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 Ultra-violet radiation

Ultraviolet radiation is USED to kill microorganisms, molds and FUNGUS in various environmental applications. UV sterilization is used for air-purification systems, WATER purification, aquarium and pond maintenance, LABORATORY hygiene and food and beverage PROTECTION.

 Solid

Of the three phases of matter (gas, liquid, and solid), sound waves travel the SLOWEST through gases, faster through LIQUIDS, and fastest through solids.

 3 and 4 only

Working of safety FUSES depends UPON MAGNITUDE of the CURRENT and heating EFFECT of the current.

 None of these

Hydroscope is an optical device for enabling a person to see an object at a CONSIDERABLE distance below the SURFACE of water by MEANS of a series of mirrors enclosed in a steel tube. Hydrophone is an instrument used for recording sound under water. It is the underwater equivalent of a microphone that measures pressure fluctuations, and these are usually CONVERTED to sound pressure level (SPL), a logarithmic measure of the mean square acoustic pressure.

 Sonar

Sonar (originally an ACRONYM for Sound Navigation And Ranging) is a TECHNIQUE that uses sound propagation (usually UNDERWATER, as in submarine navigation) to navigate, communicate with or detect OBJECTS on or under the surface of the water, such as other VESSELS.

 Reaction

Newton’s third law STATES that “For EVERY action, there is an equal and opposite reaction.” The statement means that in every interaction, there is a pair of FORCES ACTING on the two interacting objects. The size of the forces on the FIRST object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. So harder the stone is kicked, the harder will be its effect on the hitter.

 Light waves

It is possible to TRANSFORM unpolarized light into polarized light. A light WAVE that is vibrating in more than one plane is REFERRED to as unpolarized light. Polarized light waves are light waves in which the vibrations OCCUR in a single plane. The PROCESS of transforming unpolarized light into polarized light is known as polarization.

 DRIVING a car to cover a DISTANCE

In driving a car to cover a distance, kinetic energy is being used in PERFORMING WORK.

 With the same SPEED

A solid SPHERE rolls down two different inclined planes of the same height but of different INCLINATIONS. The speed and the of DESCEND will be same.

 First law of thermodynamics

The 1st law of thermodynamics STATES that INTERNAL energy change of a system equals NET heat transfer minus net work DONE by the system.

 10 MEV

A photon’s RELATIVISTIC MOMENTUM is given by the equation,E = PC where p is the momentum.
P = 10 MeV/c
So, E = 10 MeV

 Work and TORQUE

The SI unit of work is the NEWTON-metre or joule (J). A Newton meter is ALSO the SI unit of torque (also CALLED “moment” or “moment of force”).

 The blood PRESSURE of a person INCREASES at high altitudes

Nosebleeds can be caused by being up in a very high ALTITUDE. As you CLIMB higher, the AMOUNT of oxygen in the air decreases. This makes the air thinner and dryer, which can in turn cause the inside of your nose to crack and bleed.

 Recording a PERMANENT three dimensional photograph of a given SINGLE COLOUR or a multicolour

Holography is a photographic TECHNIQUE that records the LIGHT scattered from an object, and then presents it in a way that appears three-dimensional.

 PRESSURE difference due to fast moving air in between

When a fast-moving TRAIN passes a MAN standing on the platform at rest, the air between train and person also moves with GREATER speed. This rapidly moving air, by Bernoulli's principle will have a lower pressure than the still air a few feet AWAY.

 Convex lens

A magnifying glass (CALLED a HAND lens in laboratory contexts) is a convex lens that is USED to produce a MAGNIFIED image of an object.

 Accidents due to expansion in SUMMER can be avoided

In a RAILWAY track, two RAILS are joined END to end with a gap in between them because accidents due to expansion in summer can be avoided.

 Disperson of light

The SPLITTING of DIFFERENT COLOURS of light in a PRISM is disperson of light.

 110^“10

The period of oscillation of 3 cm microwaves is 1 × 10^-10 (PHYSICS, VOLUME 1, by Halliday). The period of oscillation is the smallest interval of time in which a system undergoing oscillation RETURNS to the state it was in at the BEGINNING of the oscillation.

 NORMAL FAULTS

Tensional FORCES NORMALLY CAUSE normal faults.

 2 X AVERAGE VELOCITY - INITIAL velocity

 GEOTHERMAL energy

The ALTERNATIVE energy SOURCE which is exhaustible is geothermal energy.

 Forward

When a MAN jumps out of a moving train, his FEET suddenly comes to rest on TOUCHING the ground. But, the upper part of the body CONTINUES to be in motion and has a tendency to move forward. That is why the PERSON falls with his head forward.

 Virtual and erect

A CONCAVE lens always FORMS an IMAGE which is virtual and erect.

 Pressure

Manometers are precision INSTRUMENTS that are used to measure pressure, which is the force EXERTED by a gas or liquid per unit surface area OWING to the effects of the WEIGHT of that gas or liquid from gravity.

