Physics 09

          i = i₀ sin wt   . The  time  taken  by the  current to change from maximum value to it's rms value is 

    a.r^1/2

    b. r^-1/2

    c. n

    d. n-1

Ans:a

a. θ/10 lc

b. lc/10 θ

c. 10 θ /lc

d .θ /lc

Ans:d

21 . The angular dispersive power  dθ/d λ for a plane grating  is given by 

    a. n(a+b)/cosθ

    b. n cos θ/(a +b)

    c. (a+b) cos θ/n

    d. n/(a+b)cosθ

Ans:d

22. The wavelength of incident radiation be 5000A and number of lines on the grating 2620 to an inch. The number of orders visible in the grating spectra are

    a. 19

   a. λ1 λ2 =1

    b.  λ1= λ2

    c. λ1 <  λ2

    d.λ1 >  λ2

Ans:d

26. A beam of light is converging at a point on a screen. When a plane glass plate of thickness t and refractive index µ is placed in the path of beam, the point of convergence will get displaced from its position

    a. t( 1+ 1/µ)  nearer 

    b. t( 1- 1/µ) farther

    c.t( 1- 1/µ) nearer

    d.t( 1+ 1/µ) farther

Ans:b

27. A calcite crystal is placed over a dot on a piece of paper and rotated. On viewing through calcite , one will see

    a. A single dot

    b. two stationary dots

    c. two rotating dots

    d.One rotating about the other

Ans:d

28. If two interfering waves of wavelength  λ have a phase difference  of  ∏/2 degree . The path difference between them is 

    a. λ/4 

    b. λ/2

    c. λ

    d. 2 λ

Ans:a

29.The threshold wavelength that can cause photoelectric emission from a copper surface is 2760A . The work function of copper metal is

    a.  6 eV

    b. 4.5 eV

    c.3 eV

    d.1.5 eV

Ans:b

30. A beam of electrons , accelerated through 60 kV strike a target to produce X ray. The X ray frequency of emmission will be

    a. 1.45 X10^{16  Hz}

c. 2.45 X10^{18  Hz}

35. The life of an excited state of an atom is about  10^-8    sec. The minimum uncertainty in the determination of the energy of excited state is 

    a. 3.3 eV
    b. 3.3 X 10^-8  eV
    c. 6. 8 eV
    d. 6.8 X 10^-8  eV

Ans:b

36.  The ray which can penetrate into 20 cm thick iron sheet is 

c. 21 X10^{-31  kg}

Ans:d

39. The spin angular momentum for electron is 

    a. √(s(s+1)) ħ

    b. S ħ

    c. ħ

    d. ħ/2∏

Ans:a

40. Nucleus  Ne²²  after absorbing energy decay into 2 α  particles and a unknown nucleus. The unknown nucleus is 

    a. Nitrogen

    b. Carbon

    c. Boron

    d. Oxygen

Ans:a

41. The reaction which represent β decay is 

    a. ₀n¹  --- >  ₁¹p + _-1⁰ β 

    b.  ₁¹p -->  ₀n¹  + _-1⁰ β

    c. ₀n¹  --- >  ₁¹p + _-1⁰ β + ν^--

    d. ₁¹p -->   _-1⁰ β + ν^--

Ans:c

_{42.   The series limit wavelength of the Lyman series of Hydrogen atom emission spectra is} 

    a. 7300 A
    b. 3650 A
    c. 1822 A
    d. 911 A

Ans:d

43. The sign of charge carrier can be determined by utilising 

    a. Meissner effect

    b. Photo - electrical effect

    c. Hall effect 

    d. Piezo electric  effect

Ans:c

44. Total energy of a particle is exactly twice its rest energy, its speed is 

    a. 0.900 C
    b. 0.866C
    c. C
    d. 2C

Ans:b

45. Stroke and anti stroke lines are related with

    a. Raman Effect
    b. Zeeman Effect
    c. Compton Effect
    d. Stark Effect

Ans:a

46. The magnetic moment of an electron in nth orbit of hydrogen atom is 

    a. neh/∏m

    b. neh/2∏m

    c.neh/4m

    d.neh/4∏m

Ans:d

47. The maximum rectification efficiency of a halfwave rectifier is 

    a. 40.6 %
    b. 81.2 %
    c. 91%
    d. 100%

Ans:a

48. When the temperature of a semi conductor is increased , its resistance

    a. Increase
    b. Decrease
    c. Remain unchanged
    d. May increase or decrease

