Find resistance of two resistors series and parallel, std 8 to 12 GSEB

Effective resistance of two resistor practical

To find effective resistance of two resistors connected in (1) Series (2) Parallel connection.

(ohm’s Law)

AIM : To find effective resistance of two resistors connected in (1) Series (2) Parallel connection.

PRINCIPLE  :  When two resistors are connected in series effective resistance is equal to the sum of their resistance. When two resistors are connected in parallel connection reciprocal of effective resistance is equal to the sum of reciprocal of the resistance.

APPARATUS  :   Ammeter ( 0 – 500 mA), Voltmeter ( 0 -10 V ),  Battery eliminator ( 0 – 12 V), Two unknown  resistors, Plug-key, rheostat, wires,

Find Resistance of Resistor Practical

Find Resistance of Resistor Practical

SERIES CONNECTION

Find Resistance of Resistor Practical

PARALLEL CONNECTION

Find Resistance of Resistor Practical

Observation table of Resistor practical

CONCLUSION

(1) Average value of resistance  R₁ =             W          

(2) Average value of resistance  R₂ =         W

(3) Average value of effective resistance in series connection R₃ =     W

(4) Average value of effective resistance in parallel connection R₄ =     W        

Note : Verify :    (1) R₃ = R₁ + R₂ for series connection.

                               (2) 1/ R₄ = 1/ R₁ + 1/R₂ for parallel connection

PRACTICAL USES

Many times resistance are connected in series e.g. series of small bulbs used for decoration. Domestic connections are always in parallel, e.g. bulbs, tube-light, t.v., fridge. Etc.

Determine focal length of Convex lens of a far distance object std 8 to 12 GBSE.

Focal length of Convex lens

To determine the focal length of a convex lens by obtaining an image of a far distance object. 

AIM  : To determine the focal length of a convex lens by obtaining an  image of a far distance object.

PRINCIPLE   :  Rays parallel to the axis, after being refracted by a convex lens, are focused on the principal focus. Distance between the optical centre and the principal focus is known as the focal length.

APPARATUS   :   Convex lens, Stand, Screen, Foot-rule, Paper, Pencil,

Convex lens to find Focal lens

Observation

Conclusion

Practical uses

Convex lens of proper focal length are usedin optical instruments like simple microscope, compound microscope, telescope, etc,. Also the method given here in the simplest way to estimate the focal length of a convex lens.

TANGENT GALVANOMETER, Physics practical std 11 & 12 GSEB

Tangent Galvanometer

TANGENT GALVANOMETER, 

AIM :

To determine the value of H with the help of a tangent galvanometer.

APPARATUS :

A tangent galvanometer, an ammeter, a battery, a simple key, a rheostat, a reversible key and a spirit level.

PRECAUTIONS

1)      Keep the tangent galvanometer away from an ammeter.

2)       The circular platform must be properly leveled horizontally.

3)       Before taking the reading of the pointer of a tangent galvanometer, the sight should be so adjusted that the pointer and its image in the mirror, become collinear.

4)       The rheostat should be so adjusted that the deflection is between 30⁰ and 60⁰.

5)       The coil of the tangent galvanometer should be adjusted parallel to the magnetic field of the earth.

Apparatus for Tangent Galvanometer Practical

Line Digram for Tangent Galvanometer

Insert Key.

Tangent Galvanometer Procedure

Connect reversible key and adjust rheostat.

Note down reading of Tangent Galvanometer, and ammeter.

Tangent Galvanometer Procedure

Connect  key in reverse position and adjust rheostat.

COMPARISION OF EMF , principle of potentiometer GSEB std 11 & 12 Physics practical

Comparision of emf

COMPARISION OF EMF 

Experiment  6(a)

AIM :-

Two cells EA and EB, a potentiometer and necessary components are given. Connect E_A and E_B one after the other and find the ratio of their emfs.

PRINCIPLE :

It works on the principle of potentiometer.

APPARATUS:

A resistive wire, Laclanche cell, Daniel cell, a main battery, two rheostats, Potentiometer, jokey, key, Galvanometer, Resistance box,

Apparatus for comparision of EMF

Adjust all apparatus as per shown here

Line Diagram fof Comparision of EMF

Line Diagram fof Comparision of EMF

Comparison of EMF Practical

Comparison of EMF Practica

Comparison of EMF Practica

Comparison of EMF Practical Procedure

Calculation table for Comparison of EMF

Experiment  6(b)

AIM :-

Verify the results by joining both the cells in helping and opposing conditions.

APPARATUS :

A resistive wire ( ~ 400  cm length of uniform cross-section fixed on a wooden board, two primary cells ( e.g. Laclanche cell and Daniel cell ), a main battery ( 0 – 12 V ) ( the voltage of this battery must be more than E_A + E_B), two rheostats Rh₁(o - 25W) and Rh₂ ( 0 - 500W)

Apparatus of Comparision of EMF (ii)

PRECAUTIONS

1    First decide from experiment :6(a), which cell has larger emf. Call that cell E_A and the other cell E_B

2      Here, Rh₁ should be having smaller resistance than Rh₂.

3      The value of Rh₁ should be the same while taking observations for EA and E_B.

            For the observation of each set of helping-opposing conditions, the resistance in Rh₁ should not be changed.

Line diagram Comparision of EMF (Helping Connection)

Comparision of EMF Practical

Comparision of EMF Practical

Comparision of EMF Practical

Result :

1  By connecting E_A and E_B separately :  E_A / E_B = ……………

2   By connecting E_A and E_B in helping and opposing conditions : EA / EB = ……..

To prepare Soap by cold process. Science practical GSEB for std 8 to 12.

Soap making practical 

Soap making with Cold Process.

