Param Himalaya - परम हिमालय

DOMESTIC ELECTRIC CIRCUITS Magnetism of Class 10 DOMESTIC ELECTRIC CIRCUITS In our homes, we receive supply of electric power through a main supply which is also called mains. The various other features of domestic electric currents are : DOMESTIC ELECTRIC CIRCUITS In our homes, we receive supply of electric power through a main supply which is also called mains. The various other features of domestic electric currents are : FEATURE OF DOMESTIC CIRCUIT: Electric cable or overhead wires The electric power to a house is supplied either through overhead wires or through underground cables. The cable has three separate insulated wires: 1. Live wire (or phase or positive). 2. Neutral wire (or negative). 3. Earth wire. The live wire has usually red insulation cover, neutral wire has black insulation cover and the earth wire has green insulation cover. As per the new International Convention, live wire has brown coloured insulation cover whereas neutral and earth wires have light blue and gre...

Advantage of Alternating current (AC) over Direct current (DC) : Alternating current can be transmitted over long distances without much loss of electrical energy. AC is easy and cheaper to generate than DC. AC can be transferred to long distance as compared to DC. Power loss in AC is less as compared to DC during transmission. AC can be easily converted into DC

Direct current and Alternating current and it's Difference : Direct current :  If the Current flows in One Direction only it is called a direct current. Direct current is written in short form as D.C ( or d.c.) the current which we get from a cell or a battery is direct current because it always flows in the same direction. The positive and negative polarity of a direct current is fixed. some of the source of direct current are dry cell, dry battery , DC generator , solar panel. Alternating current :  If the current reverses direction after equal interval of time it is called alternating current. Alternating current is written in short form as AC most of the power station in India generate alternating current the alternating current produce in India rivers its direction every one by 100 second. The positive and negative polarity of an alternating current is not fixed. Some of the source which produce alternating current are power house generators , car alternators and bicycle ...

Oersted Experiment showed that A current carrying wire exerts a mechanical force on a magnet , and if the magnet is free to move , this force can produce a motion in the magnet. The reverse of this is also true , that "A magnet exerts a mechanical force on a current- carrying wire , and if the wire is free to move , this force can produce a motion in the wire". Or  When a current-carrying conductor is placed in a magnetic field , a mechanical force is exerted on the conductor, which causes the conductor to move.This is known as motor Principle. Which forms the basis of working of electrical devices like electric motor , moving coil galvanometer. Reason: When a current is passed through the wire , it is pushed upwards , away from the magnet. It happens due to repulsion between the two magnetic fields : one from the magnet and one from current. Newton's third law of motion according to which if a current - carrying wire exerts a force on a magnet , then the magnet will exer...

 Object : To establish the relation between the loss in weight of a solid fully immersed in (i) Tap water (ii) Strongly salty water , with the weight of water displaced by it by taking two different solid. Apparatus : Spring balance , steel or brass Bob , graduated measuring cylinder , thread , water , clamp stand and a Eureka can ( a glass or metallic container with a spout. Theory : Archimede's principle states that when an object is immersed wholly or partially in a liquid , it experiences an upward force which is equal to the weight of the liquid displaced by it. Apparent loss of weight of solid in water = weight of water displaced by the solid. Diagram :  Observation :  Weight of the bob ( made of steel or brass ) in air , W1 = ........ gmt. Weight of the bob when dipped in water , W2 = ....... gwt Apparent loss of weight of bob in water = W1 - W2 = ...... gwt Density of water at 4°C ( From tables ) = 1 g/cm3 Volume of water collected in the measuring cylinder , V = ...

Experiment : To determine the density of solid ( Denser than water ) by using a spring balance and a measuring cylinder. Apparatus : Metallic block or a cylinder , fine cotton thread , a spring balance measuring cylinder , beaker , water and a clamp stand. In place of metallic cylinder , brass or steel Bob can also be taken. Theory : Density of a substance is defined as mass of a unit volume of the substance. Density = mass / Volume The SI unit of density is $kg/m^{3}$ Diagram : Observation :  Least count of spring balance = ........ g Mass of metallic cylinder using spring balance  (i) m1 = ........ g     (ii) m2 = ......... g Mean mass of the metallic cylinder= m1+m2 / 2 = ......... g Calculations :  Mean mass of the cylinder , m = .......g Mean volume of the cylinder , V = ...... $cm^{3}$ Hence , density of the solid = m/V = ..... $g/cm^{3}$ Result : The Density of solid = ....... $g/cm^{3}$ Precautions : 1. The metallic cylinder should be clean and dry....