Ans:b

49. The output of XOR is given by

    a. AB+Ā.B^-

      ^{b. A+B}

    ^c. AB^-+Ā.B

    d. A.B

Ans:c

50 A common emitter amplifier uses BJT in the

    a. Saturation region
    b. cut off region
    c. inverted region
    d. active region

Ans:d

51. The mobility of charge carrier can be expressed in units of

    a. m2/volt-sec
    b. volt/m2-sec
    c. volt.sec/m2
    d. m2.sec/volt

Ans:a

52. A zener diode is used for

    a. rectification
    b. modulation
    c. detection
    d. voltage regulation

Ans:d

53. The gate which will have output 1 , is 

Ans:c

54. The depletion layer width of a p-n junction has maximum value in 

    a. Forward bias
    b. reverse bias
    c. zero bias
    d. a.c bias

Ans:b

55. The following truth table represents the logic gate :

56. A common emitter amplifier is designed with pnp transistor having  α = 0.99. The input impedence is 1k Ω  and  the load is 10 k Ω . The voltage gain will be 

    a. 9900
    b. 990
    c. 99
    d. 9.9

Ans:b

57. The semiconductor which comes in the category of direct band gap semiconductor is 

    a.  GaAs
    b. Si
    c. Ge
    d. Si-Ge combination

Ans:a

58. A silicon having intrinsic carrier concentration 1.5 X 10¹³  /cm3 is droped by a trivalent impurity of  10¹⁸ /cm3 concentration. After doping the number of electron in the sample will be

    a. 1.5 X 10¹³  /cm3
    b. 1.5 X 10³¹  /cm3
    c. 1.5 X 10^-5  /cm3
    d. 2.25 X 10⁸  /cm3

Ans:d

59. The correct expression for the critical velocity Vc is 

    a.  V­_c= k ή/ρ r

    b. V­_c= k ήρ /r
    c.  V­_c= k ρ r/ ή
    d. V­_c= k ρ/ή r

Ans:a

60. The true relation for a conservative force F is

    a. Δ.F = 0
    b. ΔXF = 0
    c. Δ2.F = 0
    d. Δ.(|F|) = 0

Ans:b

61. Tye radius of the orbit of a satellite is 16 times the radius of orbit of a geo stationary satellite. The period of the satellite is 

    a.  4 Days
    b.  8 Days
    c.  16 Days
    d.  64 days

Ans:d

62. If ρ is the density of material of a wire and  σ is the breaking stress, the greatest length of wire that can hang freely without breaking is 

    a.  2σ/ρ g
    b.  ρ/σ g
    c.  ρ g/2σ
    d.  σ/ρ g

Ans:d

63. Two soap bubbles of radii r1 and r2 (being r1>r2) combine to form a single bubble. The radius of common surface will be

    a.  r1.r2/r1-r2
    b.  r1.r2/r1+r2
    c.  r1-r2
    d.  r1+ r2

Ans:a

64. Plank's constant h has unit of 

    a.  Work
    b.  energy
    c.  linear momentum
    d.  angular momentum

Ans:d

65. The excess pressure inside a gas bubble of radius r completely dipped inside a liquid of surface tension T is 

    a.  4T/r
    b.  T/2r
    c.  2T/r
    d.  2Tr

Ans:c

66. A nanometer is equal to

    a.  10^-4  cm
    b.  10^-7  cm
    c.  10^-8 cm
    d.  10^-9  cm

Ans:b

67. Two cars having masses m1 and m2 move in circles of radii r1 and r2 respectively. If they complete the circles in equal time, the ratio of their angular speds (w1/w2) is 

    a.  m1/m2
    b.  r1/r2
    c.  m1r1/m2r2
    d.  1

Ans:d

68. A particles kinetic energy is n times its rest energy , its masses is 

    a.  m0
    b.  (1+n)m0
    c.  nm0
    d.  (1+1/n)m0

Ans:b

69. For the same cross sectional area and for the given load, the ratio of depression for the beam of a square cross section and that for circular cross section is 

