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PHYSICS

Exam questions and solutions with
deep explanation
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Which among the following is the fundamental quantity ?
(1) Volume
(2) Time
(3) Velocity
(4) Force
Definition
The fundamental qualities of Physics are the seven basic quantities
that can be used to express all other physical quantities
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2
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Due to expansion, the size of the hole will also
increase so as to compensate for the distance change between the
molecules
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When a

substance is heated, its particles begin moving more and thus
usually maintain a greater average separation
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If the diameter of a capillary is doubled, then the rise of water in
it will be (1) two times
(2) half
(3) four times
(4) no change
Definition;

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So, if the radius of the tube is doubled, the
rise in the level of water will become half of the previous rise in the
capillary tube
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The effect can be seen in
the drawing up of liquids between the hairs of a paint-brush, in a
thin tube, in porous materials such as paper, in some non-porous
materials such as liquefied carbon fiber, or in a cell
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4
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So
the needle initially stays on the surface of the water and then sinks
into the water
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It is
revealed, for example, in the floating of some objects on the
surface of water, even though they are denser than water, and in
the ability of some insects (e
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water striders to run on the water
surface
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5
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How will it
come to an end ?
(1) Neutron Star
(2) Black hole
(3) White Dwarf
(4) Red Giant
Definition;
The mass of a star which is two times the mass of the sun turns
into a neutron star
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Such stars are
composed almost entirely of neutrons, which are subatomic
particles without electric charge and with slightly larger mass than
protons
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This principle states that no two
neutrons (or any other fermionic particles) can occupy the same
place and quantum state simultaneously
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4 and 3
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6
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Which among the following
statements is true regarding it?
(1) they fall with that ultimate velocity, which is different for
different droplets
(2) they fall with the same ultimate velocity
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Gravity
accelerates all objects towards the ground at a specific rate
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In general the air
resistance on an object depends upon several variables
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Its shape determines the
object’s drag coefficient: the more aerodynamic the shape, the less
drag
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And lastly, it depends upon the speed of the
object
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Most objects falling through
the air would be considered to be moving at a higher speed, even
though that speed might not be great compared to some velocities
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For which Diode is used ?
(1) modulation
(2) oscillation
(3) amplification
(4) purification
Definition;
The most common function of a diode is to allow an electric
current to pass in one direction (called the diode’s forward
direction), while blocking current in the opposite direction (the
reverse direction)
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8
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Homi J
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Vikram Sarabhai
(3) Dr
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P
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Iyengar
Definitions;
Homi Jehangir Bhabha was an Indian nuclear physicist, founding
director, and professor of physics at the Tata Institute of
Fundamental Research
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His major contribution included his work on Compton
scattering, R-process, and furthermore the advancement of nuclear
physics
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9
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Anthracite (“coallike”) is a hard, compact variety of mineral coal
that has a high luster
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Anthracite is the
most metamorphosed type of coal (but still represents low-grade

metamorphism), in which the carbon content is between 92
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10
...
M
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They are also used for mobile
applications such as communications to ships, vehicles, planes
and handheld terminals, and for TV and radio broadcasting
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e
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Microwaves are
especially suitable for this use since they are more easily focused
into narrow beams than radio waves, and also their comparatively
higher frequencies allow broad bandwidth and high data flow
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What is found in frequency modulation ?
(1) Fixed frequency
(2) Fixed dimension
(3) Change in frequency and dimension
(4) Change in dimension only
Definition;
Frequency modulation (FM) conveys information over a carrier
wave by varying its instantaneous frequency
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Frequency modulation
is also used in telemetry, radar, seismic prospecting and newborn
EEG seizure monitoring
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FM signal
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12
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Suppose a car whose mass is ‘x’ and is braked
from a speed of y km/hr to come to halt at a uniform retardation in z
min
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e
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Note that all the parameters remain the same
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The dimension of which of the following is the same as that of
impulse ?
(1) Volume
(2) Momentum
(3) Torque
(4) Change in the rate of momentum
Definition;
The quantity of impulse is force × time interval
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For example, a heavy
truck moving fast has a large momentum—it takes a large and
prolonged force to get the truck up to this speed, and it takes a

