Physics content-2

 

1.       What is wave motion?

      Wave motion is the transfer of energy and momentum from one point to another through a medium (or vacuum) via periodic oscillations or vibrations, without the permanent transfer of matter.

2.       What is Circular motion?

       Circular motion is the movement of an object along a circular path at a constant or variable speed, where the object maintains a fixed distance from a central point.

Or

        Circular motion is a moment of an object along the circumference of a circle or rotation along a circular path. It can be uniform with constant angular rate of rotation and constant speed or non-uniform with changing rate of rotation.

3.       Mention the types of circular motion.

·         Uniform circular motion: An object moves in a circle with constant speed and a constant angular rate.

Example: A ceiling fan at a constant speed, a satellite orbiting Earth at a constant altitude, or a stone tied to a string being whirled at a steady pace.

·         Non-uniform circular motion: An object moves in a circle with changing speed.

Example: A car speeding up or slowing down on a circular track, a roller coaster in a vertical loop, or a vertical circular motion where speed varies due to gravity.

4.       What are the differences between longitudinal and transverse wave?

Transverse Waves	Longitudinal Waves
1.       Transverse waves consist of crests and troughs.	1.       Longitudinal waves consist of compressions and rarefactions.
2.       There are no pressure variations.	2.  There is a pressure variation throughout the medium.
3.       They can be propagated through solids and surfaces of liquids but not in gases.	3.They can be propagated through solids, liquids as well as through gases.
4.       The particles of the medium vibrate at right angles to the direction of wave propagation.	4.The particles of the medium vibrate          parallel to the direction of the wave          propagation.
5.       There is no change in density of the medium.	5.There is a change in density of the            medium.
6.       Light waves are an example of transverse waves.	6.Sound waves are an example of            longitudinal waves.

 

5.       What is electromagnetic induction? Mention the factors on which an induced emf depends.

       Electromagnetic Induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field. The induction of electromotive force by the motion of a conductor across a magnetic field or by a change in magnetic flux in a magnetic field. It has found many applications, including electrical components such as inductors and transformers and devices such as electric motors and generators.

 Or

 Electromagnetic induction is the process of generating an electromotive force (EMF or voltage) and current in a conductor, such as a wire coil, by exposing it to a changing magnetic field.

Factors on which an induced emf depends:

Ø  Rate of change of Magnetic flux

Ø  Number of turns in the coil.

Ø  Magnetic field strength

Ø  Area of the coil.

Ø  Relative motion/Speed

Ø  Orientation of the coil.

6.       State ‘Faradays laws’ of electromagnetic induction.

First law: Whenever the number of magnetic lines of force (magnetic flux) passing through

a circuit changes, an emf is produced in the circuit called induced emf. The induced emf          persists only as long as there is change of flux.

Second law: The included emf is given by the rate of change of magnetic flux linked with the circuit i.e.,

a negative sign indicates that induced emf opposes the change of flux.

7.       What is alternative current? Write its graphical representation.

Alternating current (AC) is a type of electric current where the flow of charge reverse direction and changes magnitude periodically over time, usually in a sine wave pattern.

8.       Explain principle and construction and working of transformer.

         Transformer electrical transformer is a static electrical machine which transforms electrical power from one circuit to another circuit, without changing the frequency. Transformer can increase or decrease the voltage with corresponding decrease or increase in current. Working principle of transformer

      The basic principle behind working of a transformer is the phenomenon of mutual induction between two windings linked by common magnetic flux.

        The figure at right shows the simplest form of a transformer. Basically, a transformer consists of two inductive coils; primary winding and secondary winding. The coils are electrically separated but magnetically linked to each other. When, primary winding is connected to a source of alternating voltage, alternating magnetic flux is produced around the winding. The core provides magnetic path for the flux, to get linked with the secondary winding. Most of the flux gets linked with the secondary winding which is called as 'useful flux' or main 'flux', and the flux which does not get linked with secondary winding is called as 'leakage flux'. As the flux produced is alternating (the direction of it is continuously changing), EMF gets induced in the secondary winding according to Faraday's law of electromagnetic induction. This emf is called 'mutually induced emf', and the frequency of mutually induced emf is same as that of supplied emf. If the secondary winding is closed circuit, then mutually induced current flows through it, and hence the electrical energy is transferred from one circuit (primary) to another circuit (secondary). Basic construction of transformer Basically a transformer consists of two inductive windings and a laminated steel core. The coils are insulated from each other as well as from the steel core. A transformer may also consist of a container for winding and core assembly (called as tank), suitable bushings to take the terminals, oil conservator to provide oil in the transformer tank for cooling purposes etc. The figure at left illustrates the basic construction of a transformer. In all types of transformers, core is constructed by assembling (stacking) laminated sheets of steel, with minimum air-gap between them (to achieve continuous magnetic path). The steel used is having high silicon content and sometimes heat treated, to provide high permeability and low hysteresis loss. Laminated sheets of steel are used to reduce eddy current loss. The sheets are cut in the shape as E, I and L. To avoid high reluctance at joints, laminations are stacked by alternating the sides of joint. That is, if joints of first sheet assembly are at front face, the joints of following assemble are kept at back face.

9.       What is electronic configuration? Explain the differences of shell and orbit.

    Electronic configuration is the systematic distribution of an atom’s r molecule’s electrons into atomic shells and subshells (Orbitals) at different energy levels.

Shell	Orbit
1.       Shell is the pathway followed by electrons around an atom’s nucleus	1.       Orbital is a mathematical function that describes the wave like behaviour of an electron.
2.       Given the principal quantum number.	2.       Given the magnetic quantum number.
3.   Can hold up a maximum of 32             electrons.	3. Can hold up to a maximum of 2             electrons.

