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8 May, 2014 04:51 IST|Sakshi

EAMCET, PHYSICS

FLUID MECHANICS & SEMICONDUCTORS

1.    When an air bubble moves up from the bottom to top of a deep lake, then
1)    Its acceleration is constant
2)    Its acceleration decreases continuously
3)    Its velocity decreases and becomes constant
4)    Its velocity increases and becomes constant

2.    A ball rises to the surface at a constant velocity in a liquid, whose density is four times greater than the material of the ball. The ratio of force of friction acting on the ball to its weight is
1) 3 : 1 2) 1 : 3       3) 1 : 4        4) 4 : 1

3.    If the velocity head of a stream of water is 10 m, then speed of flow is
1) 16 cm/s    2) 14 m/s
3) 14 cm/s    4) 1 m/s

4.    Figure shows a spinning ball (clockwise) in uniform streamline flow of air. The ball experiences

1)    No resultant force
2)    An uplift 3)    Downward force
4)    Force in the direction of streamlines

5.    The pressures on the top and bottom surfaces of an aeroplane wings are 0.9 × 105 Pa and 105 Pa. The surface area of each wing is 50 m2. The dynamic lift on the plane is
1) 106 N    2) 5 × 104 N
3) 5 × 105 N    4) 105 N

6.    Water is flowing through horizontal pipe of variable cross-section. The velocity of flow is 1 m/s at a point when the area of cross-section is 1 cm2 and pressure is 2000 Pa. At a point when the area of cross-section is 5 cm2, the pressure will be
1) 2480 Pa    2) 480 Pa
3) 240 Pa    4) 280 Pa

7.    Water is taken in a cylindrical vessel of radius 20 cm which is rotating along its axis at the rate of 2 Hz. The liquid rises at the sides. The difference in the height of the liquid at the centre of the vessel and its sides is (p2 = g)
1) 0.82 m    2) 0.032 m
3) 0.08 m    4) 0.32 m

8.    The level of water in a tank is 5 m high. A hole of area 1 cm2 is made in the bottom of the tank. The initial rate of leakage of water from the hole is (g = 10 ms–2)
1) 10–1 m3 s–1         2) 10–2 m3 s–1
3) 10–3 m3 s–1         4) 10–3 m3 s–1

9.    In a horizontal pipe line of uniform cross-section, pressure difference between two points is 0.1 Pa. The change in the kinetic energy per Kg of water flowing in the pipe is
1) 10–5 J kg–1         2) 10–4 J kg–1
3) 10–3 J kg–1        4) 10–2 J kg–1

10.    Match the following
a) Poise    d) Kg m–1 s–1
b) Poiseullei    e) dy. s/cm2
c) Stoke    f) erg sec/g
1) a – e, b – f, c – d
2) a – e, b – d, c – f
3) a – f, b – e, c – d
4) a – d, b – e, c – f

11.    An air bubble of radius 0.5 mm rises in a liquid of coefficient of viscosity 0.1 SI units and density 900 kg m–3. The terminal velocity of the bubble is (g = 10 ms–2)
1) 5 mm/s    2) 5 cm/s
3) 5 m/s    4) 0.01 m/s

12.    A lead sphere of mass m falls through a viscous liquid with terminal velocity V0. Another lead sphere of mass 8 m falls through same liquid with a terminal velocity of
1) V0 2) 4 V0     3) 8 V0    4) 64 V0

13.    The difference in velocities between two layer of water 20
m apart in a flowing river is 4 ms–1. The shear stress between the layers is (h = 10–3 SI units)
1) 10–4 Pa    2) 5 × 10–5 Pa
3) 2 ×10–4 Pa    4) 4 × 10–4 Pa

14.    If the radius of the capillary tube is increased by 0.5%, the percentage increase in the rate of flow of liquid through it is
1) 1%  2) 4%       3) 0.5%    4) 2%

15.    The coefficients of viscosity of two liquids are in the ratio 2 : 3 and their densities are in the ratio 4 : 5. If these liquids are filled to same height indifferent vessels and are drained through identical capillary tubes then the volume of liquids collected per unit times will be
1) 8 : 15    2) 6 : 5
3) 15 : 8    4) 3 : 2

16.    A soft plastic bag of weight w0 is filled with air at STP. Now weight of the bag in air is w. Then
1) w > w0    2) w < w0
3) w = w0    4) w ³ w0

17.    For compressible fluids, equation of continuity is
1) r1v1 = r2v2     2) r1A1 = r2A2
3) r1A1v1 = r2A2v2
4) A1v1 = A2v2

18.    A pipe GB is fitted with two pipes C and D as shown. The pipes GB, BC and BD have areas of cross-sections A, A/2, A/3 respectively. At G, velocity of water is 10 m/s and at C, velocity is 6 m/s. If A = 24 m2 then velocity of water at D is (assume that flow is ideal)
1) 21 m/s    2) 3.3 m/s
3) 30 m/s    4) 16 m/s

