AMIE Section A Physics Question Paper April 2025 - ECourseFlix

Date: 18/11/2025

The Institution of Engineers, Bangladesh

AMIE (SEC. A OLD & NEW), (SEC. A NEW_CSE) EXAMINATION, APRIL 2025

Sub: Physics

Full Marks: 100

Time: 3 Hours

The figures in the margin indicate full marks. The symbols have their usual meaning. Assume reasonable data, if necessary.

There are SEVEN questions in this paper. Answer any FIVE.

Question 1

(a) Explain van der Waal's equation for a real gas. 4

(b) Briefly describe the considerations which led van der Waals' to his gas equation $(P+\frac{a}{V^{2}})(V-b)=RT$. Discuss how far this equation is in keeping with experimental facts. 12

(c) For carbon dioxide it is found that if unit pressure be taken as the standard barometric pressure and unit volume as the volume at N.T.P. then $a=0.00874$ and $b=0.0023$. Calculate $T_c$ for carbon dioxide gas. 4

Question 2

(a) Explain the thermal equilibrium. 2

(b) What is efficiency of an engine? Derive an expression for the efficiency of a Carnot engine in terms of the temperature of the source and the sink. 12

(c) A Carnot engine is operated between two reservoirs at temperatures of 450 K and 350 K. If the engine receives 1 kcal of heat from the source in each cycle, calculate (i) amount of heat rejected to the sink in each cycle, and (ii) efficiency of the engine. 6

Question 3

(a) What are coherent sources? Discuss why two independent sources of light of the same wavelength cannot produce interference fringes. 5

(b) Describe Young's double-slit experiment and drive an expression for (i) intensity at a point on the screen and (ii) fringe-width. 11

(c) In a double-slit experiment the separation between the slits is 2.5 mm and the distance of the screen from the slits is 50 cm. If the arrangement is illuminated with sodium light of wavelength 5890 $\mathring{\text{A}}$, calculate (i) the angular position of the first maxima, and (ii) the linear separation between two adjacent minima. 4

Question 4

(a) Define the lissajous figures. 2

(b) Derive a general expression for the resultant vibration of a particle simultaneously acted upon two initially perpendicular simple harmonic vibrations, having the same time but different amplitudes and phase angles. What happens if the phase difference is (i) 0, (ii) $\frac{\pi}{4}$ and (iii) $\pi$ radians? 12

(c) A particle executes simple harmonic motion given by the equation, $y=12\sin(\frac{2\pi t}{10}+\frac{\pi}{4})$ Calculate (i) amplitude, (ii) frequency, and (iii) displacement at $t=1.25$ sec. 6

Question 5

(a) Distinguish between the particle velocity and wave velocity. 4

(b) Derive the differential equation of one dimensional wave equation. 10

(c) The displacement (in metres) of a particle executing simple harmonic motion at any instant of time is given by, $y=0.1\sin 2\pi(340t-0.15)$ Calculate (i) wave velocity, (ii) wave length, and (iii) frequency. 6

Question 6

(a) Define electric flux. Give an expression for the flux in an electric field. 4

(b) State and prove Gauss's law of electrostatics. Using this theorem, derive an expression for the electric field at a point due to a plane sheet of charge. 12

(c) Portions of two large sheets of charge with uniform surface charge densities $\sigma_{+}=+6.8\,\mu\text{C/m}^{2}$ and $\sigma_{-}=-4.3\,\mu\text{C/m}^{2}$. Find the electric field $E$ of two sheets. 4

Question 7

(a) State and explain Ohm's law. 4

(b) Explain the terms 'current density' and 'drift velocity' of electrons inside a conductor. Show that the current density, $j=-nev_d$. 10

(c) A current of 3.0 A flows down a straight metal rod that has a 0.20 cm diameter. The rod is 1.5 m long and the potential difference between its ends is 40 V. Find (i) current density, (ii) field in the rod, and (iii) resistivity of the material of the rod. 6