GATE XE topic:engineering-sciences PYQs & Answers — Page 149

Questions 1481–1490 of 1772. Imported answers require independent review unless marked reviewed.

The atoms in a gas laser have two energy levels such that a transition from the higher to the lower level releases a photon of wavelength 500 nm. If 7 × 10²⁰ atoms are pumped into the upper level with 4 × 10²⁰ atoms in the lower level, the amount of energy released in a single pulse is __________ Joules (give answer up to 2 decimal places)

(Given: Planck’s constant, h = 6.6 × 10⁻³⁴ J s; speed of light, c = 3 × 10⁸ m s⁻¹)

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The speed of an electron is measured to be 300 m s⁻¹ with an uncertainty of 0.01%. The fundamental accuracy with which the position of the electron can be determined simultaneously with the speed in the same experiment is __________ mm (give answer up to 2 decimal places)

(Given: Planck’s constant, h = 6.6 × 10⁻³⁴ J s; mass of electron = 9.1 × 10⁻³¹ kg)

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When 3 identical non-interacting spin ½ particles are put in an infinite potential well, the ground state energy of the system is 18 meV. If instead, seven particles are put inside the potential well, the new ground state energy is ________ meV.

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If the value of the integral (I) is 4, the value of the constant b is __________ (give answer up to 2 decimal places).

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X-ray diffraction pattern is obtained from FCC polycrystalline aluminum (lattice parameter = 0.405 nm) using Cr-Kα radiation of wavelength 0.229 nm. The maximum number of peaks that can be observed in the pattern is __________.

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The planar atomic density in the (110) plane of a BCC iron crystal is __________ nm⁻² (give answer up to 2 decimal places)

(Given: lattice parameter of iron is 0.287 nm)

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Mild steel is carburized at 1300 K for 1 hour to obtain a certain case depth. Keeping the time as 1 hour, the case depth can be doubled by increasing the temperature to __________K (round off to the nearest whole number)

(Given: Activation energy Q = 148 kJ mol⁻¹, Gas constant, R = 8.314 J mol⁻¹ K⁻¹)

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A thin cylinder (thickness,

and diameter,

) with closed ends is subjected to an internal pressure,

. The ratio of hoop stress to longitudinal stress developed in the wall of the cylinder is

Your answerChoose one option.

1:4

1:2

1:1

2:1

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A steel rod is fixed at one end and free at the other end. The coefficient of thermal expansion of the steel is

, and modulus of elasticity is

. If the temperature of the rod is increased by

then the stress and strain developed in the rod are respectively

Your answerChoose one option.

zero,

, zero

zero, zero

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The effective lengths of the columns with ideal boundary conditions shown in Case-I, Case-II, and Case-III are respectively

Diagram for Engineering Sciences question 3

Your answerChoose one option.

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GATE XE topic:engineering-sciences PYQs

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21

Question 22

Question 1

Question 2

Question 3