Experiment : To determine the velocity of a pulse propagated through a stretched string / slinky. Object : To determine the velocity of a pulse propagated through a stretched string / Slinky. Apparatus: Heavy wooden block , a hook , slinky , chalk , metre scale and a stopwatch. Theory : Pulse is a sudden, non-Repetitive single disturbance of a short duration in the medium. In the formation of wave pulse , the medium vibrates for a short duration and then returns to its original undisturbed position. Observations : Distance from point A to B on table (S) = 1 m Total distance covered from point B to Point A and back (2S) = 1+1 = 2 m Calculations : Average time taken = t1+t2+t3/3 = .... sec Velocity of the pulse , v = 2S/t = 2/... =   m/s Result : The velocity of the pulse propagated through slinky = ..... m/s Precautions:  1. Sharp jerk should be given to the slinky for producing the pulse. 2. The slinky should be stout and flexible. 3. The distance should be measured accur...

Object : To verify the laws of Reflection of sound . Apparatus : Two metallic or cardboard tubes , stopwatch, Drawing board , plastic screen , protractor , chalk piece and a pencil. Theory : When sound is incident on wood , brick or a plaster wall , it returns back. The returning back of sound after striking a hard surface is called reflection of sound. Sound waves obey the laws of Reflection which are as follows :  1. The angle of incidence is equal to the angle of reflection. 2. Incident wave , reflected wave and the normal lie in the same plane. Diagram :  Observations :  Result : 1. Angle of incident sound wave = Angle of reflected sound wave. 2. Sound wave , normal and the reflected sound all lie in same plane. Precautions:   1. Careful measurement of angle should be done by using protractor. 2. Table top should be horizontal and the wooden board should be vertically placed. 3. The stopwatch should be placed near the end of tube placed on the left-hand side. 4...

The solenoid is a long coil containing a large number of close turns of insulated copper wire. The magnetic field produced by a current carrying solenoid is similar to the magnetic field produced by a bar magnet. Magnetic Field due to a Solenoid The magnetic field line inside the solenoid are in the form of parallel straight line. This indicate that the strength of magnetic field is the same at the all the point inside the solenoid. The strength of magnetic field is the same at all the point inside the solenoid. The magnetic field is uniform inside a current carrying solenoid. If a current carrying solenoid is suspendedly freely it will come to rest pointing in the north and south direction just like a freely suspended bar magnet. The end of solenoid which will be repelled by north pole of bar magnet will be its North pole and the end of solenoid which will be attracted by the north pole apar magnet will be its south pole. The strength of magnetic field produced by current carrying sol...

When a strong electric current is passed through the coil by closing the key the cardboard is gently taped we find that the iron filing arrange themselves in a definite pattern representing the magnetic line of force produced by the current carrying coil. The magnetic field lines are circular near the current carrying loop as we move away the concentric circles representing magnetic field lines become bigger and bigger at the centre of the circular loop the magnetic field lines are Straight. Direction of magnetic field is determined by applying the right hand thumb rule to each section of the coil. We find that the concentric line of force pass through the coil in the same direction. The strength of magnetic field produced by a circular coil carrying current is  (i) By increasing the number of turns of wire in the coil. (ii) By increasing the current flowing through the coil. (iii) By decreasing the radius of the coil. B = N u I/2r Clock Face Rule : A current carrying circular wire...

Magnetic Field Patterns Produced by Current carrying conductor having Different shapes :  1. Magnetic Field Patterns due to Straight current - carrying conductor :  The magnetic field lines around a state conductor carrying current are concentric circles who centres lie on the wire. When current is passed through wire ab it produce a magnetic field around it this magnetic field has a magnetic field lines around the wire ab the iron filling get magnetize and on taping the cardboard sheet the iron filling arrange themselves in circles around the wire showing that the magnetic field lines are circular in nature When current in the wire flow in the upward direction then the lines of magnetic fields are in the anticlockwise direction if the direction of the current in the wire is rivers the direction of magnetic field lines also get reversed. (i) Magnitude of magnetic field produced by a straight current - carrying conductor : B = u I/ 2πr The magnitude of the magnetic field produc...