 Mud is a bad conductor

Clay is a poor conductor of heat as compared to wood and BRICKS. Therefore, clay neither allows the external heat to enter the HOUSE in SUMMER nor it allows the internal heat to escape out in WINTERS. Hence, mud houses remain colder in summer and WARMER in winter. mud or clay is poor conductor of electricity.

 PRESSURE

Energy PER UNIT volume is dimensionally equal to pressure.

 There will ALWAYS be water just beneath the ICE level

All liquids have a boiling point and a freezing point. Underneath the frozen upper LAYER, the water remains in its liquid form and does not freeze. Also, oxygen is trapped beneath the layer of ice. As a RESULT, fish and other aquatic animals find it possible to live COMFORTABLY in the frozen lakes and ponds.

 MICROPHONE

Conversion of SOUND ENERGY into ELECTRICAL energy is DONE by microphone.

 STORM

A slowly rising atmospheric pressure, over a week or TWO, typically indicates settled weather that will LAST a long time. A sudden drop in atmospheric pressure over a few hours often FORECASTS an approaching storm, with heavy rain and STRONG winds.

 PASCAL

Air PRESSURE is MEASURED in Pascal.

 Momentum

SINCE the FORCE and the duration of time for which it ACTED are same, the product of force and time will be the same for both. Since Force×time gives CHANGE in momentum of a body, and they had 0 momentum initially, their final momenta will be same.

 IMPULSE and MOMENT of FORCE

Impulse and moment of force.

 Ultraviolet radiations from Sun burn our retina

Exposing your EYES to the sun without PROPER eye protection during a solar eclipse can CAUSE “eclipse blindness” or retinal burns, also known as solar retinopathy. This EXPOSURE to the light can cause damage or even destroy cells in the retina (the back of the eye) that transmit what you SEE to the brain.

 Representing data in TERMS of measurable physical quantities.

Analog synthesis USES a mixture of COMPLEX sounds that are shaped by filtering. It is based on representing data in terms of measurable physical quantities, in this case SOUND WAVES.

 SILVER, COPPER, ALUMINIUM, Steel

Silver, Copper, Aluminium, Steel is ARRANGED in ORDER of decreasing conductivity.

 2 seconds

A seconds pendulum is a pendulum whose period is precisely two seconds; one SECOND for a swing in one DIRECTION and one second for the return swing, a frequency of 12 HZ.

 the FRICTION between SAND and FEET is LESS than that between CONCRETE and feet.

The friction between sand and feet is less than that between concrete and feet.

 VACUUM

Light TRAVELS at the FASTEST SPEED in Vacuum.

 Collision between fast neutrons and NITROGEN NUCLEI present in the ATMOSPHERE

Radiocarbon is PRODUCED in the atmosphere as a result of collision between fast neutrons and nitrogen nuclei present in the atmosphere.

 CENTRIFUGAL force

When MILK is churned vigorously the cream from it is SEPARATED out due to Centrifugal Force. Churning physically agitates the cream until it ruptures the FRAGILE membranes SURROUNDING the milk fat.

 ANEMOMETER

An anemometer is a device used for MEASURING wind speed and direction. It is ALSO a COMMON weather STATION instrument.

 Both the stones reach the ground at the same time

Both stones reach the ground at the same time. The initial SPEED is 0 for both stones, and the only acceleration working in that SYSTEM would be g (Gravity acceleration). So, as the distance is the same, the final speed will be the same time. The only reason which could change this result is a difference in the shape of the stones. While they fall to the ground, they must “open” a way across the air. The shape of the falling object will decide the force needed to open that way. This is CALLED the “Air resistance”. Depending on the shape of the object, the resistance force will be BIGGER or smaller. As this force works counter to g, the falling time will decrease. Between a feather and a PLUMB ball, the falling time will be the same in vacuum, but inside air, the resistance force for the feather has almost the same value than gravity, while for the ball, the resistance is very much weaker than gravity.

 FRICTION

A ball rolling ALONG the ground gradually slows down and finally comes to REST. It is the force of friction between the surface of the ball and the ground that BRINGS the MOVING ball to rest.

 HOOKE's LAW

A SPRING is an EXAMPLE of Hooke's law.

 Wavelength

The wavelength of sound changes with temperature. This is because the speed of sound changes with the temperature. Since the speed of sound is different at different temperature, this MEANS the wavelength of sound at a given frequency is a variable DEPENDING on the speed of sound. For example, the wavelength of a 100 CYCLE tone in air at 68ºF would be 11.27 feet while the same tone in fresh water at 68ºF would have a wavelength of 48.05 feet.

 300 m

If a CARRIER WAVE of 1000 kHz is used to carry the signal, the length of transmitting antenna will be equal to 300 m.

 Amplitude

The loudness of SOUND is directly PROPORTIONAL to the amplitude of the wave. The loudness of the sound increases with INCREASE in the amplitude vibration. The UNIT of loudness is decibel.

 EAST

With vertical, the RELATIVE velocity will be INCLINED and APPEAR to be coming from east.So the RAIN will appear to be coming from east.

 It is DEFINED as the RATIO of speed of LIGHT in vacuum to the speed of light in the MEDIUM.

The ratio of the velocity of light in a vacuum to its velocity in a specified medium.