19.    Water from a tap emerges vertically downward with an initial speed of 1 m/s. The cross-sectional area of the tap is 10–4 m2. Assume that pressure is constant through out the stream of water and that the flow is steady. The cross-sectional area of the stream 0.15 m below the tap is
1) 5 × 10–4 m2         2) 1 × 10–5 m2
3) 5.83 × 10–5 m2 4) 2 × 10–5 m2

20.    A diver is 10 m below the surface of water. The approximate pressure experience by the water is
1) 105 Pa    2) 2 × 105 Pa
3) 3 × 105 Pa    4) 4 × 105 Pa

21.    In a p-type semiconductor the acceptor level is situated 60 meV above the valence band. The maximum wavelength of light required to produce a hole will be
1) 0.207 × 10–5 m
2) 2.07 × 10–5  m
3) 20.7 × 10–5  m
4) 2075 × 10–5  m

22.    A p – n junction diode can with stand currents upto 10 mA under forward bias, the diode has a potential difference of 0.5 V across it which is assumed to be independent of current. The maximum voltage of the battery used to forward bias the diode when a resistance of 200 W is connected in series with it is
1) 3.5 V    2) 2.5 V
3) 6.5 V    4) 4.5 V

23.    A transistor connected in common emitter configuration has input resistance Rin = 2 K W   and load resistance of 5 K W. If    b = 60 and an input signal 12 mV is applied, the resistance gain, voltage gain and power gain respectively are
1) 2.5, 150, 9000
2) 4.5, 150, 9000
3) 2.5, 200, 9000
4) 2.5, 150, 9500

24.    At breakdown region of a Zener diode which of the following does not change much
1) Current     2) Voltage
3) Dynamic impedance
4) Capacitance

25.    A pulsating voltage is a mixture of an a.c. component and a d.c. component. The circuit used to separate a.c. and d.c. components is called
1) An oscillatory 2) An amplifier
3) A filter       4) A rectifier

26.    While using a transistor as an amplifier
1)    The collector junction is forward biased and emitter junction is reverse biased
2)    The collector junction is reverse biased and emitter junction is forward biased
3)    Both the junctions are forward biased
4)    Both the junctions are reverse biased

27.    A : In intrinsic semiconductor, conductivity is mainly due to the breakage of covalent bond.
B : In extrinsic semiconductor, the conductivity is mainly due to the addition of impurities.
1) Both A and B are true
2) Both A and B are false
3) A is true but B is false
4) A is false but B is true

28.    List - I    List - II
a) Emitter  b) Base     c) Collector
d) Transfer of resistance
e) Transistor
f) Moderately doped
g) Lightly doped
h) Heavily doped
The correct match is
1) a – f, b – e, c – h, d – g
2) a – g, b – f, c – e, d – h
3) a – h, b – g, c – f, d – e
4) a – e, b – h, c – g, d – f

29.    [A] : The potential difference across an unbiased p - n junction cannot be measured by connecting voltmeter across its terminals.
[R] : There are no free charge carriers in the depletion zone, voltmeter requires current to indicate potential difference.
1)    Both A and R are true and R is the correct explanation of A
2)    Both A and R are true but R is not the correct explanation of A
3)    A is true but R is false
4)    A is false but R is true

30.    In n - p - n transistor, in CE configuration
a)    The emitter is heavily doped than the collector
b)    Emitter and collector can be interchanged
c)    The base region is very thin but is heavily doped
d)    The conventional current flows from base to emitter
1) a and b are correct
2) a and c are correct
3) a and d are correct
4) b and d are correct

31.    Choose the only incorrect statement from the following
1)    In conductors, the valence and conduction bands may overlap
2)    Substances with an energy gap of the order of 10 eV are insulators
3)    The resistivity of a semiconductor increases with increase in temperature
4)    The conductivity of a semiconductor increases with increase in temperature

32.    The output from a full wave rectifier is
1) an ac voltage
2) a dc voltage     3) zero
4)    a pulsating unidirectional voltage

33.    For useful amplifying action, which of the following features should a transistor have ?
1)    The emitter should be heavily doped, the collector less heavily doped and the base lightly doped
2)    The area of the base-collector junction must be larger than that of the emitter-base junction
3)    The thickness of the base layer should be very small
4)    All the above features

KEY

1) 4    2) 1    3) 2    4) 2
5) 3    6) 1    7) 4    8) 3
9) 2    10) 2    11) 1    12) 2
13) 3    14) 4    15) 2    16) 3
17) 3    18) 1    19) 3    20) 2
21) 2    22) 2    23) 1    24) 2
25) 3    26) 2    27) 1    28) 3
29) 1    30) 3    31) 3    32) 4
33) 4

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