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Q.1 If Ro is the radius of the first (n = 1) orbit in a hydrogen atom, the radius of the fourth (n = 4) orbit is given by

a) 16Ro

b) 4Ro

c) Ro/4

d) Ro/16

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Q.2 Potential energy per unit volume u of a strained wire is:

a) Stress x Strain

b) Stress x Strain/4

c) Stress x Strain/2

d) 3 x Stress x Strain/4

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Q.3 Two lenses have dispersive power in a ratio of 2:3 these glasses are used to make an achromatic lens of focal length of 20 cm the value of focal lengths of two lenses are:

a) F1 = 5 cm, F2 = -10 cm

b) F1 = -10 cm, F2 = 10 cm

c) F1 = 6.67 cm, F2 = -10 cm

d) F1 = 10 cm, F2 = -10 cm

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Q.4 A capacitor with air between its plates has a capacitance of 8 micro Farad. Its capacitance on introducing a dielectric with a dielectric constant of 6 between its plate is:

a) 48 uF

b) 40 uF

c) 16 uF

d) 32 uF

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Q.5 For a vendor was gas the inversion temperature at low pressure is:

a) 27a/bR

b) 2a/Rb

c) ab/8R

d) a/8Rb

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Q.6 The wavelength of K alpha x-ray line of an element of atomic number Z = 11 is λ. the wavelength of K alpha line of another element of atomic number Z is λ then Z is:

a) 11

b) 44

c) 6

d) 4

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Q.7 The ratio of most probable speed and the average speed of a gas enclosed in a vessel is:

a) √兀/4

b) 1

c) 2/√兀

d) √兀/2

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Q.8 A rectangular glass plate of refractive index 1.5 is used as a polarizer the corresponding polarising angle will be:

a) 43.7 degree

b) 33.7 degree

c) 56.3 degree

d) 23.4 degree

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Q.9 When the plate voltage applied to a diode valve is changed from 48 volts to 50 volts, the plate current increases from 60 mA to 70 mA what is the dynamic plate resistance of the diode?

a) 200 ohm

b) 180 ohm

c) 150 ohm

d) 120 ohm

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Q.10 Viscosity of a gas is due to the transport of

a) Momentum

b) Energy

c) Mass

d) None of these

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Q.11 When the current in a coil changes from 8 A to 2 A in 3 x 10-3 s. The EMF induced in the coil is 2 V the self-inductance of the coil is:

a) 1mH

b) 5 mH

c) 20 mH

d) 10 mH

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Q.12 According to Planck's the average energy of an oscillator with frequency v (nu) and its internal energy multiples of

a) kT

c) 3kT/2

d) 0

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Q.13 A dipole is formed by two charges of 5 uC and- 5 uC at a distance of 8 mm. Find the electric field

i) at a point 25 cm away from the dipole center at its axis and

ii) at a point 20 cm away on a line perpendicular to the axis and passing through its center.

a) 6 x 106N/C, 4.5 x 104N/C

b) 4.6 x 104N/C, 4.5 x 104N/C

c) -4.6 x 104N/C, 4.5 x 104N/C

d) 4.6 x 104N/C, 6 x 106N/C

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Q.14 Compute the magnetic induction in the air at a point 10 cm from a long straight wire carrying a current of 20 A:

a) 3 x 10-5 T

b) 4 x 10-5 T

c) 5 x 10-5 T

d) 6 x 10-5 T

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Q.15 The shape of the Lissajous figures depends on:

a) the amplitude of the superposing Waves

b) frequencies of superposing waves

c) the phase difference between the supervising waves

d) all of the above

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Q. 16 For µ0 = 1.544 and µe = 1.544 and λ = 6500 Å, the thickness of a quarter wave plate is

a) 10.0 µm

b) 11.6 µm

c) 0.25 µm

d) 0.28 µm

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Q.17 The displacement current arises due to:

a) positive charges only

b) negative charges only

c) both positive and negative charges

d) time-varying electric field

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Q.18 A block of Steel heated to 100 degrees Celsius is left in a room to cool which of the following curve shown in figure represents correct behaviour:

a) A

b) B

c) C

d) None

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Q.19 The streamline flow of an incompressible and non-viscous liquid is described by:

a) Boyle's law

b) Poiseuille's law

c) Archimedes principle

d) Bernoulli's principle

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Q.20 In a young's double slit experiment the slit separation is 0.12 mm the wavelength of light used is 5893 Å and the interference pattern is observed on a screen 1 m away the separation between successive bright fringes will be:

a) 6.50 mm

b) 5.50 mm

c) 4.91 mm

d) 4.50 mm

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