University of Mumbai first-year engineering Semester I Applied Physics paper, December 2025, NEP 2020 scheme, with step-by-step solutions written with AI help and checked.
Mumbai University FE Sem 1 Applied Physics (BSC102) Question Paper December 2025
Written semester papers (NEP 2020 scheme): 60 marks and 2 hours for most first-year courses. Question 1 is compulsory, then any three of questions 2 to 6.
Sections
| Q.1 Attempt any five (compulsory) | 7 questions | |
| Q.2 (attempt any two of Q.2 to Q.5) | 3 questions | |
| Q.3 (attempt any two of Q.2 to Q.5) | 3 questions | |
| Q.4 (attempt any two of Q.2 to Q.5) | 3 questions | |
| Q.5 (attempt any two of Q.2 to Q.5) | 3 questions |
Chapters covered
Instructions
Solve on paper with a timer, then check against the solutions.
Q.1 Attempt any five (compulsory)
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Q.1 (a) Explain optical resonator in LASER?
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Q.1 (b) An optical fiber of core refractive index of 1.50 is to be clad to ensure that TIR will take place for a light ray with critical angle 85°. What minimum refractive index is allowed for cladding?
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Q.1 (c) Find the minimum thickness of soap film which appears dark (Wavelength [first digit partly illegible in the source scan; read as 5]896 A°) in reflection when light is incident normally on the film. Given refractive index of the film is 1.33.
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Q.1 (d) What do you mean Curl of vector. Write its significance.
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Q.1 (e) Write the properties of matter waves.
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Q.1 (f) The ground state energy of an electron in an infinite well is 1 eV. What will be the ground state energy if the width of the well is doubled?
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Q.1 (g) Define drift velocity and Mobility. Write its unit.
Q.2 (attempt any two of Q.2 to Q.5)
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Q.2 (a) List and briefly explain any two industrial applications of laser.
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Q.2 (b) Derive an expression for acceptance angle of a step index optical fiber.
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Q.2 (c) Obtain an expression for minimum thickness of anti-reflecting film.
Q.3 (attempt any two of Q.2 to Q.5)
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Q.3 (a) Find Curl of vector F (x2y + xy2z + 3x2z2) at point (1,-1,1)
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Q.3 (b) Derive the Schrodinger’s Time Dependent differential equation for matter waves
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Q.3 (c) Show that the intrinsic Fermi level lies in the middle of the band gap.
Q.4 (attempt any two of Q.2 to Q.5)
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Q.4 (a) Calculate electron and hole concentration in intrinsic silicon at room temperature if its electric conductivity is 4x10-4 mho/m. Given that mobility of electron is 0.14 m2/V-Sec mobility of holes is 0.04 m2/V-Sec.
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Q.4 (b) Derive the condition for maxima due to interference of light reflected from thin film of uniform thickness.
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Q.4 (c) Calculate velocity and de-Broglie wavelength of alpha particle of energy 1[unit prefix partly illegible in the source scan; read as k]eV. Given: mass of alpha particle as 6.68x10-27 kg.
Q.5 (attempt any two of Q.2 to Q.5)
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Q.5 (a) Explain the following terms in optical fiber: a) Total internal reflection b) Critical angle c) Acceptance angle d) Attenuation e) Numerical aperture.
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Q.5 (b) Deduce Maxwell’s second equation in differential and integral form.
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Q.5 (c) With the help of neat diagram, explain construction and working of He Ne laser.