Description : In the annihilation of matter the number of photons produced is a) One b) Two c) Three d) None
Last Answer : b) Two
Description : The reverse process of photo-electric effect is called: a) Annihilation of matter b) Compton effect c) Pair production d) X-rays
Last Answer : d) X-rays
Description : By the transition of inner shell electrons in heavy atoms, high energy photons are emitted which are a) gamma rays b) X-rays c) radio waves d) photon rays
Last Answer : b) X-rays
Description : An inkjet printer uses in its operation: (a) Positrons (b) Neutrons (c) An electric charge (d) Photons
Last Answer : (c) An electric charge
Description : Anungrounded antennanearthe ground a. acts as a single antenna of twice the height b. is unlikely to need a ground screen c. acts as anantennaarray d. must be horizontally polarized
Last Answer : c. acts as anantennaarray
Description : Which one of the following waves requires a material medium for their propagation? a) Light waves b) X– rays c) -rays d) Sound waves
Last Answer : d) Sound waves
Description : Thehigherthe index number a. the higher the speed of light b. the lower the speed of light c. has no effect on the speed of light d. the shorter the wavelength propagation
Last Answer : a. the higher the speed of light
Description : Electron can exist in the atom but outside the nucleus because a) speed of electron is equal to the speed of light b) speed of electron is more than speed of light c) speed of electron is less than speed of light d) None of these
Last Answer : c) speed of electron is less than speed of light
Description : If a material object moves with the speed of light ‘c’ its mass becomes a) equal to its rest mass b) Four times of its rest mass c) Double of its rest mass d) Infinite
Last Answer : d) Infinite
Description : A rod at rest appears to an observer just a mere point when he moves across it as speed, a) Equal to the speed of light b) Double the speed of light c) Three-fourth the speed of light d) None of the above
Last Answer : a) Equal to the speed of light
Description : How can photons move when at the speed of light there is no time for photons?
Last Answer : I guess as photon has no mass then time has no real meaning for it, however we do have mass so relative to us the photon does move? My head hurts…
Description : The energy associated with one photon of a light beam is proportional to one of the following. Is it proportional to: w) the intensity of the light source from which it came x) the number of photons in the beam y) the frequency of the photon z) the speed of the photon
Last Answer : ANSWER: Y -- THE FREQUENCY OF THE PHOTON
Description : Which one of the following particles travels at the speed of light? w) neutrons x) electrons y) photons z) muons
Last Answer : ANSWER: Y -- PHOTONS
Description : Are we on our way to self annihilation?
Last Answer : answer:I love your topic tag. :D Mankind has been through a lot. I don’t know if war and violence will destroy us since it’s happened for centuries and we still be kickin’, but the rate by which we destroy the vital resources we require for survival is another story altogether.
Description : What is an annihilation set ?
Last Answer : If two sets do not have any common elements, then those two sets are called mutually exclusive sets.
Description : X-rays can penetrate several ____ into a solid matter. a) millimeters b) meters c) centimeters d) kilometers
Last Answer : c) centimeters
Description : de Broglie’s relation for matter waves was experimentally verified by: a) Davisson b) Germer c) G.P. Thomson d) All the these
Last Answer : c) G.P. Thomson
Description : The concept of matter waves was introduced by a) Davisson and Germer b) de Broglie c) Einstein d) Schrodinger
Last Answer : b) de Broglie
Description : The presence of anti-matter was predicted by a) P.A.M Dirac b) Anderson c) Einstein d) Chamberlain
Last Answer : a) P.A.M Dirac
Description : Supersonic plane fly with the speed - (1) less than the speed of sound (2) of sound (3) greater than the speed of sound (4) of light
Last Answer : (3) greater than the speed of sound Explanation: The regimes of flight are subsonic, transonic, supersonic and hypersonic. Vehicles that fly at supersonic speeds are flying faster than the speed of sound. The speed of sound is about 768 miles per hour (1,236 kilometers per hour) at sea level.
Last Answer : (3) greater than the speed of sound Explanation: Supersonic travel is a rate of travel of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) ... this speed is approximately 344 m/s, 1,125 ft/s, 768 mph, 667 knots, or 1,235 km/h.
Description : The induced current in transformer which produced in the direction perpendicular to flux, is known as: a. Conventional current b. electronic current c. Perpendicular current d. Eddy current
Last Answer : c. Perpendicular current
Description : Eddy currents produced in the core of transformer are responsible for: a. heat loss b. Step up process c. Step down process d. induction phenomena
Last Answer : d. induction phenomena
Description : The induced emf is produced in a circuit due to: a. Initial magnetic flux b. final magnetic flux c. Change of magnetic flux d. constant magnetic flux
Last Answer : d. constant magnetic flux
Description : The output waveform produced due to time base generator in a CRO is a) saw tooth b) sinusoidal c) linear d) helical
Last Answer : a) saw tooth
Description : A solenoid has n turns and length l. If length is reduced to l/2 and turns are doubled then magnetic field B produced by it becomes equal to a) 2B b) 4B c) 1/2 B d) None of these
Last Answer : a) 2B
Description : Photoelectric electricity is produced directly from solar energy when which of the following are absorbed in a semiconductor to create an electric current? w) protons x) electrons y) neutrons z) photons
Last Answer : ANSWER: Z -- PHOTONS
Description : How is the speed of a DC motor varied?
