Articles Posted in the " Radiation " Category

  • Mcq ON RADIATION EXCHANGE

    Mcq ON RADIATION EXCHANGE

    Mcq ON RADIATION EXCHANGE  Shape factor F12 between two bodies depends on the (a) Shape and size of the two bodies (b) Shape and size of the bigger body (c) Shape, size and orientation of the bigger body (d) None ANS:(d) Shape factor F12 between two bodies depends on the (a) Shape and size of […]


  • mcq: Radiation

    mcq: Radiation

    mcq: Radiation   Plank’s law gives the radiation flux for a (a) A single wavelength (b)  Two wavelengths ( c) Three wavelengths (d) None ANS: (a) Plank’s law gives the radiation flux for a (a) A Black body (b)  A Grey body ( c) All types of bodies (d) None ANS: (a) Stefan’s Boltzmann law is for […]


  • Question bank-Radiation

    Question bank-Radiation

    Question bank-Radiation RADIATION 2 MARK OBJECTIVE QUESTIONS According to Kirchoff’s law, Radiated heat is proportional to the fourth power of absolute temperature Emissivity is equal to absorbtivity Emissive power depends on absolute temperature None Ans: (b) All the radiations from a black body are Reflected Transmitted Partly absorbed and partly reflected None Ans: (d) According […]


  • Interview Short Question Answers on Radiation 

    Interview Short Question Answers on Radiation 

     Interview Short Question Answers on Radiation  Q.Basic Definitions in Radiation —–Absorbtivity, Reflectivity, transmissivity and Emissivity  Absorptivity, α Absorptivity is the ratio of absorbed radiations to the incident radiations on the surface. Symbol of absorptivity is ‘α’. It has no units. α ≤ 1. 2.  Reflectivity, ρ Reflectivity is the ratio of reflected radiations to the […]


  • Laws of Radiations

    Laws of Radiations

    Laws of Radiations PLANCK’S LAW OF MONOCHROMATIC EMISSIVE POWER It is relation for the emissive power (radiation flux) of a black body for one particular wavelength λ and is given by the following relation (Eλ)b=c1λ-5/ (ec2/λT –1)                                     W/m2 Where λ is any wavelength c1  and c2 are constants c1 =0.374 x 10-15   Jm2/s c2=1.4388 x […]


  • Heat transfer: radiation basics

    Heat transfer: radiation basics

    Heat transfer: radiation basics 1. DEFINITION OF A DIFFUSED SURFACE: It is a surface from which directions of emitted, reflected and incident radiations are unknown or is unpredictable. 2.DEFINITION OF 1 PHOTON: Energy carried by one EMR. Since different EMR are there in one type of rays, therefore 1 photon is different in one type ( […]


  • radiation: Basics

    radiation: Basics

     radiations: basics  1. FACTS ABOUT RADIO WAVES: Radio waves with λ= 3000 to 300 m, TV waves with λ= 300 m to 30 m, FM waves with λ = 30 m to 3 m, mobile phone waves with λ= 3m to 30 cm, Microwaves with λ = 30 cm to 0.3 cm, Waves from remote with […]


  •  Short Interview Question Answers on Radiation 

     Short Interview Question Answers on Radiation 

     Short Interview Question Answers on Radiation    Q. State the Boltzmann Law of radiation heat transfer. Stefan–Boltzmann law It is a law for a black body. It gives the total emissive power of a black body per unit area per unit time. This emissive power is proportional to the fourth power of the ABSOLUTE temperature. Thus […]


  • Short Interview Question Answers: Radiation

    Short Interview Question Answers: Radiation

     Short Interview Question Answers: Radiation  Q.which color has the lowest and highest frequencies? Red light is the lowest frequency of visible light and violet has the highest frequency. we see heated objects emit first red light as they get just hot enough to radiate in the visible range, and then orange, yellow, green, blue, and […]


  • * Short Interview Question Answers on Radiation

    * Short Interview Question Answers on Radiation

     Short Interview Question Answers on Radiation  Q  What is an opaque body?  A body which has zero transmissivity (τ=0). Or α + ρ=1. Solids normally do not transmit radiations and hence are opaque. Q  What is a white body?  A body which zero absorbtivity as well as zero transmissivity. It reflects the entire radiations. Mathematically      […]