AIM :  To prepare soap by cold process.

THEORY  :  Sodium hydroxide and vegetable oil reacts to give soap and the process is called saponification.

APPARATUS :  Beaker, glass-rod, bunsen burner, mould, wire gauze, Sodium hydroxide, vegetable oil, Soap, Sodium hydroxide, vegetable oil, Salt,

CHEMICALS : Sodium hydroxide, vegetable oil (castor oil) and salt.

Soap making with cold process

Soap making with cold process

Soap making with cold process

Soap making with cold process

Soap making with cold process

Observation :

Conclusion :

Uses : Soap is used to remove dirt from the surface of clothes.

For more details view Video :

Soap making with Cold Process.

Cleaning capacity of soap in soft & hard water, Science practical GSEB for std 8 to 12.

Soap cleaning on hard and soft water

Soap Cleaning capacity

AIM :  To study the cleaning capacity of a sample of soap in soft water and hard water..

THEORY :  Hard water  contains salts of Ca and Mg that affects the cleaning capacity of soap. Hard water consumes  more soap.

APPARATUS :  250 ml glass beaker, glass rod, white cloth (two pieces of 7 cm * 7 cm), Hard water, Salts, Calcium Chloride, Magnesium chloride, Washing Soap, water soluble ink,

MATERIALS : Standard washing soap, distilled water, water soluble ink, calcium chloride or magnesium chloride.

Soap cleaning capacity Practical

Soap cleaning capacity Practical

Soap cleaning capacity Practical

Soap cleaning capacity Practical

Soap cleaning capacity Practical

Observation

( i)  Type of water in beaker no (1) :

( ii)  Type of water in beaker no (2) :

( iii)  From white cloth in which beaker ink-blot is removed (1) or (2) ?

Conclusion :

Uses :

Soft water give rich lather with soap, therefore its cleansing capacity is more than hard water. No more soap is wasted in soft water.

Foaming capacity of samples of soap, Science GSEB for std 8 to 12

Soap foaming capacity practical

AIM :    To compare the foaming capacity of three samples of soap.

THEORY :   On boiling vegetable oil or fats with caustic soda solution, sodium salt of fatty acids is obtained which is known as soap. Foaming capacity of different soaps are different from each other.

APPARATUS    :  Three big test tubes, measuring cylinder, stop watch, test tube stand, Vegetable oil, Caustic Soda, Sodium Salt, Fatty acid, Soaps, Distilled water.

CHEMICALS    : Three different types of sample of soap and distilled water.

Soap foaming capacity practical 

Soap foaming capacity

Observation

( i)  The time in which the foam just disappears in test tube (1) :      minute.

( ii)  The time in which the foam just disappears in test tube(2) :      minute.

( iii) The time in which the foam just disappears in test tube(3):       minute.

Conclusion  :

Uses : The foaming is less in the hard water. The foaming capacity of detergent is more than the foaming capacity of soap.

Physical and chemical properties of acetic acid. Science GSEB std 8 to 12.

Acetic acid Physical and Chemical properties

AIM : To study the physical and chemical properties of acetic  acid.

THEORY :  Acetic acid in an organic acid. It contains carboxylic acid group – COOH. Its chemical reactions are the characteristics of COOH group.

APPARATUS  :  Three to four test tubes, test tube stand. Acetic Acid, Organic acid, Carbozylic acid, Zinc metal, Vinegar, Sodium Bicarbonate solution, Blue Litmus Paper,

CHEMICALS    :  Acetic acid, Zinc metal sodium bicarbonate solution and red blue litmus papers.

Acetic acid Properties

Acetic acid Properties

Acetic acid Properties

Acetic acid Properties

Acetic acid Properties procedure

Acetic acid Properties practical 

Conclusion :

Uses :  4-6 % solution of acetic acid is called vinegar. It is used for making the food tasty and sour and also used as food preservative.

EFFECT OF TEMPERATURE ON RESISTANCE, GSEB Physics practical std 8 to 12

Effect of Temperature on Resistance

EFFECT OF TEMPERATURE ON RESISTANCE

AIM :-

You are given a Wheatstone bridge, a container filled with a liquid, a resistor made from an iron wire etc. Immerse the resistor in liquid and connect it in an appropriate arm of Wheatstone bridge. Measure the resistance at different temperatures. Draw the graph of resistance versus temperature and from it find the resistance at 20⁰ c and 100⁰c. Use the following formula to determine(a ), the temperature coefficient of resistance.

Formula to calculate Effect of temperature on Resistance

PRINCIPLE  :-  On increasing the temperature of a conductor its resistance increases.

APPARATUS :- A coil of iron wire, container filled with liquid, a battery (2 V), a rheostat, a sensitive galvanometer, a simple key, a thermometer, a calorimeter, a burner, wire gauge, resistance box. 

Apparatus for Effect of Temperature on Resistance 

Practical Effect of Temperature on Resistance 

Procedure of Effect of Temperature on Resistance 

PRECAUTION :-               

(1)    Keep the iron cylinder completely immersed in liquid.

(2)    Keep all connections tight.

(3)    Stir the calorimeter for uniform heating of water. Note the temperature of the liquid immediately after the null point is obtained at every observations.

Graph of Effect of Temperature on Resistance

Draw the graph of R_t ® t. it is a linear graph. Extend this straight line on both the sides. Find R₂₀ and R₁₀₀ at the temperatures 20 ⁰C and 100 ⁰C respectively.

R₂₀  = …………… W at temperature 20 ⁰C

R₁₀₀ = …………… W at temperature 100 ⁰C

\     The temperature co-efficient of resistance of the given iron-wire is

RESULT :-  Temperature coefficient of resistance at given iron wire a = ………( ⁰c) ^-1