Last Answer : To vary the speed of a DC motor we need a constant voltage power supply with a series POT resistor of higher watt rating. A Pulse Width Modulator (PWM) can be used.
Description : How is the speed of a 3-phase induction motor varied?
Last Answer : The speed of a normal 3-phase induction motor is a function of the frequency of the supply voltage. Changing the speed of such a motor hence requires building a 3-phase power frequency ... realised by using power MOSFETs (or IGBTs) capable of handling high voltages and fast switching speeds.
Description : If electron has to be confined in the nucleus, its speed would have to be greater than a) 1010 cm/s b) 1010 m/s c) 1020 m/s d) 1020 cm/s
Last Answer : b) 1010 m/s
Description : The speed of hydrogen electron in the nth orbit is given by vn = a) 2λke2 / nh b) 2πke2 / λh c) 2πke2 / nh d) 2πke2 / h
Last Answer : c) 2πke2
Description : Which one of the following physical quantities is independent of relativistic speed? a) Mass b) Length c) Time d) Charge
Last Answer : d) Charge
Description : A magnetic field acts on a charged particles so as to change its: a. speed b. energy c. direction of motion d. all of these
Last Answer : Only direction of motion will change ...it means velocity will change but speed same
Description : An α particle moves perpendicular to a constant magnetic field of strength 1.2 T in a circular path of radius 0.7 m. The speed of α particle in ms-1 is ______________ a) 2.7 × 107 b) 2.6 × 107 c) 3.2 × 107 d) 2.0 × 107
Last Answer : a) 2.7 × 107
Description : Which of the following quantities change when a proton moves at right angles to a magnetic field? a) Momentum b) Energy c) Speed d) All of these
Last Answer : a) Momentum
Description : EMDis best describe bywhich statement? a. 70percentofthe corediameter and70%ofthefiberNAshouldbe filled with light b.70 percent of the fiber diameter and 70% of the cone of acceptance should be filled with ... the output d.70 percent of the unwanted wavelengths should be attenuated by the fiber
Last Answer : a. 70percentofthe corediameter and70%ofthefiberNAshouldbe filled with light
Description : The termresponsivityasit appliesto a light detectorisbest described as a. the time required for the signal to go from 10 to 90 percent of maximum amplitude b.the ratio ofthediode output currentto ... of output current to output power d. the ratio of output current to input current
Last Answer : b.the ratio ofthediode output currentto opticalinputpower
Description : The claddingwhichsurroundsthe fiber core a. is used to reduce optical interference b. is used to protect the fiber c. acts to help guide the light in the core d. ensures that the refractive index remains constant
Last Answer : c. acts to help guide the light in the core
Description : The termcritical angle describes a. the point at which light is refracted b. the point at which light becomes invisible c. the point at which light has gone from the refractive mode to the reflective mode d. the point at which light has crossed the boundary layers from one index to another
Last Answer : c. the point at which light has gone from the refractive mode to the reflective mode
Description : Whichofthe followingterms describesthe reason thatlightisrefractedat different angles? a. Photon energy changes with wavelength b. Light is refracted as a function of surface smoothness c. The angle is determined partly by a and b d. The angle is determined by the index of the materials
Last Answer : d. The angle is determined by the index of the materials
Description : The termdispersion describestheprocessof a.separatinglightinto its componentfrequencies b. reflecting light from a smooth surface c. the process by which light is absorbed by an uneven rough surface d. light scattering
Last Answer : a.separatinglightinto its componentfrequencies
Description : Anincidentraycan be defined as a. a light ray reflected from a flat surface b. alight raydirectedtowardasurface c. a diffused light ray d. a light ray that happens periodically
Last Answer : b. alight raydirectedtowardasurface
Description : How does a tube light work?
Last Answer : It is well explained in Dennis T Hall When voltage is applied to the fluorescent lamp, here's what happens: ∙ The starter (which is simply a timed switch) allows current to flow through ... circuit contains a lot of current. The current either vaporizes the filaments or causes the bulb to explode.
Description : Laser is the acronym for a) Light Amplification by Stimulated Emission of Radiation b) Light Amplification by Spontaneous Emission of Radiation c) Light Amplified by Stimulated Emission of Radiation d) Light Amplification by Standard Emission of Radiation
Last Answer : a) Light Amplification by Stimulated Emission of Radiation
Description : Red Laser light has a wavelength of a) 630.8 nm b) 630 cm c) 632.8 nm d) 639.9 nm
Last Answer : c) 632.8 nm
Description : Lasers are used to produce a) Intense beam of visible light b) monochromatic beam of visible light c) coherent beam of visible light d) All of them
Last Answer : d) All of them
Description : In human flesh, the three light elements which predominate, and allow greater amount of incident X-rays to pass through them are a) oxygen, nitrogen , hydrogen b) oxygen, hydrogen, helium c) oxygen, hydrogen, carbon d) carbon, nitrogen, oxygen
Last Answer : c) oxygen, hydrogen, carbon
Description : Noble prize was awarded to De-Broglie for his work on particle nature of light in a) 1929 b) 1937 c) 1905 d) 1915
Last Answer : a) 1929
Description : Light waves can cause photoelectric emission in a) Metals b) Alkali metals c) Insulators d) None of the above
Last Answer : c) Insulators
Description : Relativistic velocity is of the order of, a) 15 1 of the velocity of light b) 20 1 of the velocity of light c) 10 1 of the velocity of light d) All the above
Last Answer : d) All the above