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Wednesday, June 5, 2024

Ohm's law physics practical for ITI fitter & GSEB Std 8 & 12

Ohm's Law

Ohm's Law

AIM :-

A voltmeter, a current meter, and an unknown resistance etc. are given to you. Prepare an appropriate circuit to verify Ohm’s law. With appropriate values of current and voltages, only with the help of calculations, determine the value of unknown resistance.

PRINCIPLE

Potential difference in a conductor produces electric current.

APPARATUS :-

A unknown resistance,

a voltmeter (0 - 10 V),

a milliammeter (0 - 500mA), a battery,

a rheostat,

a tap key,

connecting wires.

PRECAUTIONS : -

All the connections must be tight.
Plastic or rubber should not be pressed below the connecting terminals.
When current does not flow in a circuit the pointer in both ammeter and voltmeter must be on zero. If it is not so then adjust the pointer on zero or consider the zero error.
Range of the meters must be appropriate.
Choose a proper scale while plotting the graph so that the graph is sufficiently large and it occupies most part of the graph-paper.

Ohm's Law apparatus

Ohm's law Line diagram

Ohm's law line diagram

Ohm's law practical

Ohm's law observation table

Ohm's law graph

For more details View Video.

Ohm's Law

Change in Chemical reactions Exothermic OR Endothermic GSEB Science 8 to 12

Exothermic reaction

To measure the change in chemical reactions and conclude whether the reaction is exothermic or endothermic.

AIM : To measure the change in chemical reactions and conclude whether the reaction is exothermic or endothermic.

THEORY : During the chemical reaction if the temperature increases the reaction is exothermic and if temperature decreases the reaction is endothermic.

APPARATUS : Conical flask, 250 ml Beaker, Stand, Thermometer, Glass rod, measuring cylinder, stirrer.

Exothermic Reaction (step 1)

Exothermic Reaction (step 2)

Exothermic Reaction (step 3)

MATERIAL : Dilute hydrochloric acid, Zinc metal, Solid ammonium chloride,

Observation

(1) initial temperature of dilute hydrochloric acid ⁰C.

(2) Temperature of the mixture when Zinc metal dissolves in hydrochloric acid = ⁰ C.

(3) Difference of temperature = ⁰C.

(4) Give chemical reaction of Zinc metal with hydrochloric acid.

NOTE : (1) Similarly heat of neutralization in neutralization reaction between dilute hydrochloric acid and sodium hydroxide can be measured.

(2) The increase in temperature can be noted when dissolution of solid sodium hydroxide in water is carried out.

PRACTICAL USES

The combustion reactions of kerosene, Petrol, LPG are exothermic, therefore these substance are used as fuel.

Endothermic Reaction :

Endothermic reaction (step 1)

Endothermic reaction (step 2)

Endothermic reaction (step 3)

Observation

(1) Initial temperature of water = ⁰C.

(2) Temperature o ammonium chloride solution when dissolved in water = ⁰ C.

(3) Difference between temperatures = ⁰C.

NOTE : * Similarly when Sodium nitrite is dissolved in water decrease in temperature occurs.

PRACTICAL USES

Some substances absorb heat from atmosphere, during the reaction therefore used to reduce the temperature.

. TO VERIFY THE LAWS OF REFLECTION USING A PLANE MIRROR GSEB Std 8 to 12 Science practical

Reflection of Plain mirror

Reflection of Plain mirror.

Aim : To verify the laws of reflection using a plane mirror.

Principle : When a ray of light is incident on a reflecting surface, it changes its direction of motion and travels in the original medium following certain laws. This phenomenon is called reflection of light.

Apparatus : Drawing board, a drawing paper (White), a plane mirror, a foot-rule, a pencil, four pins, four push pins, a protactor, a stand for the plane mirror.

Reflection of Plain mirror Practical

Reflection of Plain mirror

Ø First of all fix the white drawing paper on the drawing board using push pins.

Ø First of all fix the white drawing paper on the drawing board using push pins. Place the plane mirror along with its stand and fix its position AB.

Ø Now draw a line PQ which passes through the mid-point ‘P’ of AB and perpendicular to AB.

Ø PQ is called the normal to AB.

Ø Draw a ray RP which makes some angle with the normal (PQ).

Ø Draw a ray RP which makes some angle with the normal (PQ). On the ray RP fix two pins P₁ and P₂ vertically with 2-3 cm separation between them. Ray RP is incident ray.

