GATE IN 2020 Paper 1 — page 19

Questions 55–57 of 65. Imported answers require review unless explicitly marked reviewed.

A metallic strain gauge of resistance

with a gauge factor of 2 is bonded to a structure made of a metal with modulus of elasticity of 200 GN/m

. The value of

is 1 kΩ when no stress is applied.

is a part of a quarter bridge with three identical fixed resistors of 1 kΩ each. The bridge is excited from a DC voltage of 4 V. The structure is subjected to a stress of 100 MN/m

. Magnitude of the output of the bridge (in mV, rounded off to two decimal places) is ____

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A laser beam of 10 mm beam diameter is focused onto an optical fibre using a thin biconvex lens as shown in the figure. The refractive index of the lens is 1.5. The refractive indices of the core and cladding of the fibre are 1.55 and 1.54 respectively. The minimum value of the focal length of the lens to attain the maximum coupling to the fibre (in mm, rounded off to one decimal place) is ____

Diagram for Instrumentation Engineering question 46

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As shown in the figure, a slab of finite thickness

with refractive index

, has air (

) above and below it. Light of free space wavelength 600 nm is incident normally from air as shown. For a destructive interference to be observed at R, the minimum value of thickness of the slab

(in nm) is ____

Diagram for Instrumentation Engineering question 47

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2020 · Paper 1

Question 45

Question 46

Question 47