## Articles Posted in the " Radiation " Category

• ### 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   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 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  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 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 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 ( […]

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 […]