Human eye is the most important organ of our body which is an optical device that serves as our organ of sight. It consists of a tough fibrous membrane called sclera that protects the internal parts of the eye.
Cornea is the membrane covering the front of the eye that is bulged out and is responsible for the maximum refraction of the light that enters the eye.
Aqueous humour lies behind cornea that enables the eye to cope up with the atmospheric changes.
Iris forms the coloured part of the eye. It adjusts the size of the pupil, thereby controls the amount of light entering the eye.
The crystalline lens, lies behind Iris a biconvex structure that helps in fine adjustment to the refracted light so that it is focused on the screen of the eye, which is referred to as retina.
Ciliary muscle helps in adjusting the focal length of the lens by contraction or relaxing. Vitreous humour lies behind the lens which is a dense, clear, jelly like fluid which helps to maintain the shape of the eye and focus the image clearly on the retina.
Retina is actually a canopy of the nerve endings of the optical nerve through which images are converted into electrical impulses and transferred to the brain for realization of the image.
The eye can focus near objects as well distant objects and this is accommodation of the eye. The minimum distance of the object at which an eye can focus clearly is the near point the maximum is called the far point.
If an eye is unable to focus the nearby objects and is able to view clearly the far off objects, the defect is called hypermetropia or long sightedness and can be corrected by a suitable convex lens.
Faraday in 1831 first discovered that whenever the number it of magnetic lines of forces in a circuit changes, a emf is produced in the circuit and is known as induced emf and this phenomenon is known as Electro Magnetic Induction
If the circuit is closed one then a current flows through it which is known an induced current This induced emf and current lasts only for the time while magnetic flux is changing
We now illustrate two examples of the sort that Faraday and Henry performed
(i) Experiment I
Figure below shows a closed circuit containing coil of insulated wire.
Also note that circuit does not contain any source of emf so there is no deflection in the galvanometer
Figure 1. North pole of the magnet moving towards and away from closed circuit containing galvanometer in Faraday's experiment
If we move bar magnet towards the coil keeping the coil stationary with north pole of the magnet facing the coil (say) then we notice deflection in needle of the galvanometer indicating the pressence of the current in the circuit
This deflection observed is only for the time interval during which the magnet is in motion
Now if we begin to move the magnet in the opposite direction then the galvanometer needle is now deflected in the opposite direction
again if we move the magnet towards the coil ,with its south pole facing the coil,the deflection is now in opposite direction,again indicating that the current now setup in the coil is in reverse direction to that when the north pole faces the wire
A deflection is also oberved in galvanometer when the magnet is held stationary and circuit is moved away from the magnet.
It is further observed that faster is the motion of magnet ,larger is the deflection in the galavanometer needle.
From this experiment faraday convinced that magnet moving towards the coil one way has the same effect moving coil towards the magnet the other way.
(ii) Experiment -2
Figure-2 given below shows a primary coil P connected to the battery and a secondary coild connected to the galvanometer
This experiment shows that current flowing in primary coil generated current in secondary coil
Now we have replaced magnet of the previous experiment with a current carrying coil and expect to observe similar effect as current carrying coil produces magnetic field.
The motion of either of the coils shows deflection in the galvanometer.
Also galvanemter shows a sudden deflection in one direction when current was started in primary coil and in the opposite direction when the current was stopped.
Reflection of Light
Reflection is one of the unique properties of light. It is the reflection of light, which enables us to see any object.
Reflection: The bouncing back of rays of light from a polished and shiny surface is called reflection or reflection of light. It is similar to bouncing back of a football after colliding with a wall or any hard surface.
Laws of Reflection of light:
The angle of incidence and angle of reflection is equal.
The incident ray, reflected ray and normal to the point of reflection lie in the same plane.
The angle of incidence is denoted by 'i' and angle of reflection is denoted by 'r'. The law of reflection is applicable to all types of reflecting surface.
Mirror and Reflection of Light:
Mirror is a shiny polished object (glass) which reflects most of the rays of light falling upon it. One side of mirror is polished with suitable material to make the other side reflective.
Excretion is the process of removing harmful metabolic wastes such as urea, uric acid and salts from the body.
Excretion in organisms
Unicellular organisms, like amoeba, remove wastes by simple diffusion from the body surface into the surrounding water.