large and prolonged force to bring it to a stop afterwards
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14
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Which among the following
statements is true regarding it?
(1) they fall with that ultimate velocity, which are different for
different droplets
(2) they fall with same ultimate
(3) their velocity increases and they fall with different velocity on
the earth
(4) their velocity increases and they fall with the same velocity on
the earth
DEfinition;
Any mass is attracted to the Earth by the pull of gravity
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Without any other forces present, the speed of an object in free fall
will increase the farther or longer it falls
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First, it
depends upon the shape of the object
...
Second, it depends upon the size of the object; specifically
the cross-sectional area presented to the airflow (perpendicular to
the direction of travel)
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At low speeds the object’s resistance is directly
proportional to speed, and at higher speeds the object’s resistance
is proportional to its speed squared
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15
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A
photocopier (also known as a copier or copy machine) is a machine
that makes paper copies of documents and other visual images
quickly and cheaply
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Copiers can also use
other technologies such as ink jet, but xerography is standard for
office copying

16
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6 Megajoule
(2) 3
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2 Megajoule
(4) 4
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6
megajoule
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However, this must be understood
as an overly simplified definition, as the laws of thermodynamics
demonstrate that not all energy can perform work
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What is the minimum escape velocity of a rocket to be launched
into space ?
(1) 5 Km/Sec
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(3) 11 Km/Sec
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Definition;

On the surface of the Earth, the escape velocity is about 11
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96 mi/s), which is approximately 34 times
the speed of sound (Mach 34) and several times the muzzle velocity
of a rifle bullet (up to 1
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However, at 9,000 km altitude in
“space”, it is slightly less than 7
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In physics, escape velocity
is the speed at which the kinetic energy plus the gravitational
potential energy of an object is zero
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A
rocket moving out of gravity well does not actually need to attain
escape velocity to do so, but could achieve the same result at any
speed with a suitable mode of propulsion and sufficient fuel
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18
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When the
sun shines from behind us into the rain, incident rays of light enter
the drop and are refracted inwards
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A rainbow is an optical and
meteorological phenomenon that is caused by reflection of light in
water droplets in the Earth’s atmosphere, resulting in a spectrum of
light appearing in the sky
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How much calorie of energy is released by a boiled egg ?
(1) 40
(2) 50
(3) 60
(4) 77

Definition;

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Boiled
eggs are eggs (typically chicken eggs) cooked by immersion in
boiling water with their shells unbroken
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The snow on the mountains does NOT melt all at once when it
is heated by the sun because:
(1) it becomes very hard
(2) it reflects most of the heat from the sun
(3) it has a low specific heat capacity (4) it has a high latent heat of
fusion
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This means that the sun is powerless to melt clean
snow
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Snow does not melt on a spring day because of the sun’s heat
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21
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The whistle heard is
(1) the same in both cases in all respects
(2) of higher intensity when train arrives
(3) of higher pitch when train arrives
(4) of higher pitch when the train departs
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(Sound can
propagate through solids as well, but there are additional modes of
propagation
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In air at standard temperature and
pressure, the corresponding wavelengths of sound waves range
from 17 m to 17 mm
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Now if we consider these
cases, then the train which is arriving towards us has whistles of

higher pitch because it propagates through a medium which is
coming towards us but the train which is leaving propagates
through a medium moving further away from the listener and thus
producing a whistle of lower pitch
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Holography is a technique of
(1) recording a permanent, sharp two dimensional black and white
or multi color photograph
(2) recording a permanent three dimensional multi color
photograph
(3) recording a permanent three dimensional black and white
photograph
(4) recording a permanent three dimensional photograph of a given
single color or a multicolour
Definition;
Holography is a technique which enables three dimensional
images to be made
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The image changes as the position and orientation of
the viewing system changes in exactly the same way as if the
object were still present, thus making the image appear
three-dimensional
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Holography is a technique that enables
a light field, which is generally the product of a light source
scattered off objects, to be recorded and later reconstructed when
the original light field is no longer present, due to the absence of
the original objects
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The velocity of sound in moist air is more than in dry air
because the moist air has
(1) less density than dry air
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(3) more pressure than dry air
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Definition;
The density of dry air is more than that of moist air (when moisture
is removed from air, its density increases)
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Therefore, the speed of sound in moist air is more than that in dry
air
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An ice block with a piece of lead embedded in it floats in water
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When the ice melts, the lead piece sinks in
water since r1 is greater than the density of water
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So, the total volume of the water
produced by ice and that displaced by the lead piece is V w1 =
(V–v) r1 + v r1 < V w
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25
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Definition;
Electrons are generally responsible for heat conduction
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It depends on the specific
conductor you’re using
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26
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The physical and
mechanical properties of these materials vary with regard to
strength, rigidity, dimensional stability, lubrication requirements,
moisture absorption, etc
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Two or more gears working in tandem are called a
transmission and can produce a mechanical advantage through a
gear ratio and thus may be considered a simple machine
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27
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Ozone is formed
from di-oxygen by the action of ultraviolet light and also
atmospheric electrical discharges, and is present in low
concentrations throughout the Earth’s atmosphere
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6 parts per million of the atmosphere
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This
same high oxidizing potential, however, causes ozone to damage
mucus and respiratory tissues in animals, and also tissues in
plants, above concentrations of about 100 parts per billion
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28
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Definition

