Thursday, 15 January 2015


If  force is expressed in Newton and the distance in metre, then the work done is expressed in ?
Joule ( The joule, symbol J, is a derived unit of energy, work, or amount of heat in the International System of Units. It is equal to the energy transferred (or work done) when applying a force of one newton through a distance of one metre (1 newton metre or N·m), or in passing an electric current of one ampere through a resistance of one ohm for one second.)

Free surface of a liquid behaves like a sheet and tends to contract to the smallest possible area due to the 
Force of cohesion (Cohesion or cohesive attraction or cohesive force is the action or property of molecules sticking together, being mutually attractive. It is an intrinsic property of a substance that is caused by the shape and structure of its molecules.Water, for example, is strongly cohesive as each molecule may make four hydrogen bonds to other water molecules in a tetrahedral configuration.
Cohesion, along with adhesion (attraction between unlike molecules), helps explain phenomena such as meniscus, surface tension and capillary action.
Mercury in a glass flask is a good example of the effects of the ratio between cohesive and adhesive forces. Because of its high cohesion and low adhesion to the glass, mercury does not spread out to cover the top of the flask, and if enough is placed in the flask to cover the bottom, it exhibits a strongly convex meniscus, whereas the meniscus of water is concave. Mercury will not wet the glass, unlike water and many other liquids,and if the glass is tipped, it will 'roll' around inside.)

Fathometer is used to measure?
Ocean depth (A depth finder that uses sound waves to determine the depth of water.)

For seeing objects at the surface of water from a submarine under water, the instrument used is ?

Fuse wire made of metal having?
Low melting point Fuse wire is normally tinned copper wire (tinned meaning that it has had a coat of solder).Low melting point metals such as lead or tin are used in fuses. )

The hottest part of the gas flame is known as ?
Non-luminous zone

The heat required to raise the temperature of body by 1k is called?
Thermal capacity 

Ultrasonic wave are those sound waves having frequency ?
More than 20 kilohertz (The hertz (symbol Hz) is the unit of frequency in the International System of Units (SI) and is defined as one cycle per second.)

Which waves are called waves of heat energy?
Infrared waves (Infrared radiation is popularly known as "heat radiation", but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49% of the heating of Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths.
Infrared (IR) is invisible radiant energy, electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 700 nanometers. Most of the thermal radiation emitted by objects near room temperature is infrared.
Earth's surface and the clouds absorb visible and invisible radiation from the sun and re-emit much of the energy as infrared back to atmosphere.
Infrared is used in night vision equipment when there is insufficient visible light to see.)

Kilowatt-hour is the unit of ?
Electric energy

which mirror is used to make periscope ?
Plane mirror

A light year is a unit of ?
Distance 9.4607×1015 m)

The Celsius temperature is a ?
Absolute temperature 

Light-eliminating diode (LED) converts?
Electrical energy into light energy 

In terms of magnetic properties oxygen belong to ?
Paramagnetic materials(Paramagnetism is a form of magnetism whereby certain materials are attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. Paramagnetic materials include most chemical elements and some compounds; they have a relative magnetic permeability greater than or equal to 1 (i.e., a positive magnetic susceptibility) and hence are attracted to magnetic fields. Exmaples - Hydrogen, Hellium, Berylium, Boron, Carbon, Nitrogen, Neon, Silicon, Phosphorus, Sulfur, chlorine Argon.
Diamagnetic materials are repelled by magnetic fields and form induced magnetic fields in the direction opposite to that of the applied magnetic field. Examples - Lithium, Oxygen, Sodium, Magnesium, Aluminium, Calcium. 
Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets.The common ones are iron, nickel, cobalt and most of their alloys)

1 light year is equivalent to?
9.46 * 1012km

The inertia of an object tends to cause the object?
To resist any change in its state of motion

Force is equal to ?
Mass * Acceleration

What is the formula for Impulse?
Impulse = Force * Time

Action and reaction are equal and opposite and they act on ?
Different bodies 

The area under velocity -time graph is ?

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