10.   What is chemical reaction?

         A chemical reaction is a process where one or more substances (reactions) rearrange their atomic structures to form new substances (products) with different chemical properties.

11.   Explain saturated and unsaturated hydrocarbons with examples.

Saturated hydrocarbons: Saturated hydrocarbons are organic compounds consisting entirely of hydrogen and carbon atoms linked exclusively by single covalent bonds, known as alkanes. They are “saturated” because they contain the maximum possible number of hydrogen atoms for the amount of carbon present, typically following the formula C_nH_2n+2. These molecules are generally less reactive than unsaturated hydrocarbons.

Examples: Methane (CH₄), Ethane (C₆H₆), Propane (C₃H₈), Butane (C₄H₁₀), Octane (C₈H₁₈),

Unsaturated hydrocarbons: Unsaturated hydrocarbons are organic compounds consisting of carbon and hydrogen that contain at least one carbon-carbon double (C=C) or triple (C) bond. Because of these multiple bonds, they hold fewer hydrogen atoms that their maximum capacity, making them more reactive than saturated compound and capable of undergoing addition reactions.

Examples: Ethene (Ethylene) (CH₂=CH₂), Propene (Propylene)(CH₃CH=CH₂), Acetylene (Ethyne) (CHH),

12.   Explain the following by giving examples

a)      Combination chemical reaction b) Decomposition chemical reaction.

Or Explain types of chemical reactions with examples

a)       Combination chemical reaction: A chemical combination reaction (or synthesis reaction) occurs when two or more elements or compounds react to form a single new compound. Generally represented as A+B--> AB, these reactions frequently release energy (exothermic) and are characterized by a simpler structure combining into a more complex one. 

Examples: 1) Formation of water:

                        2H₂(g) +3O₂(g)----> 2H₂O (l)

                    2) Rusting of Iron:

                          4Fe (s) + 3O₂(g)----> 2Fe₂O₃(s)

b)      Decomposition chemical reaction: A decomposition reaction is a reaction in which a compound breaks down into two or more simpler substances. The general form of a decomposition reaction is: AB---->A+B. Most decomposition reactions require an input of energy in the for of heart, light, or electricity.

Examples:         2Fe (OH)₃             -----> Fe₂     +               3H₂O

                     Ferric hydroxide       Ferric oxide             Water

                        2H₂O    ----->     2H₂     +            O₂

                              Water                Hydrogen      Oxygen

13.   Write the electronic configuration of the following:

a)      Oxygen   b) Hydrogen    c) Nitrogen      d) Sodium       e) Chlorine

^a)                Oxygen – 1s² 2s² 2p⁴   

^b)               Hydrogen ^– 1s¹

^c)                 Nitrogen – 1s² 2s² 2p³

^d)               Sodium-1s² 2s² 2p⁶ 3s¹

^e)               Chlorine-1s² 2s² 2p⁶ 3s² 3p⁵

14.   What are saturated hydrocarbons? Mention the differences between saturated and unsaturated hydrocarbons.

Saturated hydrocarbons: Saturated hydrocarbons are organic compounds consisting entirely of hydrogen and carbon atoms linked exclusively by single covalent bonds, known as alkanes.

SATURATED HYDROCARBONS	UNSATURATED HYDROCARBONS
1.       Saturated hydrocarbons are hydrocarbons with only single covalent bonds.	1.       Unsaturated hydrocarbons are hydrocarbons with multiple covalent bonds.
2.       Include alkanes	2.Include alkenes, alkynes, and aromatic hydrocarbons.
3. Less reactive	3.More reactive
4. Have a less amount of carbon and            high amount of hydrogen.	4. Have a high amount of carbon and less       amount of hydrogen
5. Burning in air result in a blue, non-            sooty flame	5.Buring in air result a yellow, sooty flame,
6. Usually obtained from fossilized plant            and animal materials,	6.Usually obtained from plants.

 

15.   What are allotropic forms? Explain allotropic forms of carbon.

      Diamond, graphite, fullerenes and graphene are the allotropes of carbon which are chemically identical and differ markedly in their physical properties. This phenomenon is called allotropy. The phenomenon of the existence of an element in two or more forms has different physical properties, but identical chemical properties are called allotropy, and the different forms are called Allotropes

Diamond

      Structure:

·         Diamond is a colorless transparent substance having extraordinary brilliance.

·         Diamond is quite heavy.

·         Diamond is extremely hard. It is the hardest natural substance known.

·         Diamond does not conduct electricity.

·         Diamonds can be artificially made by subjecting pure carbon to very high pressure and temperature. These are called synthetic diamonds.

        Uses:

·         Diamonds are used in cutting instruments like glass cutters; saw for cutting marble and in rock drilling equipment.

·         Diamonds are used for making jewelry.

Graphite:

         Structure:

·         Graphite is a greyish-black opaque substance.

·         Graphite is soft and slippery to touch.

·         Graphite conducts electricity.

          Uses:

·         The softness of graphite helps in the making of lubricant for fast moving parts of machinery.

·         As Graphite is a good conductor of electricity, it helps in the making of electrodes or graphite electrodes in dry cells and electric arcs.

·         Graphite helps in developing cores of pencils i.e. pencil leads and black paints.

Buckminsterfullerene

·         An allotrope of carbon-containing clusters of 60 carbon atoms joined together to form spherical molecules is Buckminsterfullerene.

Structure:

·         Its formula is C60 (C- sixty).

·         Buckminster-fullerene is a football-shaped spherical molecule.

·         It has 60 carbon atoms rearranged into interlocking hexagonal and pentagonal rings of carbon atoms.

·         Buckminsterfullerene is a dark solid at room temperature.