Magnetic Effect of current ( Electromagnetism ) :  The magnetic effect of current was First discovered by Oersted in 1820 . Oersted found that a wire carrying a current was able to deflect a compass needle and concluded that a current flowing in a wire always gives rise to a magnetic field around it. Experiment to Demonstrate the magnetic effect of current:  When the Key is pressed and current is allowed to pass in the wire from A to B ( i.e from South to North then the North pole (N) of the needles is deflect towards the west. This shows that the current ( or the moving charge ) produces a magnetic field.  When the direction of the current in the wire is reversed by reversing the terminal of the battery , the North pole of the compass needle is deflected towards the East. 

Magnetic field :  The space surrounding a magnet in which magnetic force is exerted , is called a magnetic field. Magnetic field has both , magnitude as well as direction.  James Clerk Maxwell frst described the underlying unity of electricity and magnetsm in the 19th century. Like poles repel each other and unlike poles atract each other and Magnetc poles cannot be isolated. Compass : A compass is a device used to show magnetic field direction at a point. A compass is also known as a plotting compass.  A compass consists of a tiny pivoted magnet usually in the form of a pointer which can turn freely in the horizontal plane. The tiny magnet of the compass is also called 'Magnetic needle'. The tip of compass needle points towards the north direction whereas its tail points in the south direction. Magnetic field lines or Magnetic lines of force ) : A magnetic line of force is the line tangent to which at any point gives the direction of the magnetic field at that point. The...

What is Magnetism ? The property due to which a magnetic substance attracts other magnetic substances like iron pieces towards it , is called magnetism. The substance which possesses the property of magnetism is called a magnet. Type of magnets :  1. Permanent magnets : there are two types of permanent magnets : Natural magnets :  Definition: Pieces of naturally occurring substance like lodestone are called natural magnets. Properties : (i) Attractive property: They attract small iron pieces towards them. (ii) Directive property: when suspended freely , a magnets aligns itself in the geographical North - South direction for this reason , the suspended piece is called Lodestone or leading stone. Limitation:  (1) They may have irregular shape. (2) They generally have weak magnetic properties. Artificial magnets :  Artificial magnets are made of steel or special alloys like Alnico. These magnets have many small 'Atomic' magnets. Ordinarily the atomic magnets are oriente...

Scalar and Vector Quantities ? - Param Himalaya Physics What is a scalar Quantity ? It's example : A Physical quantity which is described completely by its magnitude or size is called a scalar quantity. Thus a scalar quantity has only magnitude and no direction. Example of scalar quantities :  Length , Distance , Area , Volume , Mass , Time , Power , Energy , Speed , temperature etc. Characteristics of scalar quantities : A scalar quantity can be represented by a number with proper units. The number represent the magnitude of the quantity. Example : 2 Kg. Here 2 is number and Kg is unit. The scalar quantities having similar units get added or subtracted by the usual rules of arithmetic. Example : 2m + 3m = 5m. What is a vector quantity? It's example A physical quantity which requires both magnitude ( or size ) and direction for its complete description is called a vector quantity. Thus , a vector quantity has both magnitude and direction. Example of Vector Quantities:  Dis...

In our daily life , the word "work" means any kind of mental and Physical activities , But in physics , the terms work has entirely a different meaning.  Scientific Conception of work :  Definition: Work is said to be done by a force on a body or an object of the force applied causes a displacement in the body or the object. Factors on which work done depends : (1). The magnitude of the applied force (F). W ∝ F (2). The distance travelled by the body on the application of force .  W ∝ S ( displacement) Work done by a contant force :  (i) When a contant force is applied in the horizontal direction. W = F.S (ii) When force is applied at an angle with the horizontal direction. W = FScosΘ # Dot product of two Vector quantities gives a scalar quantity. So work is a scalar quantity. Thus , Work done on a body by a force is defined as the product of the magnitude of the displacement and the force in the direction of the displacement of the body. Type of work done :  1....