    a.  3:∏
    b.  ∏:3
    c.  1:1
    d.  1:∏

Ans:a

70. The diameter of a ball is half that of another ball B . The ratio of these terminal speeds in water will be

    a.  1:2
    b.  1:1
    c.  1:4
    d.  2:1

Ans:c

71. The momentum of a photon of energy E is

    a.  Ec2
    b.  E/c
    c.  EC
    d.  E2c

Ans:b

72. The distance travelled by a freely falling body is proportional to 

    a.  mass of the body
    b.  time of fall
    c.  square of the time of fall
    d.  square of the acceleration due to gravity.

Ans:c

73. A cylinder fixed at one end is twisted by an angle ө on applying a couple C along the axis coinciding with the axis of the cylinder. The torsional rigidity is given by

    a.  C
    b.  ө
    c.  Cө
    d.  C/ө

Ans:d

74. The rest mass of an electron is m0. It is moving with velocity 0.8c . It mass becomes

    a.  0.8 m0
    b.  0.6 m0
    c.  1.25m0
    d.  1.66m0

Ans:d

75.The radius of gyration for a solid sphere of radius r rotating about it's tangential axis is 

    a.  √(2/5) r
    b.  √(3/5) r
    c.  √72/5) r
    d.  r

Ans:c

76. A jet engine works on the principle of conservation of 

    a.  energy
    b.  mass
    c.  linear momentum
    d.  angular momentum

Ans:c

77. photon obey

    a.  Maxwell Boltzman Statitics
    b.  Fermi Dirac Statistics
    c.  Bose Einstein Statistics
    d.  None of a , b or c

Ans:c

78. The coefficient of performance β of a refrigerator is

    a.  β = ή /(1- ή)
    b. β =ή
    c.  β = (1-ή)/ή
    d.  β = ή /(1+ ή)

Ans:c

79. the relation between coefficient of diffusion D and coefficient of viscosity is 

    a.  D=ρή 
    b. D=ή /ρ
    c.  D=ή Cv
    d.  D=ή /Cv

Ans:c

80. Two rods of length l1 and l2 are made of materials whose coefficients of linear expansion are  α1 and α2. If the difference between two lengths is independent of temperature 

    a.  l1/l2 = α2/α1
    b. l1/l2 = α1/α2
    c.  l₂² α₁ = l₁² α₂
    d.  α₁²/ α₂²= l₁^/l₂

Ans:a

_{81. The molecules of a gas have f degree of freedom then  the ratio r of two specific heats of the gas Cp/Cv is given by}

    a.  r = (1+2f)/f
    b.  r  = 1+f/2
    c.  r =3/2+f/2
    d.  r= 1+2/f

Ans:d

82. In carnot cycle the adiabatic process takes place

    a.  Once
    b.  twice
    c.  thrice
    d.  not a single time even

Ans:b

83. The mean kinetic energy of one gm mole of oxygen at 27 oc is

    a.  3.739 J
    b.  373.9 J
    c.  37.39 J
    d.  3739 J

Ans:c

84.If the pressure and temperature of an ideal gas is doubled, the volume is halved , the number of molecules of the gas

    a.  remain constant
    b.  becomes two times
    c.  become half
    d.  become four times

Ans:a

85. The concept of internal energy is obtained from

    a.  Zeroth law of thermodynamics
    b.  first law of thermodynamics
    c.  second law of thermodynamics
    d.  third law of thermodynamics

