PARTICULARS

Name:

Class: XII A

Exam No:

Academic Year: 2017 – 2018

School: Sunrise English Private School

Name of Teacher: Mrs.Swapna

Signature:

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ACKNOWLEDGEMENT

First of all I would like to express my sense of gratitude to the school Principal Dr.Thakur S. Mulchandani and the Vice Principal Mrs.Sheela John for giving me an opportunity to attend this project.

Then I would like to express my earnest appreciation to the Physics teacher Mrs.Swapna and the lab assistant Mrs.Usha for their proper guidance which lead to the successful completion of this project.

Last but not the least I would like to thank my parents for providing

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me with the required sources for the accomplishment of this project.

CONTENTS

1. Assembling an Electrical Circuit

2. Potential Gradient – Potentiometer

3. Glass Slab

4. Image Formation – Convex Lens and Concave Mirror

5. Identification of Circuit Elements and Measurement of Resistance from colour coded Carbon Resistors

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ACTIVITY 1

ASSEMBLING AN ELECTRICAL CIRCUIT

AIM:

To assemble an electrical circuit to measure the EMF and terminal voltage of a cell.

APPARATUS REQUIRED:

Voltmeter , battery , one way key , ammeter , resistance box ,connecting wires.

THEORY:

EMF –it is the potential difference when the cell is not is not in use.

Terminal Voltage-The potential difference between the terminals of the circuit when the current is drawn is drawn from it.

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V = E – IR , where l – Current

R – internal resistance

CIRCUIT DIAGRAM:

E – BatteryA – AmmeterR – ResistorRh – RheostatV – VoltmeterK – Key

MODEL GRAPH:

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PROCEDURE:

1. Connect the components as given in circuit diagram.

2. Measure emf of cell using voltmeter in open circuit mode.

3. Introduce resistance of 2 in the resistance box .Close the circuit and measure the voltage across the cell.

4. Repeat the experiment with different values of R as 5Ω , 10 Ω , 15 Ω , 100 Ω, 200 Ω , 500 Ω etc.…. and note the corresponding terminal voltage.

5. Plot a graph between R and V as given in the model graph.

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OBSERVATION:

Least Count of Voltmeter: 0.1 V

Range of Voltmeter : 0-3 V

S. No.

EMF of cell E, (volt)

External resistance

(R)

Terminal Voltage

1.

2.

3.

4.

5.

6.

7.

8.

7

9.

10.

GRAPH:

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RESULT:

1. A circuit has been assembled using given components.

2. As the external resistance is increased, it is observed that emf of the cell remains constant but terminal voltage of cell increases.

SOURCES OF ERROR:

1. The EMF of battery may not be constant.

2. The connecting wires may not have negligible resistance.

PRECAUTIONS:9

1. Use voltmeter, Ammeter, and Rheostat of suitable range.

2. All connections must be right.

ACTIVITY 2

POTENTIAL GRADIENT – POTENTIOMETER

AIM:

To find the variation in the potential drop with length of potentiometer wire and to find potential gradient.

APPARATUS REQUIRED:

Potentiometer, battery, key, rheostat, voltmeter, jockey and connecting wires.

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THEORY:

When the two ends of the wire are kept at different potentials, a current flows along the wire. This current causes fall in potential along the length of the wire. Potential Gradient (V/L) is a constant for a wire of uniform area of cross-section.

CIRCUIT DIAGRAM:

MODEL GRAPH:

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Slope = Voltmeter Reading / Length

PROCEDURE:

1. Connect the battery to the ends A and B of the potentiometer wire through a rheostat and one way key K. Take care that the positive terminal of the battery should be connected to terminal A.

2. Connect the voltmeter with its positive terminal to A and connect a jockey J at the negative terminal.

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3. Plug the key in Km touch the jockey J near the end B and adjust the rheostat Rh so that the voltmeter reads the voltmeter value.

4. Divide the total length of the wire into 10 parts. Touch the jockey K at the first part say 50 cm and record the voltmeter reading in tabular column. Take care that the current remains steady in the ammeter A.

5. Repeat step (4) nine times, every time by lifting jockey J and touching 100 cm ahead, i.e., note the reading of potential drop at 150 cm, 250 cm, 350 cm, 450 cm and so on up to 950 cm length of mark of the wire of the potentiometer.

