Joint Entrance Screening Test (JEST) Past Year Question Papers 2020 Part 1

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PART a: 1 Mark Questions

Q1. The persons named A, B, C, D, E, F, G, H, I, J have come for an interview. They are being called one by one to the interview panel at random. What is the probability that C gives interview before A and A gives before F?

(a)

(b)

(c)

(d)

Q2. The ratio of maximum to minimum resistance that can be obtained with N number of resistors is (a) N

Q3. Consider three infinitely long, straight, and coplanar wires, which are placed parallel to each other. The distance between the adjacent wires is d. Each wire carries a current I in the same direction. Consider points on either side of the middle wire where the magnetic field vanishes. What is the distance of these points from the middle wire?

Q4. A rod consists of two equal sections of length l each with coefficient of thermal

, respectively. One end of the rod is kept at a fixed temperature and the other end at a temperature . If then the temperature at the interface is

(a)

(b)

(c)

(d)

Q5. If f (t) is a real and even function of t, which one of the following statements is true about its Fourier transform (here ⚹ indicates complex conjugation) ?

(a)

(b)

(c)

(d)

Q6. Consider an ideal gas whose entropy is given by

,

where n is the number of moles, is a constant, R is the universal gas constant, U is the internal energy and V is the volume of the gas. The specific heat at constant pressure is then given by

(a)

(b)

(c)

(d)

Q7. A 16 - bit analog to digital converter works in the range 0 - 1 Volt. The least count of the converter is

(a)

(b)

(c)

(d)

Q8. A particle in a spherically symmetric potential is known to be in an Eigen state of and with eigenvalues and , respectively. What is the value of ?

(a)

(b)

(c)

(d)

Q9. A particle of mass m carrying angular momentum l moves in a central potential

, where k, a are positive constants. If the particle undergoes circular motion, what is the equation determining its radius ?

(a)

(b)

(c)

(d)

Q10. Calculate the collector current and determine whether or not the transistor in figure shown below is in saturation. Assume

(a) 6.5mA, not in saturation

(b) 11.5mA, in saturation

(c) 11.5mA, not in saturation

(d) 6.5mA, in saturation

Q11. Charges are placed as follows: q at and and -q at and . At large distances, how does the electrostatic potential behave as a function of the distance r from the centre ?

(a)

(b)

Q12. An Hermitian matrix A is not a multiple of the identity matrix. Which one of the following statements is always true?

(a)

(b)

(c)

(d)

Q13. A ring of radius 0.5m has a gap of . If the ring carries a charge of + 1.0C distributed uniformly along it, then the electric field at the centre of the ring is