Lower multi-cellular organisms like flat worms use flame cells while earthworms use nephridia for excretion.
Higher multi-cellular organisms like fish, frogs, lizards, birds and humans use kidneys for excretion. Homeostasis is the tendency of the physiological system of higher animals to maintain internal stability of the body.
Excretory system in humans
The excretory system in human beings includes a pair of kidneys, a pair of ureters, a urinary bladder, and a urethra. This is also known as the urinary system.
Excretory substances can be ammonia, urea and uric acid.
a) Ammonia is generated as a result of oxidative deamination reactions occurring in the body. Ammonia is a toxic nitrogenous waste and need to be eliminated. It is very toxic to the body and requires more amount of water to excrete it. Aquatic organisms excrete ammonia as they have water around them. Terrestrial animals either convert ammonia into urea or uric acid. Ammonia reaches the liver, the key site which converts this ammonia into urea.
b) Urea is the excretory waste of human beings. As a result of amino acid metabolism, many nitrogenous wastes like ammonia. As ammonia is toxic to human body when retained, it is converted into urea by the liver. Urea is also called as carbamide. Urea, the main excretory product formed in the liver is carried away by the blood to kidneys.
c) Uric acid is a bicyclic, heterocyclic compound made by the combination of carbon, hydrogen, oxygen and nitrogen. It is formed in the body during protein metabolism. Animals that excrete their waste in the form of nucleic acid form shelled eggs which are permeable to soluble gases. Most of the terrestrial organisms which do not have much access to water excrete uric acid as their excretory product. e.g. Reptiles, Birds. In human beings, it is formed as a result of metabolism of food mainly containing purines. Uric acid formed dissolves in the blood and taken to kidneys for excretion. It is very concentrated and requires very less amount of water to be excreted along with it. Excess of uric acid in the blood causes the disease called as gout.
Dialysis is the process which involves separation of nitrogenous wastes from the blood artificially. Dialysis is performed using a device which removes nitrogenous wastes from blood in case of kidney failure.
An artificial kidney contains a number of tubes with a semi-permeable lining suspended in a tank filled with dialysing fluid.
The patient's blood is passed through these tubes.
During this passage, waste products from the blood diffuse into the dialysing fluid.
The purified blood is pumped back into the patient.
Excretion is also observed in plants. Plants get rid of excess water by the process of transpiration. Resins, gums and dead leaves are some excretory products of plants.
Transportation in plants
Plants obtain minerals from soil, water and fertilisers. Need for transportation in plants is to distribute water and nutrients to various parts. Transportation in a plant is a method of circulation of water and minerals from soil throughout the body of a plant.
Vascular tissues in transport
Vascular tissues like the xylem and phloem help in the conduction of water, minerals and nutrients throughout a plant's body.
a) Xylem is the vascular tissue extending from top to bottom of the plant.
Xylem tissue is present in the roots, stems and leaves.
It helps in the transport of water molecules and dissolved substances from the root hairs to aerial parts of the plant.
Xylem mainly comprises of tracheids, vessels, xylem parenchyma and xylem sclerenchyma.
The transport in xylem is unidirectional.
Xylem mostly occupies the centre of the vascular bundle.
The xylem transports water and minerals from the roots to the leaves.
Tracheids and vessels are interconnected to form a continuous system of water-conducting channels that reach all parts of a plant.
Cells in the roots take up ions to create a high ion concentration. This causes water to move into the roots.
b) Phloem is the vascular tissue which transports food molecules to the place of necessity in the plant.
The elements in the phloem are sieve elements, fibres, phloem parenchyma and companion cells.
The transport in the phloem tissue is bidirectional.
It forms vascular bundles in association with xylem.
Phloem occupies the edges of the vascular bundle.
Transpiration is the evaporation of water from the leaves in the form of water vapour. Transpiration occurs in leaves through special structures present on them called as stomata. Transpiration is the process which helps the plant in many ways.
Transpiration always occurs against the gravity.
Transpiration involves mainly the xylem cells which become active during absorption process by the roots.
Excess water is removed from the cells of the plant to prevent plant decay.
Osmotic balance of the cell is maintained by the process of transpiration.
Transpiration is the process which helps all the parts of the plant to cool them.
Transpiration helps in the distribution of dissolved substances to all parts of the plant.
