Soluti-On

(a) AND  (b) NOR  (c) NAND  (d) OR Ans : (d) OR

(a) 45  (b) 50  (c) 55  (d) 60 Ans : (c) 55

(a) 0.1  (b) 0.66  (c) 0.75  (d) 0.98 Ans: (d) 0.98

 (a) 0.1 mA  (b) 0.2 mA  (c) 0.3 mA  (d) 0.4 mA Ans: (b) 0.2 mA

 (a) A+B  (b) A⊕𝐵  (c) 𝐴 + 𝐵  (d) A.B Ans: (b) A⊕𝐵

(a) diffusion  (b) recombination  (c) photovoltaic action  (d) carrier flow Ans: (c) photovoltaic action

(a) junction is reversed biased  (b) depletion layer widens (c) holes and electrons recombine  (d) junction becomes hot Ans: (c) holes and electrons recombine.

 (a) in the emitter  (b) in the collector  (c) in the base  (d) through CB junction  Answer:- (a) in the emitter

Law of equipartition : For a gas in thermal equilibrium at temperature T, the average energy for molecule associated with each quadratic term is 1/2 kbt

For monoatomic gas containing N number of atoms at temperature T there are 3 translational degrees of freedom. Average energy per atom isk and the total internal energy per mole is E= 3/2 kNT .. Molar specific heat at constant volume is Cv= dE/ dT = 3/2 Nk  Since Cp-Cv=R , Cp=Cv+R=3/2R+R Cp =5/2R Gama= Cp /Cv = 5/2 R/ 3/2R= 5/ 3

 Amount of heat radiated depends upon following:  a) The absolute temperature of body. b) Nature of body: polished or rough surface. c) Surface area of body.  d) Time duration for which body emits radiation.

 a) At high pressure, the molecules are very close to each other. The short range repulsive forces start operating and molecules behaves as small spherical particle. The net volume of gas molecules cannot be ignored with respect to available volume of motion. Therefore very less volume is available for motion. b) At very low temperature, the molecular motion becomes slowand the molecules are attracted to each other due to attractive force. Because of these two reasons, there is deviation of real gas from ideal gas behaviour.

Amount of heat radiated depends upon a) The absolute temperature of body. b) Nature of body: polished or rough surface. c) Surface area of body. d) Time duration for which body emits radiation.

Characteristics of perfectly black body: i) A perfectly black body absorbs all the radiant energy incident on it. So coefficient of absorption is unity whereas coefficient of transmission and coefficient of reflection is zero. ii) When a perfectly black body is heated it emits radiations of all possible wavelengths at that temperature. iii) Wavelength range of perfectly black body is independent of material. It depends upon temperature of the body.

 A perfectly black body: A body which can absorb all the radiant heat incident on it is called perfectly black body. 1. It consists of doubled walled hollow sphere having small aperture through which heat energy enters. 2. It has conical projection diametrically opposite to the aperture to avoid reflection along same path. 3. The inner surface of sphere is coated with lamp black and outer surface is nickel polished. 4. The space between two walls is evacuated to minimize heat loss by conduction and convection.The radiant energy entering the sphere suffers multiple reflections. 5. During each reflection 98 % of heat is absorbed so that within few reflections all the radiant heat i absorbed by sphere.

 A body which can absorb all the radiant heat incident on it is called perfectly black body. Properties:  1) A perfectly black body absorbs all the quantity of radiant heat incident on it. 2) Coefficient of absorption = 1 3) Coefficient of emission = 1 (i.e.) it is best emitter of heat energy. 4) Coefficient of reflection and transmission = 0

Diathermanous substances: Substances through which heat radiations can pass are called diathermanous substances. e.g. glass,quartz, hydrogen, oxygen, dry air, sodium chloride etc. for these substances t = 1.   Athermanous substances: Substances through which heat radiation can not pass are called athermanous substances. e.g. wood, water, iron, copper etc For these substances t=0.

 Degrees of freedom of any gas depends upon i) Atomicity of the gas i.e. whether the gas is monoatomic,diatomic,triatomic.   ii) Geometric shape of the gas molecule i.e. whether the gas is rigid, non rigid or linear, non linear.  iii) Temperature of gas.

 When the gas is heated, the molecules of the gas acquire the energy and their r.m.s. velocity increases. According to kinetic theory of gases, the r.m.s. velocity of gas is Vms= √3RT /M i.e. Vrms ∞ √T Thus increase in Vrms, increases the temperature of gas.

 i) The motion of solid object can be well described with the help of Newton's law of motion. ii) Similarly the motion gas enclosed in a container can be described by macroscopic state parameters like pressure, volume, temperature. iii) However gas molecules are always in state of random motion, it is difficult to understand the behaviour of gas in terms of motion of a single molecule. iv) The number of moleccules in the gas is so large that motion of indivual molecule cannot be related with pressure, volume, temperature. Hence it is necessary to make certain assumptions, while stdying behaviour of gas.

 For nitrogen. M-28, m= 7 (given)  n=m/M=7/28=1/4 Ideal gas equation is PV = nRT PV = 1/4 RT