrons is smaller as compared to the wavelength of visible light
Description : An electron microscope gives higher magnification than an optical microscope, because : (1) it uses more powerful lenses (2) the velocity of electron is smaller than that of visible light (3) ... particles (4) the wavelength of electrons is smaller as compared to the wavelength of visible light
Last Answer : the wavelength of electrons is smaller as compared to the wavelength of visible light
Description : How are atomic emission spectra used to identify elements?
Last Answer : Atomic emission spectra are chracteristic for each element.
Description : How Are the atomic and mass number Affected by positron emission?
Last Answer : What is the answer ?
Description : The emission of an a-particle causes the resultant nucleus to have (A) More atomic weight and less atomic number (B) Less atomic weight and less atomic number (C) Less atomic weight and more atomic number (D) None of these
Last Answer : (A) More atomic weight and less atomic number
Description : What Molecular orbital interactions are not possible because the atomic orbitals have overlapping electron densities.?
Last Answer : Need answer
Description : A 15-year-old girl was seen by her family physician because of increasing lethargy. She had a recent history of the "flu". Biochemistry tests show that she has renal impairement. ... will likely develop a restrictive lung disease 5) She will probably improve with additional corticosteroid therapy
Last Answer : Answers-2 The findings point to focal segmental glomerulosclerosis (FSGS), which leads to chronic renal failure in half of cases. The lack of resolution with corticosteroid therapy and the progression to chronic renal failure is what sets FSGS apart from minimal change disease.
Description : Is there any research indicating that light therapy lamps help with vitamin D deficiency?
Last Answer : answer:The body produces Vitamin D from exposure to Ultraviolet rays, the problem is skin cancer. Instead take D3 capsules or other D supplements.
Description : In a three-phase electrical system, three ground detecting lamps are provided. If all three lamps REMAIN at half-brilliance when the ground detecting test switch is operated, ______________. A. there is a ... must be replaced C. there are no grounds present D. the light bulbs are of improper voltage
Last Answer : Answer: C
Description : What current is required to light two 75 watt lamps and one 40 watt lamp when connected in series to a 120 volt power source? A. 0.161 amperes B. 0.631 amperes C. 1.583 amperes D. 6.199 amperes
Description : An AC generator panel is fitted with both synchronizing lamps and a synchroscope. When the synchroscope pointer reaches the noon position, one synchronizing light is bright and the other is dark. This ... sequence is incorrect C. the phase sequence is correct D. the generator breaker may be closed
Last Answer : Answer: B
Description : The delay fuses are used for the protection of ________ . (a) motors (b) power outlet circuits (c) fluorescent lamps (d) light circuits
Last Answer : (a) motors
Description : Mercury is commonly used as a thermometric fluid rather than water because (1) specific heat of mercury is less than water (2) specific heat of mercury is more than water (3) mercury has greater visibility than water (4) density of mercury is more than the water
Last Answer : (3) mercury has greater visibility than water Explanation: One special kind of mercury-inglass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.
Description : On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because (1) Mercury is a metal (2) Density of mercury is greater than that ... is greater than its adhesion with glass (4) Cohesion of water is greater than its adhesion with glass
Last Answer : (3) Cohesion of mercury is greater than its adhesion with glass Explanation: When liquid is placed on a smooth surface like glass plate, the relative strengths of the cohesive and adhesive forces acting on ... and a surface are stronger, they will pull the liquid down, causing it to wet the surface.
Last Answer : Cohesion of mercury is greater than its adhesion with glass
Description : The blue colour of water in the sea is due to – (1) absorption of other colours except blue by water molecules (2) scattering of blue light by water molecules (3) reflection of blue light by impurities in sea water (4) reflection of blue sky by sea water
Last Answer : (1) absorption of other colours except blue by water molecules Explanation: Almost all sunlight that enters the ocean is absorbed, except very close to the coast. The red, yellow, and green ... to the absorption and scattering of light. The blue wavelengths of light are scattered, similar to the
Description : Fibre optics work on the principle of - (1) scattering of light (2) total internal absorption (3) total internal reflection (4) option rotation
Last Answer : (3) total internal reflection Explanation: An optical fibre is a cylindrical dielectric waveguide (non-conducting waveguide) that transmits light along its axis, by the process of total internal reflection.
Description : Fibre optics work on the principle of – (1) Scattering of light (2) Total internal absorption (3) Total internal reflection (4) Optical rotation
Last Answer : (3) Total internal reflection Explanation: An optical fiber (or optical fibre) is a flexible, transparent fiber made of glass (silica) or plastic, slightly thicker than a human hair. It ... science and engineering concerned with the design and application of optical fibers is known as fiber optics.
Description : The blue colour of water in the sea is due to (1) absorption of other colours except blue by water molecules (2) scattering of blue light by water molecules (3) reflection of blue light by impurities in sea water (4) reflection of blue sky by sea water
Last Answer : absorption of other colours except blue by water molecules
Description : Fibre optics work on the principle of (1) scattering of light (2) total internal absorption (3) total internal reflection (4) optical rotation
Last Answer : total internal reflection