Chat

Suchandrima Chowdhury

Teacher of physics

Feb 09, 2012 | Closed

CBSE Xth Board physics examination (Session IV)

51 questions answered

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how does magnification vary in the image formation by concave and convex mirrors and lenses? Asked by: Mansi
it will depend on the position of object. visit:http://www.topperlearning.com/student/topic/Mjc2/CBSE-Class%20X-Physics-Human%20eye%20&%20colourful%20world-Scattering%20of%20Light idea will get clear if u explore this site.
How does the power of a convex lens vary, if the incident red light is replaced by violet light? Asked by: GARIMA
power of convex lens ie the focal length is dependent on the refractive index of the medium of which the prism is made of. and refractive index depends on the colour of light . so it will always change for red light.
why there is no dispersion of light through a rectangular glass slab? Asked by: karan singh
yes there also dispersion takes place but recombination also takes place. as a rectangular glass slab can be regarded as combination of 2 prisms : one erect next inverted. so the dispersed rays get recombined after passing through it.
State the condition under which the terminal potential difference across a battery and its e.m.f are equal Asked by: GARIMA
In its ideal form, the cell can be modelled as the emf generator in series with a resistance known as the internal resistance of the cell. The other two ends available: one from the generator and the other from the internal resistance both provide the two terminals you refer to (+ive and -ive).
What is band pass filter? Asked by: GARIMA
A band-pass filter is a device that passes frequencies within a certain range and rejects (attenuates) frequencies outside that range. Optical band-pass filters are of common usage.
Where are the images formed in a concave and a convex lens? Asked by: Mansi
visit and if possible subscribe : http://www.topperlearning.com/student/topic/Mjc2/CBSE-Class%20X-Physics-Human%20eye%20&%20colourful%20world-Scattering%20of%20Light u'll surely get great help.
what is astigmatism and how is it corrected? Asked by: KARAN SINGH
Astigmatism is a vision condition that causes blurred vision due either to the irregular shape of the cornea, the clear front cover of the eye, or sometimes the curvature of the lens inside the eye. An irregular shaped cornea or lens prevents light from focusing properly on the retina, the light sensitive surface at the back of the eye. As a result, vision becomes blurred at any distance. Astigmatism may be corrected with eyeglasses, contact lenses, or refractive surgery.
i am a student of class 11th i need help in defining what is simple harmonic motion. Asked by: chetan kumar
simple harmonic motion is the harmonic motion in which frequency and amplitude remains same. restoring force is proportional to the displacement and is in opposite direction.
What is lateral inversion? Asked by: Mansi
Lateral inversion is the reveasal experienced by the image formed in a flat mirror. Lateral inversion is the effect produced by a plane mirror in reversing images from left to right. As we observe our image on a plane mirror, we can see that our left side is at the right side of the image and our right side is at the left side of the image. It is also known as perversion.
why do stars appear to be higher than their actual position but not lower than their actual position? Asked by: karan singh
Because of refraction in the earth's atmosphere: The air density in the earth's atmosphere and therefore also the index of refraction of the earth's atmosphere decrease with increasing altitude. Snellius' law of refraction tells us that light is refracted towards the medium with higher index of refraction. Therefore, the light coming from any star that is not situated directly above the observer takes a curved path bent down towards the observer, arriving at the observer at a steeper angle than had it travelled on a straight line.
which is the best refresher for 10th class? Asked by: karan singh
as such there is nothing as the best refresher. but u can read from S chand and togethjer with publications.
If the radius of the gaussian surface enclosing a charge is doubled how does the electric flux through the gaussian surface change? Asked by: GARIMA
flux only depends on the charge enclosed and permitivity of the med,nothing else. so if radius increases also there would not be any change in the flux.
