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A Carnot’s engine working between 400 K and 800 K has a work output of 1200 J per cycle. The amount of heat energy supplied to the engine from the source in each cycle is :

a. 1800 J b. 3200 J c. 2400 J d. 1600 J Answer: (c) η =1–(T2/T1) T1 = source’s temperature T2 = sink’s temperature η =... View Article

A car accelerates from rest at a constant rate for some time after which it decelerates at a constant rate to come to rest. If the total time elapsed is t seconds, the total distance travelled is :

a. b. c. d. Answer: (a) Let t be total time travelled v'→velocity after time t1 then, t1 + t2 = t, V' = 0 +αt1 (for... View Article

An electron of mass m and a photon have the same energy E. The ratio of the wavelength of an electron to that of the photon is : (c being the velocity of light)

a. b. c. d. Answer: (c) For photon, For electron,... View Article

For what value of displacement do the kinetic energy and potential energy of a simple harmonic oscillation become equal?

a. x = A/2 b. x = 0 c. x = ±A d. x = ± A/√2 Answer: (d) KE = PE (½)k(A2–X2)= 1/2kX2 Here, k = spring... View Article

The vernier scale used for measurement has a positive zero error of 0.2 mm. If while taking a measurement it was noted that ‘o’ on the vernier scale lies between 8.5 cm and 8.6 cm, vernier coincidence is 6, then the correct value of the measurement is ……………………. cm. (least count = 0.01 cm)

a. 8.36 cm b. 8.56 c. 8.58 cm d. 8.54 cm Answer: (d) Reading = MSR + VSD × LC – zero error Vernier scale Reading = 6 ×... View Article

A body of mass 2 kg moves under a force of [latex](2hat{i}+3hat{j}+5hat{k})N[/latex]. It starts from rest and was at the origin initially. After 4s, its new coordinates are (8, b, 20). The value of b is _______. (Round off to the Nearest Integer)

Answer: (12) time = 4 sec As the body starts from rest therefore position vector initially; and u (initial velocity) = 0 Given, Now, from... View Article

A solid disc of radius ‘a’ and mass ‘m’ rolls down without slipping

A solid disc of radius 'a' and mass 'm' rolls down without slipping on an inclined plane making an angle θ with the horizontal. The... View Article

A swimmer can swim

A swimmer can swim with a velocity of 12 km/h in still water. Water flowing in a river has a velocity of 6 km/h. The direction with respect to... View Article

The energy dissipated by a resistor is 10 ml in 1 s when an electric current of 2mA flows through it. The resistance is ________. (Round off to the Nearest Integer)

Answer: (2500) H = i2Rt 10 × 10-3 = 4 × 10-6 R ∴ 10 × 103 / 4 = R ∴ R = 2500 Ω... View Article

A force vecf equal 4hati plus 3hatj plus 4hatk is applied on an intersection point of x equal 2 plane and x axis the magnitude of torque of this force about a point 2 3 4 is

Answer: (20) Given: , , , , , , ,... View Article

For an ideal heat engine, the temperature of the source is 127ºC. In order to have 60% efficiency the temperature of the sink should be ________ºC. (Round off to the Nearest Integer)

Answer: (113) η = (1 - T2 / T1) = 0.6 = 1 - T2 / 400 T2 / 400 = 0.4 T2 = 160 K T2 = 160 – 273 T2 = -113°C... View Article

parallel plate capacitor

In a parallel plate capacitor set up, the plate area of the capacitor is 2 m2 and the plates are separated by 1 m. If the space between the... View Article

If one wants to remove all the mass of the earth to infinity in order to break it up completely. The amount of energy that needs to be supplied will be x/5 GM² / R where x is __________. (Round off to the Nearest Integer). (M is the mass of earth, R is the radius of earth, G is the gravitational constant)

Answer: (3) Energy given = Uf – Ui E = Uf – Ui E = So, x = 3... View Article

A deviation of 20 degrees is produced in the yellow ray

Answer: (12) θnet = 0 θ1 - θ2 = 0 θ1 = θ2 ω1 δ1 = ω2 δ2 and δnet = δ1 - δ2 = 2o δ1 = ω1 δ1 / ω2 = 2o δ1 = (1 - ω1 / ω2 ) = 2o δ1 = (1 -... View Article

A closed organ pipe of length L and an open organ pipe

A closed organ pipe of length L and an open organ pipe contains gases of densities ρ1 and ρ2 respectively. The compressibility of gases... View Article

Find out the surface charge density at the intersection of point x = 3 m plane and x-axis in the region of uniform line charge of 8 nC/m lying along the z-axis in free space.

a. 47.88 C/m b. 0.07 nC m-2 c. 0.424 nC m-2 d. 4.0 nC m-2 Answer: (c) Electric field due to wire is given by E = Electric field with... View Article

In order to determine the Young’s Modulus of a wire

In order to determine the Young's Modulus of a wire of radius 0.2 cm (measured using a scale of least count = 0.001 cm) and length 1m (measured... View Article

The half-life of Au¹⁹⁸ is 2.7 days. The activity of 1.50 mg of Au¹⁹⁸ if its atomic weight is 198 g mol-1 is (N_A = 6 × 10²³/mol).

a. 252 Ci b. 357 Ci c. 240 Ci d. 535 Ci Answer: (b) Initial activity = Ao = λNo = 366 Ci ∴ Approximately the correct... View Article

The magnetic field in a region

The magnetic field in a region is given by . The emf induced in the loop is: a. b. c. d. Answer: (b) ∈net... View Article

Two identical antennas mounted on identical towers are separated from each other by a distance of 45 km. What should nearly be the minimum height of the receiving antenna to receive the signals in line of sight? (Assume radius of earth is 6400 km)

a. 19.77 m b. 79.1 m c. 158.2 m d. 39.55 m Answer: (d) D = 2√2Rh... View Article