Light-

LIGHT Light is a kind of energy, which travels in the form of electromagnetic waves and produces sensation in our eyes.

An object reflects light incident on it and this reflected light received by our eyes, makes us able to see the things around us. "In this way things are classified in two ways on the basis of reflection of light." (i) Luminous bodies: Those bodies which produce light, are called luminous bodies, e.g., electric bulb, sun, etc. (ii) Non-luminous bodies: Those bodies which cannot produce light, are called non-luminous bodies, e.g., book, chair, moon, etc. Non-luminous bodies when comes in contact of luminous bodies, becomes visible due to radiations incident on them. "On the basis of medium of propagation of light bodies are classified as follows:" (i) Opaque bodies: Those bodies which do not allow light to pass through them are called opaque bodies, e.g., wall, wood, book, etc. (ii) Transparent bodies: Those bodies which allow the light to pass through them are called transparent bodies e.g., glass, water, vacuum, air, etc. (iii) Translucent bodies: Those bodies, which allow to pass only part of light through them are called translucent bodies, e.g.. paper with oil spot on it, water, polythene, etc.

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Communication Skills-

INTRODUCTION Communication: Communication is the concept of sharing/exchanging of information/idea by writing, speaking or any other medium. It is a two-way process. Communication skills are often used in organization/business, home or at workspace by using soft skills. It is a way to represent yourself in front of other parties efficiently and effectively. For example, After completion of your educational qualification, when you apply for a job, you need to communicate for sending an email. Communication is performed from Birth to Death in everyone's life. TYPES OF COMMUNICATION Communication can be categorised in three ways: (1) Verbal Communication (2) Non-Verbal Communication (3) Visual Communication 1. Verbal Communication: It is a method to communicate by using speech or words. It is a basic type of medium which is used in family, friends and relatives. Verbal communication has the requirement to learn a specific language which is understood by both parties. It ...

Question-About Frustum

Question=A metallic right circular cone 20 cm high and whose vertical angle is 60° is cut into two parts at the middle of its height by a plane, parallel to its base. If the frustum so obtained, be drawn into a wire of diameter1/16 cm, find the length of the wire. Solution=Let VAB be the solid metallic right circular cone of height 20 cm. Suppose, this cone is cut by a plane parallel to its base at a point O' such that V O^ prime =0^ prime 0,i i.e. O' is the mid-point of VO. Let r1and r2 be the radii of circular ends of the frustum ABB'A'. In right triangles VOA and VO'A', we have tan 30 deg = (OA)/(VO) and tan 30 deg = O^ prime A^ prime VO^ prime 1(sqrt(3)) = r 1 20 : and 1/(sqrt(3)) = r_{2}/10 r_{1} = 20/(sqrt(3)) * cmi and r_{2} = 10/(sqrt(3)) cm Volume of the frustum = 1/3 * pi(r_{1} ^ 2 + r_{2} ^ 2 + r_{1}*r_{2}) * h Volume of the frustum = pi/3 * (400/3 + 100/3 + 200/3) * 10c * m ^ 3 = 7000/9 * pi*c * m ^ 3 Let the length of the wire of 1/16cm di...

Reflection of Light-

REFLECTION OF LIGHT The phenomenon of bouncing off the light in the same medium, when it falls on a polished or shiny surface, is called reflection of light. Example: A mirror, polished surface of metal, etc., reflects (or bounces off) most of the light falling or incident on it, as shown in figure 1.2. Where, i = Incident angle, PO = Incident ray, MN= Plane mirror, ON = Normal, r = Angle of reflection, 0Q= Reflected ray, o = Incident point. Laws of Reflection of Light (a) Angle of incidence (i) is always equal to angle of reflection (r). angle i = angle r, and (b) Incident ray, reflected ray and normal to the mirror at the point of incidence all the three lie in the same plane. These two laws of reflection of light are applicable for all kind of mirrors such as spherical mirror, plane mirror, curved mirror.

CNG and Nano Carbon

1. The natural gas (CNG)-run buses are harmful for humans as they emit 'nano carbon' particles which can cause cancer, according to a study conducted by council of scientific and industrial research (CSIR). 2.Through the study was conducted on a very limited sample size in Delhi,CSIR took the findings seriously owing to the health hazard,it poses to humans and alerted the central government for further follow up,CSIR's Director General Dr MO Garg said. 3. According to him,the study can change the perception that natural gas is a clean fuel as it does not emit any visible smoke,which is in contrast to smoke emitted by diesel-run vehicles and perceived as harmful for humans. 4. "Natural gas is supposed to be a clean fuel when used in internal combustion engines,right? But,I don't think people realise that what you see (smoke) is perhaps better than what you don't see (no smoke from CNG vehicles)," said Garg during his address at the Global Green Energy Conc...

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