Showing posts from April, 2020

Sample questions paper class11 cbse physics

CBSE SAMPLE QUESTIONS PAPER- CLASS 11 Grade       : XI                                       Subject: PHYSICS                               Marks: 70       Time        : 3hrs                                    General Instructions : a)  All the questions are compulsory. b)  There are 37 questions. c)  This question paper contains four sections: Section-A, Section-B, Section-C and Section-D d)  Section-A contains 20 one mark questions.(MCQs, fill in the blanks and definitions) e)  Section-B contains 7 two mark questions with choice questions. f)  Section-C contains 7 three mark questions with choice questions. g) Section –D contains 3 five mark questions with internal choice.                  SECTION – A 1.       Special theory of relativity explained by a)       Thomas Alva Edison                                              b) Ampere c)    Albert Einstein                                                      d) C V Raman 2.          Among the giv

Kepler laws

KEPLER'S LAWS OF PLANETARY MOTION Kepler I law:                  Every planet revolves around the sun in an elliptical orbit with the sun is at one of its foci. This law is also known as the law of Orbits. Kepler II law:            The radius vector drawn from the sun to the planet gives equal areas in equal interval of time. That means the rate of change of the area of the planet / areal velocity is constant. This law is also known as the law of areas. Kepler III law:            The time period (T) of the planet revolving around the sun is directly proportional to the cube of the semi-major axis (a) of the orbit. This law is also known as the law of periods.                              i.e    T 2 α a 3                    

Questions on Electric charges and fields

  EVOLUTION QUESTIONS AND ANSWERS Question:  In damped weather, automobile ignition failure happens. Give the reason? Answer:  Generally, the spark plug's surface accumulates a film of dirt. The surface dirt hygroscopic hence attracts moisture from the air. Therefore, in humid weather, plugs become quasi-conductor.  So ignition failure happens. Question: Why a charged body can attract a piece of paper? Answer: A piece of paper is a dielectric. When a positively charged body is brought near to piece of paper, atoms of paper get polarized (In the neutral body, charge separation as + and -) with the center of opposite charge of atoms coming closer to the charged body. So the charged body can attract a piece of paper. Question: A charged body can attract another uncharged body? Explain why? Answer: Yes, because when a charged body is brought very near to an uncharged body, an opposite induced charge will develop across the uncharged body. The therefore charged

Gravitation class 11 important questions

GRAVITATION Important questions    Topics to be focused in this lesson Newtons law of gravitation Kepler's laws Acceleration due to gravity Orbital velocity and Escape velocity Gravitational potential and potential energy Kinetic and Total gravitational energy Derive an expression for the variation of acceleration due to gravity above and below the surface of the Earth. Explain Kepler’s law with necessary diagrams. What is orbital velocity? Show that orbital velocity is independent of mass of the body. What is escape velocity? Obtain an expression for it and what is the value of escape velocity of the Earth. Hydrogen is in abundance around the sun but not around earth. Explain The magnitude of the force of gravity between two identical objects is given by F. If the mass of each object is doubled but the distance between them is halved, then find the new force of gravity between the objects. The ratio of mean distances of three planets from th

Electric charges and fields class 12 questions with answers

ELECTRIC CHARGES AND FIELDS Focus to be on the topics Electric charges and its properties The intensity of Electric field Electric dipole Gauss law and its applications 1 MARK QUESTIONS Write any two properties of electric charges. State Coulomb's law of force between charges at rest. Define the dielectric constant. Give the SI unit of electric permittivity of free space. Define linear charge density and give its SI units. Define the electric field at a point in an electric field. What is an electric dipole? When is the torque on a dipole in an electric field maximum? Define electric flux. Is electric dipole moment a scalar or vector? Define Gauss law. What is the intensity of the electric field at a point inside the charged spherical shell? Write SI units for the intensity of the electric field. What is the effect of medium on the force between two point charges at a fixed distance? What is the least possible value of charge?             Answe