Ø Now from the other side of PQ , (in which incident ray is not there) see the images of pins P₁ and P₂ fix other two pins P₃ and P₄ vertically so that pins P₃, P₄ and images P₁ and P₂ appears collinear at their lower ends.

Ø Now remove the pins and the mirror. Join the marks of P₃ andP₄ and obtain the reflected ray PS.

Ø Repeat the experiment for different angles of incidence. Measure angle of incidence and angle of reflection. Note your reading in the observations table.

Reflection of Plain mirror

Reflection of Plain mirror Observation table

Conclusion :

Practical uses : We can study the laws of reflection. We can also study the images obtained by the plane mirror. We can come to know how reflection is used in various optical appliances, e.g., periscope, keleidoscope.

For more details view Video.

Reflection of Plain mirror.

focal length of a concave mirror by obtaining an image of a far distance object, GBSE for std 8 to 10 science practical

Focal length of a concave mirror

Focal length

To determine the focal length of a concave mirror by obtaining an image of a far distance object

AIM :- To determine the focal length of a concave mirror by obtaining an image of a far distance object.

APPARATUS :- A concave mirror of diameter approximately 10 cm., stand, screen, foot-rule, etc.

PRINCIPLE :- Rays coming from a far distance object are almost parallel. Such rays, parallel to the principal axis, after being reflected by a concave mirror, are focused at the principal focus of the mirror. Distance between the principal focus and the pole of the mirror is known as the focal length.

NOTE : Here screen should be taken small, so that rays coming from the object are not blocked by the screen itself. Diameter of the screen here can be approximately 3 – 4 cm.

Focal length of Concave mirror

Focal length of Concave mirror,

Focal length of concave mirror Adjustment

Focal Length of Concave mirror

OBSERVATION

Distance between the pole of the mirror and the image on the

screen = focal-length = CM.

CONCLUSION

PRACTICAL USES

Concave mirrors are used in head lights of vehicles, solar furnace, solar cooker, shaving mrror, etc. For all such applcatons it is necessary to know the focal length of the mirror to used. It can be estimated using the given method.

For more details view Video.

Focal length

Draw the path of through glass slab and, hence, to measure the angle of incidence and the angle of image.science practical std 8 to 10

Rays passing through Glass slab

Rays passing through Glass slab

To draw the path of a ray passing through a glass slab and, hence, to measure the angle of incidence and the angle of image.

AIM : To draw the path of a ray passing through a glass slab and, hence, to measure the angle of incidence and the angle of image.

PRINCIPLE: When an oblique ray of light enters from one transparent medium to another transparent medium, at the surface separating these two media, the light ray changes its path. This phenomenon is called refraction of light. When a ray of light passes through a glass-slab, it is refracted twice, as a result of which, the emergent ray becomes parallel to the incident ray.

APPARATUS : Glass –slab, Drawing-board, Drawing paper (White), Foot-rule, Pencil, Pins, Push pins and Protractor.

PROCEDURE :-

Ø Fix a white drawing-paper on the drawing board using push pins. Now place the glass-slab on it and mark its position PQRS by drawing its out-line using a pencil.

Ø Now draw a ray AB such that it is not perpendicular to PQ. Fix two pins upright with separation of 2-3 cm on this ray.

Ø Now try to see the images of P₁ and P₂ from side RS and fix pins P₃ and P₄ upright so that images of P₁ and P₂ and pins P₃ and P₄ become collinear at their lower ends.

Ø Now remove the slab and the pins obtain emergent ray CD by drawing a line passing through marks of P₃ and P₄, which intersects RS at C.

Ø Join B and C to complete the path of the ray. Now draw a normal MN to the surface PQ in such a way that it passes through B. Also draw M’N’, through C to the surface RS.

Ø Measure ÐAMB (Angle of Incidence) and ÐOCN’ (Angle of Emergence).

Ø Repeat the experiment for various values of angle of incidence AMB and note your observations in the table.

Glass Slab for Practical

Rays passing through Glass slab

Rays passing through Glass slab Observation table

CONCLUSION :

PRACTICAL USES :

We can study the path of a ray when it passes through a glass slab. Here emergent ray and incident ray are parallel, but there is some distance between them. This distance depends on angle of incidence, breadth of the slab, and type of material used in the slab. i.e. refractive index of the material. From these information we can have an idea of the refractive index of the material used.

For more details view Video.

Rays passing through Glass slab.