Translocation is the process of the movement of synthesised products from the leaves to the roots and other parts of a plant's body through the phloem.
The phloem is a conducting tissue for nutrients from the leaves to the other parts of a plant's body. Translocation does not always occur against gravity.
Translocation involves both xylem and phloem cells to carry the synthesized food materials within the plant.
As sugar is synthesised in the leaves by the process of photosynthesis, a high concentration of organic substance inside the phloem cells of the leaf creates a diffusion gradient by which more water is sucked into the cells.
Translocation takes place in the sieve tubes, with the help of adjacent companion cells.
Types of transport
a) Passive transport can be explained by diffusion. Diffusion is the movement of molecules in a random manner that is from a region of higher concentration to a region of lower concentration. Diffusion involves no expenditure of energy as it does not involve any semi-permeable membrane. Diffusion is a process which can occur in all media which involve solid, liquid and gaseous molecules. Diffusion is a passive process which occurs in the transportation of substances in plants.
b) Active transport involves the movement of ions against concentration gradient through membranes. It is carried out with expenditure of energy. Active transport requires carriers for transport across the cell membrane. Active transport is involved in translocation of minerals in the plant body and accumulation in the plant cells. e.g. Glucose molecules in the leaves are transferred to the phloem tissue using energy from ATP.
c) Osmosis is the process of diffusion of solvent particles from the region of less solute concentration to a region of high solute concentration through semi-permeable membrane. Osmosis can be observed in human beings in the phenomenon of membrane transport. Cells possess cell membranes. These cell membranes are selectively permeable and many molecules move in and out of the cell by the process of osmosis.
Types of solutions
Osmosis can occur in hypertonic solutions, hypotonic solutions and isotonic solutions. Sometimes cell can even undergo the phenomenon called as plasmolysis.
Hypotonic solutions are the ones which have a lower concentration of solute than the cell. Water diffuses into the cell to balance the solute concentration on either side (outside and inside) equal. Here the cell swells up due to entry of water.
Hypertonic solutions are the ones which have higher solute concentration than the cell. Water moves out of the cell through cell membrane to balance the concentration of the solute on either side. It results in cell shrinking .This may also lead to desiccation of the cell.
Isotonic solutions have the same concentration of the solute as the cell. Water moves in and out of the cell with no net change.
Sigma and Pi Bond
A sigma bond is a type of covalent bond formed by the axial overlapping of two half filled atomic orbitals. The atomic orbitals undergoing sigma bond formation overlap along the internuclear axis and involve head on head overlap. The electron cloud is thus cylindrically symmetrical about the internuclear axis.
Three types of these axial overlaps are possible. These are between the s and the pz orbitals and are as under.
s-s overlap: It involves the overlap of two half filled s-orbitals approaching towards each other to form a bond. The bond so formed is called as s-s sigma bond.
s-p overlap: It involves the mutual overlap of half filled s-orbital of one atom with half filled pz -orbital of another atom. The bond so formed is called as s-p sigma bond.
p-p overlap: It involves the mutual overlap of half filled pz -orbital of one atom with half filled pz -orbital of another atom. The bond so formed is called as p-p sigma bond.
A pi (π) bond is formed by sideways overlapping as the axes of the orbitals remain parallel to each other, and perpendicular to the inter-nuclear axis. A px- px and a py- py bond are pi (π) bond.
States of Matter - Introduction
Everything in this universe is made up of matter. Matter is defined as any substance that has mass, occupies volume and may be perceived by the senses.
Exception: Phenomena like heat, electricity, light, sound, magnetism, vaccum, shadow are not matter because they have no mass and does not takes up space.
Matter is made up of small particles. The particles of the matter are very small. We cannot see them even with a high power microscope.
The particles of the matter have following characteristics
Matter is made up of small particles.
The particles in the matter have spaces between them. This space is called inter molecular space.
The particles in the matter are moving in nature, because the particles of a matter have kinetic energy. The motion of the particles increases with an increase in temperature.
The particles in the matter attract each other, but this mutual force of attraction is effective only when the particles are very close to each other. In solids the particles are closely packed and hence they have greater intermolecular forces attractions while in gases, the particles are loosely held. Hence they have weak forces of attractions.
