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All Question Answers

Give reason of Failure of Thomson’s Atom Model

It had to be discarded, because of the following reasons: It could not explain the origin of the spectral lines in the form of series as in case of hydrogen atom. It could not account for the scattering...

Class 12 Subject: Chemistry Topic: Electrochemistry
What is Thomson’s Atom Model?

The positive charge is uniformly distributed over the entire sphere and the electrons are embedded in the sphere of positive charges just like seeds in a watermelon or plums in the pudding.  For this reason, Thomson’s...

Class 12 Subject: Chemistry Topic: Electrochemistry
What is modulation? Why is it needed in communication?

Modulation is the process of superimposing message signal on carrier wave. Need:·         Prevent signal loss·         Allow long-distance transmission ·         Reduce antenna size

Class 12 Subject: Physics Topic: Ray optics and optical Instruments
Write characteristics and uses of electromagnetic waves.

·         Travel at speed of light·         Transverse in nature·         Don’t require medium Uses:·         Radio waves → communication ·         X-rays → medical imaging

Class 12 Subject: Physics Topic: Magnetism
State Faraday’s laws of electromagnetic induction.

·         1st Law: A changing magnetic flux induces an emf.·         2nd Law:Induced emf=−dϕ / dt Negative sign = Lenz's law (opposes the change).

Class 12 Subject: Physics Topic: Magnetism
Compare solenoid and bar magnet fields.

The magnetic field of a long solenoid resembles that of a bar magnet — it has a north and south pole and similar field line patterns.

Class 12 Subject: Physics Topic: Magnetism
State Kirchhoff’s laws and apply them to a Wheatstone bridge.

·         Kirchhoff’s Current Law (KCL): Total current entering a junction = total current leaving.·         Kirchhoff’s Voltage Law (KVL): Algebraic sum of all potential differences in a closed loop is zero. Used i...

Class 12 Subject: Physics Topic: Ray optics and optical Instruments
What are the laws of Reflection?

·         Two fundamental laws govern reflection.The angle of incidence (I) equals the angle of reflection (r).At the point of incidence, the incident ray, reflected ray, and the normal to the reflecting surface lie i...

Class 12 Subject: Physics Topic: Ray optics and optical Instruments
Magnifying power of a simple microscope is inversely proportional to the focal length of the lens. What then stops us from using a convex lens of smaller and sm...

The convex lens's focal length cannot be reduced by a more significant amount. This is because making lenses having tiny focal lengths is not easy.  Spherical and chromatic aberrations are created by a convex le...

Class 12 Subject: Physics Topic: Ray optics and optical Instruments
In viewing through a magnifying glass, one usually positions one's eyes very close to the lens. Does angular magnification change if the eye is moved back?

Yes, the angular magnification varies. When the length between the eye and a magnifying glass rises, the angular magnification reduces slightly because the subtended angle at the eye is imperceptibly less than the le...

Class 12 Subject: Physics Topic: Ray optics and optical Instruments

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