why there is increase in atomic size from top to bottom in group Asked by: vivek
Down the group, has the same number of electrons in the outer energy level as all the other atoms of that family The protons in the nucleus attract the valence electrons in the outer energy level because of opposite electrostatic charges. The strength of this attraction depends on the size of the charges, the distance between the charges, and the number of electrons in-between the nucleus and the valence electrons. The core electrons shield the valence electrons from the nucleus. The presence of the core electrons weakens the attraction between the nucleus and the valence electrons. This weakening of the attraction is called the shielding effect. The amount of shielding depends on the number of electrons between the nucleus and the valence electrons. The strength with which the nucleus pulls on the valence electrons can pull the valence shell in tighter when the attraction is strong and not so tight when the attraction is weakened. The more shielding that occurs, the further the valence shell can spread out. So atomic size increases down the group
rR there any derivations in semiconductor devices & communiucation . if so plz tel which r they Asked by: GARIMA
as such there is no direct derivation except: 1. AM wave filter process but there are many direct questions are asked, like: pn jn diode, forward reverse bias, uses of diodes, transistor working and all applications, types of propagation:sky , ground,land in detail,
what r waves & their frequency??? Asked by: john
Wave is the transfer of energy from one place to another. Waves are the transverse & longitudinal waves. There are three type of waves: 1)Mechanical waves require a material medium to travel (air, water, ropes). These waves are divided into three different types. Transverse waves cause the medium to move perpendicular to the direction of the wave. Longitudinal waves cause the medium to move parallel to the direction of the wave. Surface waves are both transverse waves and longitudinal waves mixed in one medium. 2)Electromagnetic waves do not require a medium to travel (light, radio). 3)Matter waves are produced by electrons and particles. The frequency of wave is more means more waves.
could you plz give me some imp ways or tricks for organic conversions Asked by: ayush singh
ask in chemistry session.
i am student of class 12 . i want to know which reader one should follow to get good marks and how to learn formulas Asked by: sayma
list out formulas from each chapter and put them together. also mention their applications in short there. learn and go through every day. practise numericals. study hard. first NCERT, pradeeps next...then HCVerma.
I GET CONFUSED ABOUT MIRROR SIGN CONVENTION. PLZ HELP ME OUT............................ Asked by: RIYA
Spherical Mirrors Lenses Focal Length (f) + for concave mirrors + for a converging lens - for convex mirrors - for a diverging lens Object Distance (do) + if object is in front of the mirror (real object) + if the object is to the left of the lens (real object) - if object is behind the mirror (virtual object) * - if the object is to the right of the lens (virtual object) * Image Distance (di) + if the image is in front of the mirror (real image) + for an image (real) formed to the right of the lens by a real object - if the image is behind the mirror (virtual image) - for an image (virtual) formed to the left of the lens by a real object Magnification (m) + for an image that is upright with respect to the object + for an image that is upright with respect to the object - for an image that is inverted with respect to the object
what is the dimentional formula of area og trapezium???? Asked by: yukti
L to the power 2.
what is the difference between gravity and gravitation. Asked by: chottu kumar
gravity is termed as force of attraction by earth and gravatation is the force of attraction between any two objects
waht is the actual use of limits @ deivatives@ what is meant by torque? Asked by: rockey
torque is the rotational effect of force. when the object is fixed at some point or axis, and force is applied on it, then the effect of force depends : on the force ,as well as the perpendicular dist of the application of force from fixed axis. torque= cross product of force x perpendicular dist of force from the fixed axis.
1. What is the net flux through a closed surface enclosing an electric dipole? Asked by: GARIMA
Net charge on an electric dipole is zero . If the closed surface encloses a zero charge so net flux will also be zero
why red light has greater wavelength with respect to other colour of light Asked by: chottu kumar
blue light puts off more energy when looking at the Electromagnetic spectrum as a whole from the right to left (or from highest wavelength and lowest frequency (i.e radio waves) E = hc / wavelength So, red color has more wavelength & less energy than other colors.
protozoa reproduce by both binary and multiple fission. which is better among these and why? Asked by: karan singh
ask in bio chat.
what is physics? Asked by: ashok kumar
Physics is often described as the study of matter and energy. It is concerned with how matter and energy relate to each other, and how they affect each other over time and through space. Physicists ask the fundamental questions how did the universe begin? how and of what is it made? how does it change? what rules govern its behavior? Physicists may be roughly divided into two camps: experimental physicists and theoretical physicists
I am a student of class X , I am facing problems in the chapter Human Eye and the colourful world.. I end up writing wrong reasons every time ... any suggestions for me. Why is the colour of sky blue ? How is rainbow fomed ? Why is sky red during sunset / sunrise ? Asked by: Samarth Mishra
visit or subscribe: http://www.topperlearning.com/student/topic/Mjc2/CBSE-Class%20X-Physics-Human%20eye%20&%20colourful%20world-Scattering%20of%20Light watch the videos and solve the qs. idea will be surely clear.
