Showing posts with label Physics. Show all posts
Showing posts with label Physics. Show all posts

Jul 28, 2012

Lens Formula and Important Terms with Definitions in Physics

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Rotational Motion

Rotational Inertia: That property of an object to resist any change in its state of rotation. If at rest the body tends to remain at rest; if rotating, it tends to remain rotating and will continue to do so unless acted upon by a net external torque.

Jul 25, 2012

Stress and Strain Curve

Stress strain (curve):

The diagram shows the stress-strain curve for a ductile material. From the first part OA it is clear that Stress ∝ Strain. So, up to the point A, known as proportionality limit, Hooke’s law is obeyed. On further increase in stress, strain also increases but they are not increased proportionally. If the wire is unloaded up to the point B, it regains it’s original shape and size, so the point B is known as elastic limit or yelled point.

Heat and Thermodynamics

What is heat?
Heat is a form of energy which gives us sensation of warmth. In other words, we can define heat as the total sum of kinetic energy produced due to the vibration of molecules of the element. Its unit is Joule (J) in SI system and calorie in CGS system.

What is temperature?
The degree of hotness or coldness of body is called temperature. It is also defined as the property by virtue of which identify whether the body in thermal equilibrium or not. When two bodies are in thermal contact they posses a common property which is represented by a numerical value is called temperature. Temperature is measured by thermometer. Its unit is Kelvin.

Jul 24, 2012

Hooke's Law and Its Experimental Verification

Robert Hooke performed an experiment on coiled spring, metallic rod or metallic wires etc and gave a law known as Hooke's law. It states that, "The restoring force developed on a body is directly proportional to the elongation produced on it, within the elastic limit."
      i.e. F∝x
      ∴F=-Kx       [Where K is proportionality constant.]

Young modified Hooke's statement and stated as, "Within elastic limit, the stress developed on the body is directly proportional to the strain produced on it."

Jul 23, 2012

Millikan's Oil Drop Experiment

When a spherical charged body of radius r falls under the effect of various forces in a viscous medium of viscocity η, it attends the terminal velocity vt when the viscous force becomes 6πηrvt (Stoke’s law)

Experimental setup and Theory: An experimental setup of Millikan’s experiment to determine the change in oil drop is shown in figure. At first, clock oil (non volatile) is allowed to fall drop wise from the opening of upper plate A with the help of atomizer. This law undergoes collision with air particles and gets charged. The whole apparatus is kept inside double walled chamber inside which water is circulated for cooling purpose. The chamber consists of 2 windows.

Jul 22, 2012


An atom is electrically neutral. Why?
Electrons moves round a positively charged nucleus. Nucleus contains as many positively charged protons as there are electrons. The charge carried by an electron and proton are equal in magnitude and opposite in sign. Hence atom as a whole is neutral.

Explain why the induced charges are not always equal to inducing charge in magnitude?
The charge induced on an insulator is always less than inducing charge in magnitude as the insulator has bound charges while charge induced on conductor equals to the inducing charge in magnitude.

Jul 17, 2012

Huygen's Principle

Huygen’s Principle is a geometrical construction which was designed to determine the position, shape and the size of a wavefront in future if its present position and nature is known.
In 1678, Huygens proposed that every point to which a luminous disturbance reaches becomes a source of a spherical wave; the sum of these secondary waves determines the form of the wave at any subsequent time. He assumed that the secondary waves travelled only in the "forward" direction and it is not explained in the theory why this is the case. He was able to provide a qualitative explanation of linear and spherical wave propagation, and to derive the laws of reflection and refraction using this principle, but could not explain the deviations from rectilinear propagation which occur when light encounters edges, apertures and screens, commonly known as diffraction effects.  Wikipedia

Jul 13, 2012

Diffraction of Light Waves

Though this question is not being asked for long questions, it is an important topic for short questions. Differences of diffraction with interference is among frequently asked long question in HSEB Physics Grade 12 exam.

Definition: The phenomenon of bending of light round the corners and spreading into the regions of the geometrical shadow is called diffraction. (It occurs with all waves including sound waves, water waves, and electromagnetic waves such as visible light, x-rays and radio waves.)

Jan 7, 2012

Elasticity Note

The weather is getting as romantic as the cold increases. Wow!!
How about dating with Physics?
Hmm, You won't disagree

Here is another update for the day. Its the updated version of one of our previous notes that is, note of Elasticity. Please be advised that, this is not the final update of the note. We shall be notifying about the future updates through the blog. The following changes have been made with the notes with the update.

Dec 30, 2011

Important Questions with answer - Physics - Grade 11

important-questions-with-answers-for-class-11-physicsHello buddies,
We would like to wish you all a prosperous Happy New Year 2012. Hope all of you will do great in your upcoming exams.

Here is an update for science students. This PDF notes consists some important questions with answers from a small portion of the chapter Heat and Thermodynamics, Grade XI, Physics.

Dec 21, 2011

Note for Elasticity - Physics - Grade XI

Hello all,
How are spending your winter?
Here is an update for you. Hope you will like it. This is a PDF note for Elasticity - Physics - Class 11. Though it is not complete, but it will surely help you to prepare for your exam.

Dec 14, 2011

Acid Rain and Greenhouse Effect

What is Acid Rain? How is it Caused?

Generally, acid rain means the rain of water containing excessive amount of acids.
Oxides of Slulphur, Carbon, and Nitrogen are major gaseous pollutant of air. These oxides are produced mainly by the combustion of fossil fuels, power plants, automobile exhaust, domestic fire etc. These oxides make layers and remains in the atmosphere. During rain, they react with water to form acids like Sulphuric acid, Nitric acid, Nitrous acid which then comes to the earth surface as acid rain or remain in the atmosphere in clouds or fogs.