Question Paper: Physics : Question Paper Jun 2015 - First Year Engineering (Semester 2) | Gujarat Technological University (GTU)
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## Physics - Jun 2015

### First Year Engineering (Semester 2)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

### Objective Question (MCQ)

1 (a) 1 The buoyant force of an object is depend on
(A)Object's density (
B)Mass of an object (
C)Area of an object (
D)Submerged area of an object.
(1 marks)
1 (a) 2 The unit of an inductance of an inductor is _______
(A)Henry (
C)coulomb (
D)Ohm.
(1 marks)
1 (a) 3 Which of the following is a Scalar quantity
(A)Momentum (
B) Force (
C) Mass (
D) Velocity.
(1 marks)
1 (a) 4 Ohm's Law is not applicable to
(A)Semiconductors (
B) DC Circuits (
C) High Currents (
D) Resistor.
(1 marks)
1 (a) 5 Potential difference is measured in
(A) Volts (
B) Amperes (
C) Joules (
D) Watts.
(1 marks)
1 (a) 6 An inductor stores energy in
(A)Electrostatic field (
B) electromagnetic field (
C) core (
D) magnetic field.
(1 marks)
1 (a) 7 Four identical resistors are first connected in parallel and then in series. The resultant resistance of the first combination to the second will be.
(A)$$\dfrac{1}{16}$$ times (B)$$dfrac{1}{4}$$times (
C) 4 times (
D) 16 times.
(1 marks)
1 (b) 1 The acceleration in a body is due to.
(A) Balanced force (
B) unbalanced force (
C) mass (
D) electrostatic force.
(1 marks)
1 (b) 2 If any block of material is float on liquid, what can say about block.
(A)Block is heavier than liquid (
B) liquid is heavier than block (
C) density of liquid is more than block (
D) density of block is more than liquid.
(1 marks)
1 (b) 3 Step up transformer decreases.
(A)Voltage (
B) current (
C) power (
D) frequency.
(1 marks)
1 (b) 4 Which is not a unit of Pressure?
(A)Bar (
B) Torr (
C) Pascal (
D) N/m.
(1 marks)
1 (b) 5 For an object which is on circular motion, it must have.
(A)Continuously accelerated (
B) Continuously slow down (
C) Continuously acted on balanced force (
D) none of these.
(1 marks)
1 (b) 6 What is the force acting on an object of mass 10 kg moving with a uniform velocity of 10m/s?
(A)100N (
B) 10N (
C) 0N (
D) 1N.
(1 marks)
1 (b) 7 What is the SI unit of surface tension.
(A)Nm (
B) Nm-1 (
C) Nm-2 (
D) Jm-1
(1 marks)

### Choose the correct answer from following options.

1 (c) 1 The SI unit of velocity is ______________
(a)Poise
(b)Pascal
(c)Joule
(d)none of these.
(1 marks)
1 (c) 2 The dimensional formula of surface tension is _____________
(a)M1L1T-1 (b) M1 L1 T-2
(c)M1L0T-2 (d) M1L-1T-1.
(1 marks)
1 (c) 3 Potential difference is measured in ___________
(a)Volt
(b)Ampere (c) Joule
(d)Watt.
(1 marks)
1 (c) 4 Kirchhoff's second law is based on law of conservation of _____________
(a)Charge
(b)Momentum
(c)Energy (d) Mass.
(1 marks)
1 (c) 5 In a colour code of resistor, number 3 is represented by ____________
(a) Blue
(b)Orange
(c)Grey
(d)Violet.
(1 marks)
1 (c) 6 Resistance of a conductor in the form of a wire depends on its ___________
(a)Pressure
(b)Length
(c)Temperature
(d)Material.
(1 marks)
1 (c) 7 An inductor stores energy in form of _____________
(a) Electrostatic field (b) Electromagnetic field
(c)Core
(d)Magnetic field.
(1 marks)