A chemical equation is helpful to understand a chemical reaction in an easy way.
In a chemical equation the masses of reactants and products may or may not be equal. But according to law of conservation of mass "the total mass of the reactants and the products should be equal".
So in order maintain the law true it is necessary to balance a chemical equation.
Steps involved in balancing of chemical equation:
Determining the reactants and products in a reaction.
Counting the number of atoms of each element on both sides of the equation.
Selecting the elements that occur for the least number of times in the equation.
Balance atoms of each element on both sides of the reaction.
Always leave hydrogen and oxygen for last to balance.
Balance the hydrogen atoms lastly followed by balancing of oxygen atoms.
Space and Volume - 01
Volume of a solid is the measure of the space occupied by it. The volume of substance that can be stored by the object is called its capacity. Volume is measured in cubic units.
Space and Volume - 01
A cube whose length, breadth and height are all equal is called a cube.
Consider a cube of edge a units.
Volume of cube = a3 cubic units
Space and Volume - 03
A cuboid is a solid bounded by six rectangular plane faces.
Consider a cuboid of length, breadth and height are l, b and h respectively.
Volume of cuboid = lbh cubic units
Topic- The Human Eye
Question No-1: Where the image formed in the eye?
d) Crystalline lens
Question No-2: The only living tissue which does not contain a blood vessel in the human body is the________.
Topic- Faraday's Experiments
Question No-8: The magnetic flux linked with a coil is inversely proportional to the _____.
a) Area of cross-section
b) Number of turns
c) Magnetic field
Question No-9: When the magnetic field is parallel to a surface, then the magnetic flux through the surface is _____.
b) small but not zero
c) infinite but not zero
Topic- Reflection of Light
Question No-4: When light is incident on a polished surface _______reflection takes place.
Question No-9: What is the angle between the incident and reflected rays when a ray of light is incident normally on a plane mirror?
Question No-1: Presence of excess of urea in blood is called_________.
Question No-2: Flame cells are excretory structures of________.
Topic- Transportation in plants
Question No-1: Water and nutrients are absorbed from soil by
d) Root hairs
Question No-2: In plants, the channel that transports nutrients absorbed from soil is called
d) Root hairs
Topic- Sigma and Pi Bond
Question No-1: Linear combination of two hybridised orbital belonging to two different atoms results in the formation of ________.
a) Pi bond
b) Delta bond
c) Double bond
d) Sigma bond
Question No-2: The half of the difference between the number of electrons in bonding and antibonding molecular orbital is called ________.
a) Molecular order
b) Electronic order
c) Bonding Capacity
d) Bond order
Topic- States of Matter - Introduction
Question No-1: A sample of CO with a volume 500 ml at a pressure of 760 mm is to be compressed to a volume of 450 ml. What additional pressure is required to accomplish the change, if the temperature is kept constant?
a) 98.2 mm
b) 74.5 mm
c) 84.4 mm
d) 69.23 mm
Question No-2: The volume of a gas is 10.00 L at S.T.P. Find the volume of the gas at 100°C and 5.0 atm pressure.
a) 6.90 L
b) 2.73 L
c) 5.36 L
d) 7.07 L
Topic- Balancing Equation
Question No-1: How the colour changes when the gases after thermal decomposition of ferrous sulphate come in contact with an acidified solution of potassium dichromate?
a) Green to Orange
b) Orange to green
c) Blue to Green
d) Red to colourless
Question No-2: What is the color of solid ferrous sulphate?
c) Light green
d) Light yellow
Topic- Space and Volume - 01
Question No-1: The volume is also known as ________ .
c) containing element
Question No-3: Volume is expressed in
d) All of the above.
Topic- Space and Volume - 02
Question No-8: The formula of volume of cube is ________.
b) l x b x h
c) π r2 h
d) all the above
Question No-1: Each side of a cube is 2y cm long. What is the volume of the cube?
a) 8y3 cm3
b) 6y cm3
c) 4y3 cm3
d) 2y cm3
Topic- Space and Volume - 03
Question No-2: Cuboid has _______ faces.
d) All of the above
Question No-18: Find the volume of the cuboid whose length is 6cm, breadth is 3 cm, height is 4 cm?
a) 72 cm3
b) 62 cm3
c) 101 cm3
d) 73 cm3
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