Two nuclei have mass numbers in the ratios 1:8. What is the ratio of their radii? Asked by: GARIMA
Nuclear radius is directly proportional to the cube of mass number or atomic mass. So Ratio of radii will be 1:2
What is the effect on the interference pattern in Youngs double shift experiment when :- i. Screen is moved closer to the plane of slits. ii. Separation between two slits is increased. iii Monochromatic Red light is replaced by blue light. Asked by: GARIMA
we know that the fringe width=wave length of light x D/d D=distance of screen from slit d= distance between the slits. i. as D decreases fringes will be narrower. ii. as d increases, fringes again become closer. iii. red light has wavelength more so fringe widths will become more.
can similarly charge bodies ever attract each other explain? Asked by: GARIMA
Yes. This can happen when the charge on one body is very large as compared to the charge on the other body, because larger charge will induce opposite charge on the smaller body and thus attracts it.
what is the appropriate definition of charge. Asked by: chottu kumar
A form of charge, designated positive, negative, or zero, found on the elementary particles that make up all known matter Electric charge is a basic property of elementary particles of matter. The protons in an atom, for example, have a positive charge, the electrons have a negative charge, and the neutrons have zero charge.
what is total internal reflection in a water droplet ? Asked by: tanya
Light ray experience the total internal reflection in the water droplet & forms a rainbow.
What is the advantage of FM over AM. Asked by: GARIMA
1.Lesser distortion. Frequency modulated wave is less susceptible to intereferences from buildings, traffic etc which provides improved signal to noise ratio (about 25dB) w.r.t. to man made interference. 2. Waves at higher frequencies can carry more data than the waves at low frequency. 3.Smaller geographical interference between neighboring stations. 4.Less radiated power. 5.Well defined service areas for given transmitter power.
What is critical angle? Asked by: Mansi
Critical angle is angle of incidence above which total internal reflection occurs.
What are the uses of concave and convex mirrors? Asked by: Mansi
concave mirror: 1. shaving mirror,2. dentist's mirror...to see larger image of face and mouth. 3. in head lioghts to make light parallel. convex mirror: 1. rare view mirror of vehicle.
Define total internal reflection. Asked by: Mansi
Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle and with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is greater than the critical angle, no light can pass through and all of the light is reflected.
what is mirage. Asked by: chottu kumar
Mirage is an optical illusion caused due to Total Internal Reflection.It occurs during summers and especially in deserts. Cold air is denser than warm air and has therefore a greater refractive index. As light passes from colder air across a sharp boundary to significantly warmer air, the light rays bend away from the direction of the temperature gradient. When light rays pass from hotter to cooler, they bend toward the direction of the gradient. If the air near the ground is warmer than that higher up, the light ray bends in a concave, upward trajectory.
what is genetic drift? Asked by: Parul Agarwal
this is bio qs. Genetic drift—along with natural selection, mutation, and migration—is one of the basic mechanisms of evolution.
wat is the difference between wave front & ray Asked by: GARIMA
Wavefront is the portion of a wave envelope that is between the beginning zero point and the point at which the wave reaches its crest value, as measured either in time or distance. a ray is an idealized narrow beam of light. Rays are used to model the propagation of light through an optical system
two copper spheres of the same radii ,one hollow & other solid are charged to the same potential. Which of these two will hold more charge Asked by: GARIMA
charge will always be stored on the surface of the sphere. as the two have same radius and same pot, capacity will be same. as C=Q/V Q=CV capacity will be same as the radius and the pot same.
explain the working of SONAR. Asked by: pragya
Sonar (sound navigation and ranging) is the application of a sound wave propagated through some medium (like water) and the reception of reflected energy (the echo) to discover what is there The basic principles on which sonar relies are that sound moves at a steady rate through a given medium, such as air or water, and that certain types of objects produce certain types of sounds. With this knowledge, calculations can determine the distance to an object and identify it with reasonable certainty.
13. Name the reaction which takes place when a slow neutron beam strikes nuclei. Write the nuclear reaction involved. 2 Asked by: GARIMA
A result of nuclear fission or nuclear fusion, it consists of the release of free neutrons from atoms, and these free neutrons react with nuclei of other atoms to form new isotopes, which, in turn, may produce radiation. This will result in a chain reaction of nuclear radiation, which makes radiation dangerous and harmful over great areas of space.