Ans:b

86. The relation between the pressure P and translational kinetic energy E of an ideal gas , is given by

    a.  E = 1/2 PV
    b.  E = 3/2 PV
    c.  E =  PV/2T
    d.  E = 3/2 p2V

Ans:b

87. Considering the emission of radiations from the Sun's surface like a blackbody emission at 6000 K and value of weins constant as 0.288 cm-K , the wavelength , for which light from the sun will have maximum intensity is

    a.  4800 A
    b.  3600 A
    c.  2880 A
    d.  6000 A

Ans:a

88. In a vander waals gas Joule - Thomson expansion produces heating only for

    a.  T> 2a/Rb
    b.  T<2a/Rb
    c.   T = 2a/Rb
    d.  T = a/Rb

Ans:b

89. Efficiency of an ideal heat engine is 0.75. If the temperature of the sink be 10 oC, the temperature of the source must be

    a.  40  ^oC 
    b.  400   ^oC
    c.  859  ^oC
    d.  859   ^oK

Ans:d

90. The value of solar constant is

    a.  2 cal cm-2 min-1
    b.  2 cal m-2 s-1
    c.  2 J m-2 S-1
    d.  2 J cm-2 min-1

Ans:a

91. The maxwell relation in thermodynamics that can be derived from enthalpy is

    a.   (ӘT/ӘV)s=- (ӘP/ӘS)v
    b.   (ӘT/ӘP)s= (ӘV/ӘS)p
    c.   (ӘP/ӘT)v=  (ӘS/ӘV)T
    d.  (ӘV/ӘT)v=- (ӘS/ӘP)T

Ans:b

92. Gibbs function G and Helmholtz function H may be expressed as

    a.  G = PV/H
    b.  G = H/PV
    c.  G = H -PV
    d.  G = H + PV

Ans:c

93. Number of possible modes of vibration between frequency range  ν and ν + dν per unit volume is 

    a.  nhν dν
    b.  8∏dν/ C2
    c.  8∏νdν/ C4
    d.  8∏ν2dν/ C3

Ans:d

94. The rms speed of oxygen molecules at room temperature is 500 m/s . The r.m.s. speed of hydrogen molecules at the same temperature as above is

    a.  750 m/s
    b.  2000 m/s
    c.  1000 m/s
    d.  1500 m/s

Ans:b

95. A whistle producing sound og 450 Hz is moving at speed 33 m/s towards a stationary listener. The speed of sound in air is 330 m/s. The frequency heard by the listener is 

    a.  409 Hz
    b.  429 Hz
    c.  500 Hz
    d.  517 Hz

Ans:d

96. An alternating voltage of 1 Volt and frequency 10⁵ sec-1 is applied in a LCR circuit of series arrangement. If value of R is 2 ohm and value of L is 0.5 mH, then for resonance , the value of capacitor C should be

    a.  5 X 10^-9  Farad
    b.  4 X 10^-9  Farad
    c.  3 X 10^-9  Farad
    d.  1 X 10^-9  Farad

Ans:a

97. The power in an alternating current circuit is measured by

    a.  I₀²/R
    b.  I_rms²/R
    c.  V_rms I _rms cos Ф
    d.  V_rms I _rms 

Ans:c        

_{98.  The equation , which represents wave travelling along negative Y axis is} 

    a.  x= A cos (-ky+wt)
    b.  x= A sin (ky+wt)
    c.  y= A sinky cos wt
    d.  x= A cos ky sin wt

Ans:b

99. The vibration of a string fixed at both ends are described by the equation 

y= 5 cm  sin∏x/2  sin 100 ∏t 

If the length of the string is 16 cm, the number of loops formed in vibration shall be

    a.  4
    b.  8
    c.  12
    d.  16

Ans:

100. A stationary wave is represented by

y= 10  cos 2∏x/5  sin 80 ∏t where y and x are in meters and t in seconds. The wavelength of the wave is 

    a.  80 meter
    b.  10 meter
    c.  5 meter
    d.  2 meter

Ans:c

101. The frequency of oscillation of a diatomic molecule in terms of force constant K and reduced mass µ, is given by

    a.  2∏√(µ/K)
    b.  2∏√(K/µ)
    c. ( 1/2∏)√(µ/K)
    d. ( 1/2∏)√(K/µ)