### Choose the correct answer from following options.

1 (d) 1 SI unit of torque is ___________
(a) Nm
(b)Nm-1
(c)Nm-2
(d)Jm-1.
(1 marks)
1 (d) 2 A cube of ice is floating in water contained in a vessel. When the ice melts, the level of water in the vessel____________
(a) rises
(b)falls
(c)remain unchanged
(d)falls at first and then rises to the same height as before
(1 marks)
1 (d) 3 The resultant of balanced force is ____________
(a) non zero (b) equal to zero
(c)not equal to zero
(d)equal to the acceleration produced in body.
(1 marks)
1 (d) 4 Inertia is ____________
(a) property of matter (b) type of force (c) speed of an object (d) none of these.
(1 marks)
1 (d) 5 The gravitational force of earth acting on a body of mass 1 kg is____________
(a) 8.9 N
(b)9.8 N
(c)980 N
(d)1 N.
(1 marks)
1 (d) 6 Which pair of variables defines motion?
(a) speed and distance (b) time and momentum
(c)Change of position and passage of time
(d)speed and passage of time.
(1 marks)
1 (d) 7 The acceleration in a body is due to ___________
(a) Balanced force (b) Unbalanced force (c) Mass (d) Electrostatic force.
(1 marks)
2 (a) Calculate the polarisability and relative permittivity in hydrogen gas with a density of 9.8×1026 atom/m3 . Given radius of the hydrogen atom to be 0.50Å.(3 marks) 2 (b) Deduce Clausis-Mossotti equation.(4 marks) 2 (c) (1) State any four factors affecting the acoustics of the building and give at least two remedies for each.
(2) Compare Hard and Soft Magnetic materials.
(7 marks)
3 (a) An ultrasonic source of 0.07 MHz sends down a pulse towards the seabed which returns after 0.65 sec. The velocity of sound in water is 1700 m/s. Calculate the depth of the sea and wavelength of pulse.(3 marks) 3 (b) Discuss the properties of superconductors.(4 marks) 3 (c) Explain the different types of fibers based on materials, mode and index profile.(7 marks) 4 (a) The reverberation time is found to be 1.5 sec for an empty hall and it is found to be 1.0 sec when a curtain cloth of 20 m2 is suspended at the centre of the hall. If the dimension of the hall are 10×8×6 m3 . Calculate the coefficient of absorption of curtain cloth.(3 marks) 4 (b) Define piezoelectric effect and draw the circuit diagram of piezoelectric oscillator and explain the production of ultrasonic waves using it.(4 marks) 4 (c) (1) Describe the construction and working of Nd: YAG Laser with a suitable energy level diagram.
(2) List out the properties and application of Metallic glasses.
(7 marks)
5 (a) A refractive index of core for step index fiber is 1.52, diameter is 2.9 ?m and a fractional difference of refractive index is 0.0007. It is operated at a wavelength of 1.3 ?m. Find the number of modes the fiber will support.(3 marks) 5 (b) Explain the producer of data recording and reading in magnetic tape.(4 marks) 5 (c) (1) Describe the Ball milling method to produce nano-particles.
(2) Compare Type-I and Type-II superconductors.
(7 marks)
6 (a) Discuss in detail the quantum confinement.(3 marks) 6 (b) With a neat sketch explain how a CNT is synthesized using chemical vapour deposition technique.(4 marks) 6 (c) What is the shape memory Alloys (SMA)? Explain the temperature induced and stress induced transformations in detail.(7 marks) 7 (a) What is solar cell? Discuss a few materials that are used in solar cell design.(3 marks) 7 (b) Explain briefly the carbon nanotubes (CNT) and their different structure.(4 marks) 7 (c) (1) A paramagnetic material has a magnetic field intensity of 104 A/m. If the susceptibility of the material at room temperature is 3.7×10-3 , calculate the magnetization and flux density of the material.
(2) Define the term (1) Dielectric constant (2) Magnetic susceptibility (3) Pumping (4) Total internal reflection
(7 marks)