AIM : To determine the focal length of a convex lens by obtaining the image of a distant object. APPARATUS : A Convex lens , optical bench , two needles , knitting needle , three uprights and a metre scale. THEORY : When an object  which placed between f and two f where f is the rough focal length of convex lens then its real inverted and magnified image is formed beyond to F on the other side of the lens as shown in figure the focal length of the convex lens can be calculated by the using the lens formula. 1/f = 1/v - 1/u , where u is the object distance and v is the distance of image from the lens. Observations:  Rough focal length of the convex lens , f = (i) ....... cm Actual length of the knitting needle , x =  Observed distance between the convex lens and object needle AB , y =  ....cm Observed distance between the convex lens and image needle A'B' , z =  ....cm Index correction for u , (x-y) =  ....cm Index correct...

The ability to see is called vision. It is also called eyesight. Sometimes the eye of a person cannot focus the image of an object on the retina properly. In such cases the vision of a person becomes blurred and he cannot see either the distant objects or nearby objects clearly and comfortably. The person is said to have a defect of vision. There four common defects of vision . 1. Myopia ( short-sightedness or near-sightedness ) : Symptoms :  Myopia is that defect of vision due to which a person cannot see the distant objects clearly.  The far point of an eye suffering from myopia is less than infinity. Reasons :  In a eye suffering from myopia , the cillilary muscles attached to the eye-lens donot relax sufficiently to make the eye-lens thinner to reduce its converging power. The image of a distant object is formed in front of the retina. Causes :  Due to high converging power of eye-lens ( because of its short focal length ) Due to elongated eye-ball being too long...

An eye can focus the images of the distant objects as well as the nearby objects on its retina by changing the focal length ( or converging power ) of its lens. The ability of human eyes lens to focus the distant objects as well as the nearby objects on the retina by changing the focal length ( or converging power ) of its lens is called accommodation. A normal eye has a power of Accommodation which enables objects as far as infinity and as close as 25 cm to be focused on the retina. Range of vision of a normal Human eye :  Far point : the farthest point from the eye at which an object can be seen clearly is known as the "far point" of the eye. The far point of the normal human eye is infinity Near point ( distinct vision ) : The minimum distance at which an object must be placed so that a normal eye may see it clearly without any strain is called the least distance of distinct vision. The least distance of distinct (clear) vision for a normal Human eye is about 25 centimetre...

Power of lens | Units | Combination in series and parallel - Param Himalaya  Power of a lens Power of a lens is a measure of the convergence or divergence. The power $P$ of a lens is defined as the tangent of the angle by which it converges or diverges a beam of light parallel to the principal axis falling at unit distance from the optical centre. $\tan \delta = \frac{h}{f}$  if h = 1 then  $\tan \delta = \frac{1}{f} \text{ or } \delta = \frac{1}{f}$ $\text{ for small } \delta.$ That is, $P = \frac{1}{f_{(\text{in m})}} \quad \dots (i)$ or, $P = \frac{100}{f_{(\text{in cm})}}$ As per lens maker's formula, the focal length of a lens is given by  $\frac{1}{f} = (n-1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)$ $\therefore$ Power of lens, $P = \frac{1}{f} = (n-1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right) \quad \dots (ii)$ Thus, power of a lens is more if its focal length is small and power of a lens is less if its focal length is large. SI unit of power : The SI un...

There are similar rules for constructive ray-diagrams for obtaining image with concave lenses. Rule 1. A ray of light which is parallel to the principal axis of a concave lens , appears to be coming from it's focus after Refraction through the lens. Rule 2. A ray of light passing through the optical centre of a concave lens goes straight after passing through the lens. Rule 3. A ray of light going towards the focus of a concave lens , becomes parallel to its principal axis after Refraction through the lens. Formation of image by a concave lens :  1. When an object is placed anywhere between optical centre (C) and infinity in front of a concave lens , the image formed is :  (i) Between optical centre (C) and focus (F). (ii) Virtual and Eract  (iii) Diminished ( Smaller than the object). 2. When an object is at Infinity from a concave lens , the image formed is :  (i) At focus (F). (ii) Virtual and Eract (iii) Highly diminished ( Much smaller than the object ).