What is tyndall effect? Asked by: Mansi
The term Tyndall effect is usually applied to the effect of light scattering on particles in colloid systems, such as suspensions or emulsions. Tyndall effect is used to tell the difference between the different types of mixtures, namely solution, colloid, and suspension. For example, the Tyndall effect is noticeable when car headlamps are used in fog. The light with shorter wavelengths scatters better, thus the color of scattered light has a bluish tint. This is also the reason why the sky looks blue: the light from the sun is scattered and we see the blue light because it scatters better.
1. What is the net flux through a closed surface enclosing an electric dipole? Asked by: GARIMA
as the net charge enclosed by the closed surface is 0, so the net flux=0 as from Gauss's law we know that net flux through any closed surface=net charge enclosed/epcilon not
7. An electron and a photon have same wavelength, which one of the two has more energy? Asked by: GARIMA
Electron will have more energy than photon because Energy is directly proportional to the mass of the particle E = mc2
Why is energy distribution of β-ray continuous? Asked by: GARIMA
When a nucleus beta-decays, it emits two particles at the same time: One is a beta particle; the other, a neutrino or antineutrino. With this emission, the nucleus itself undergoes a transformation, changing from one element to another. In the case of isotopes that β+-decay, each decaying nucleus emits a positron and a neutrino, simultaneously reducing its atomic number by one unit; for those isotopes that β−-decay, each nucleus emits an electron and an antineutrino while increasing its atomic number by one. In both classes of decay, the energy released by the nuclear transformation is shared between the two emitted particles. Though the energy released by a particular nuclear transformation is always the same, the fraction of this energy carried away by the beta particle is different for each decaying nucleus. (The neutrino always carries away the remainder, thus conserving energy overall.) When observed collectively, the decaying nuclei of a simple radioactive source emit their beta particles with a continuous distribution of kinetic energies covering the range from zero up to the total nuclear decay energy available
Why does the sky appears red at sunrise and sunset? Asked by: Mansi
"At sunrise and sunset, the sun's distance from the earth is far greater than at noon, so most of the VIBGYOR colours, excluding red, orange and sometimes yellow get refracted away by the atmosphere due to different wav The atmosphere tends to absorb higher wavelengths. The more atmosphere the light has to go through, the less higher wavelengths get through, so you are left with lower wave lenghts (red).
what is speed Asked by: ashok kumar
Speed is the rate of change of distance with time. Its a scalar quantity . It have no direction. Speed = Distance Traveled by an object/ Time taken
Mam, I am a student of class 12 cbse student. I didn't attend my collage even once because of mt health issues. Can you please guide me atleast from physics point of view, because no time left to prepare. please madam help me. Asked by: Hardik
u start with ray Optics chapter. it carries maximum weightage but easy to grasp. practise the diagrams. then do dual nature of matter,semiconductor.....easy and surely some qs u 'll get. study gauss's law and its application of it.cyclotron, transformer,moving coil galvanometer.
how does human ear work? Asked by: pragya
We have three parts of the ear. The first step is when the pinna collects external sounds that enter through the meatus or ear canal as sound waves. The ear drum begins to vibrate as these sound waves strikes. These vibrations pass through to the three ossicles of the middle ear (hammer, anvil and stapes) where they are amplified. As the transmission proceeds, the vibrations first hit the hammer, then the hammer pushes the anvil, and the anvil hits the stapes. The vibrations are finally interpreted as sound in the brain after being transmitted and transformed into nerve signals by the cochlea (snail shaped component of the inner ear). This is due to the connectivity of the oval window of the inner ear to the edge of the stapes. When the stapes vibrates, they always transmit the sound vibrations to the inner ear.
WHY DO STAR SEEMS TO BE HIGHER THAN ITS ACTUAL POSITION?WHY DO THEY DON'T APPEAR TO BE LOWER? Asked by: KARAN SINGH
when the light beam from the star reaches your eye, it's arriving from a direction that is slightly above the actual direction from the star, and the effect is that the star appears to be higher than it really is.
Can a plane mirror also be called a spherical mirror?if yes then how? Asked by: Mansi
plane mirror is a spherical mirror with infinite radius of curvature.that is why it can be said that it focuses light at infinity.