102. Medical use of ultrasonic wave is in

    a.  CAT Scan
    b.  MRI
    c.  Sonography
    d.  Angiography

Ans:c

103. A particle executing SHM with frequency f. The oscillating frequency of its kinetic energy is

    a.  2f
    b.  f/2
    c.  f
    d.  4f

Ans:a

104. In a transverse progressive wave of amplitude A , the maximum particle velocity is four times of wave velocity. The wavelength of the wave is

    a.  ∏A/4
    b.  ∏A/2
    c.  ∏A
    d.  2∏A

Ans:b

105. The quality factor meant for sharpness of resonance LCR electrical circuit is

    a.  wL/R
    b.  wL/C
    c.  wC/R
    d.  wR/L

Ans:a

106. High frequency electromagnetic vibration can be converted into high frequency mechanical vibration by utilizing 

    a.  Piezoelectric effect only
    b.  Magnetostriction effect only
    c.  Magnetostriction effect and Piezoelectric effect both.
    d.  Kerr effect

Ans:c

107. The differential equation that describe damped mechanical oscillation is

    a.  M d²x/dt² + R_m dx/dt =0
    b.  M d²x/dt² + R_m dx/dt + sx=0
    c.  d²x/dt²  + sx =0
    d.  R_m d²x/dt² + s/M x= 1/M dx/dt

Ans:b

108. For a complex harmonic wave , the necessary conditions are

y= 2a fro t = 0 to t =T/2

and y = 0 for t = T/2 to t= T the complex wave is

    a.  Rectangular wave
    b.  Sawtooth Wave
    c.  Triangular wave
    d.  Sine wave

Ans:a

109. If the density of aluminium is 2600 kg/m3 and its Young modulus is 7.8 X10¹⁰  N/m2 , the speed of sound in aluminium will be

    a.  340 m/s
    b.  3000 m/s
    c.  5477 m/s
    d.  6431 m/s

Ans:c

110. A particle on a string execute simple harmonic motion. When particle is at x=x_{max/2 , the speed of the particle  Vx  is} 

    a.  Vx = V_max/2
    b.  Vx = V_max
    c.  Vx = V3/2 V_max
    d.  Vx = 1/√2 V_max

Ans:c

_{111 A pipe open at both ends produces a note of frequency f1. when it  is  kept in water with 3/4 of its length in water it produces  a note of frequency f2. The ratio f1/f2 is}

    a.  3/4
    b.  4/3
    c.  2/1
    d.  1/2

112. Two waves of same amplitude 3A and having harmonic  nature with same phase and frequency are superimposed. The ratio of maximum and minimum intensities of  the resultant is

    a.  36:0
    b.  9:0
    c.  9:3
    d.  6:0

113. Flux Ф in a closed circuit of resistance 20 ohm varies with time according to 

Ф = 6 t² -5t +1  the magnitude of the induced current at t=0.25 second is 

    a.  1.2 A
    b.  0.8 A
    c.  0.6 A
    d.  0.1 A

114. The electric potential energy of a system of two positive point charge of 1 µC each placed in air at a distance of one meter apart

    a.  9 X  10^-3joule
    b.  1 X  10^-3joule
    c.  1 joule
    d.  Zero

115. Lenz's law is a consequence of the law of conservation of

    a.  Charge
    b.  mass
    c.  momentum
    d.  energy

116. Two capacitor of 4 µ F and 12 µ F are connected in series and the charges on the combination is 18 µC. The energy of the system will be 

    a.  48 X  10^-12joule
    b.  54 X  10^-6joule
    c.  48 X  10^-6joule
    d.  54X  10^-12joule

117. The electric field due to a dipole at a distance x from it is proportional  to

    a.  1/x
    b.  1/x2
    c.  1/x4
    d.  1/x3

118. Two thin long parallel wires separated by a distance b are carrying a current of i ampere each. The magnitude of the force per unit length exerted by one of the wire on  the other is

    a.  µ₀ i²/b²
    b.  µ₀ i²/2∏b
    c.  µ₀ i/2∏b
    d.  µ₀ i/2∏b²

119. The magnetic susceptibility  χ of paramagnetic material varies with absolute temperature T as 

    a.  χ  ∞ T
    b.  χ  ∞ 1/T
    c.  χ  ∞ e^T 
    d.  χ = constant

120. In The thevenin's equivalent circuit the Thevenin voltage equal to

    a.  Short circuit terminal voltage
    b.  Open circuit terminal voltage
    c.  emf of battery nearest to terminal
    d.  net voltage available in the circuit.