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One curie (1 Ci) is equal to 3
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Radioactivity
refers to the particles which are emitted from nuclei as a result of
nuclear instability
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The most common types of
radiation are called alpha, beta, and gamma radiation, but there are
several other varieties of radioactive decay
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Which of the following is used in the oven ?
(1) X-rays
(2) UV rays
(3) Microwaves
(4) Radio Waves
Definition;

An oven that uses micro radiation waves as a source of heat in
order to cook food as opposed to a fire source
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Perry Spencer allegedly discovered the heating properties
of microwaves while studying the magnetron
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Microwave ovens heat
foods quickly and efficiently because excitation is fairly uniform in
the outer 25–38 mm of a dense (high water content) food item; food
is more evenly heated throughout (except in thick, dense objects)
than generally occurs in other cooking techniques
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45 gigahertz (GHz)—a wavelength of 122
millimeters (4
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Microwave radiation is
between common radio and infrared frequencies
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When heated from 00 to 10C volume of a given mass of water will :
(1) Increase gradually
(2) Decrease gradually
(3) Increase and then will decrease
(4) Decrease and then will increase
Definitions;
When heated from 00 to 100 C volume of a given mass of water will
first decrease and then increase
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Water vapor can
be produced from the evaporation or boiling of liquid
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So the
volume first decreases and then increases again when water
droplets form from the vapors due to stoppage of heat
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The splitting of different colors of light in a prism is :
(1) Reflection of light
(2) Dispersion of light
(3) Diffraction of light
(4) Refraction of light

Definition;
The refractive index of many materials (such as glass) varies with
the wavelength or color of the light used, a phenomenon known as
dispersion
...
In optics, dispersion is the phenomenon
in which the phase velocity of a wave depends on its frequency, or
alternatively when the group velocity depends on the frequency
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Dispersion is sometimes called chromatic dispersion to emphasize
its wavelength dependent nature, or group-velocity dispersion
(GVD) to emphasize the role of the group

32
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Floating of the boat works on the principle of
buoyancy force which is an upward force exerted by a liquid, gas or
other fluid, that opposes the weight of an immersed object
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Thus a column of fluid, or an object
submerged in the fluid, experiences greater pressure at the bottom
of the column than at the top
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33
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Definition;
Surface tension is a contractive tendency of the surface of a liquid
that allows it to resist an external force
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It is revealed, for example, in the floating of
some objects on the surface of water, even though they are denser
than water, and in the ability of some insects (e
...
water striders) to
run on the water surface
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A circular plate, a cube and a sphere, all made up of the same
material and having the same mass, are heated to 300°C and left in
a room
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Experiments showed that the cooling rate is
approximately proportional to the difference of temperatures
between the heated body and the environment
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Surface area or volume ratio is an
important influence on temperature control
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So the sphere cools slowest and plate
cools fastest
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Optic fibers are used in :
(1) CAT scans
(2) X-ray photos
(3) Ultrasound scans
(4) Endoscopy
Definition;
(4) Optical fibers are used in endoscopic instruments that enable
doctors to view internal body parts without having to perform
surgery
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Further innovations included using
additional fibers to channel light to the objective end from a
powerful external source, thereby achieving the high level of full
spectrum illumination that was needed for detailed viewing, and
color photography
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Alongside the advances to the
optical side, the ability to ‘steer’ the tip was developed, as well as
innovations in remotely operated surgical instruments contained
within the body of the endoscope itself
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36
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5 mm and frequency 10 Hz,
are traveling in opposite directions with a speed of 20 mm/s
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0
(2) 1
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5
(4) 2
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The distance between the
adjacent nodes will be a 2 , Speed of the wave, i
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, V = nl
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So, l = 2 mm

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