OBSERVATIONS:

Least count of Voltmeter: 0.5 V

Range of Voltmeter: 0 – 3

S. No.

Length (cm)

Voltmeter Reading (V)

K = V / I (V/cm)

13

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.GRAPH:

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RESULT:

1. The graph between potential drop and length of potentiometer wire is a straight line.

2. The potential gradient by calculation: 15

3. From graph, it is observed that the potential drop per cm of the potentiometer wire is:

PRECAUTIONS:

1. The connection should be neat and tight.

2. Voltmeter should be of proper range.

SOURCES OF ERROR:

1. Rheostat may have high resistance.

2. EMF of cell may not be constant.

ACTIVITY 3

GLASS SLAB16

AIM:

To observe refraction and lateral deviation of a beam of light incident obliquely on a glass slab.

APPARATUS REQUIRED:

A rectangular glass slab, a sheet of white paper, fixing pins, drawing pins, meter scale, protractor and pencil.

THEORY:

When a ray of light incident obliquely on a rectangular glass slab, it suffers refraction through the glass medium and emerges from the glass slab in the same direction of the incident ray. It suffers lateral displacement (d), proportional to thickness (t) of glass slab.

Displacement is given by : d = t sec or sin (i-r)

DIAGRAM:17

OBSERVATION:

S.No.

Thickness of slab (cm)

Lateral

Shift (cm)

<i <e

<r n = Sin i / Sin r

1.

2.

3.

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PROCEDURE:

1. Fix a sheet of white paper on the drawing board with the help of fixing pins.

2. Keep the glass slab at the central position of the paper and mark its boundary AB with a sharp pencil.

3. Remove the slab from the sheet and draw a straight line PQ obliquely with the help of a scale and keep the glass slab on its drawn boundary.

4. Fix two drawing pins on the line PQ had drawn obliquely at distances 6 cm between themselves.

5. See the images of these pins through the lower surface CD of the glass slab.

6. Fix two more drawing pins at distances of 6 cm between them such that these two pins cover the images of first two pins at the upper surface of the glass slab. Take care that there should not be any parallax between the object pins and

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image pins, i.e., all four pins will appear to lie along a straight line when seen through the lower surface CD of the glass slab.

7. Mark the position of the image pins by using a pencil on the lower surface CD of the glass slab.

8. Join the points Q and R.

9. Produce PQ forward to cut DC at T and draw TU perpendicular to RS.

10. Measure the perpendicular distance TU that will give the lateral displacement.

11. Repeat the experiment by placing the slab of greater thickness. You will observe that the lateral displacement (t) is directly proportional to the thickness (d) of the glass slab.

RESULT:

1. The emergent ray is parallel to the incident light and it is laterally displaced.

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2. The lateral displacement of the emergent ray increases with the increase in thickness of the glass slab.

3. The ratio sin i/sin r = constant. This constant is called refractive index of material of slab.

ACTIVITY 4

CONVEX LENS AND CONCAVE MIRROR – IMAGE FORMATION

AIM:

To study nature and size of image formed by a convex lens on a screen using a candle and screen for different distances of candles from the lens.

To study the size of image formed by a concave mirror using candle and screen for different distances of candle from the mirror.

APPARATUS REQUIRED:

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Convex lens, lens holder, candle, screen, meter scale, etc…

Concave mirror, mirror holder, screen, candle, meter scale..

THEORY:

According to the lens equation

1/f = 1/v – 1/u or f = (uv) / (u – v)

According to mirror formula

1/f = 1/u + 1/v or f = (uv) / (u + v)

Where,

u – Object distance v – Image distance f – Focal length

RAY DIAGRAMS: FOR CONVEX LENS22

a) Object at Infinity

b) Object beyond 2F

c) Object at 2F

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d) Object between F and 2F

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e) Object at F

f) Object between F and O

RAY DIAGRAMS FOR CONCAVE MIRROR:

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a) Object at Infinity

b) Object beyond

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c) Object at C

d) Object between F and C

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e) Object at F

f) Object within F

PROCEDURE FOR CONVEX LENS:28

1. Find the approximate focal length of the lens by obtaining a sharp and clear image of the distant object on a white paper.

2. Level the optical bench by using a spirit level.

3. Mount the convex lens in its holder and keep it on the central upright of the optical bench.

4. Mount the screen on the screen on the right hand side upright and the burning candle on another upright on the left of the lens.

5. Keep the candle upright at F on the optical bench. Try to locate the real inverted image on the screen by moving gradually away from the lens.

6. Now shift the candle position between F and 2F on the optical bench. Move the screen to the position beyond 2F.

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7. Now shift the candle to the position at 2F. Obtain the sharpest image by moving farthest from the lens.

8. Shift the candle towards beyond 2F and locate the sharpest image.

9. Move the candle beyond 2F and obtain a sharp image.

PROCEDURE FOR CONCAVE MIRROR:

1. Find the approximate focal length of the given concave mirror by obtaining a sharp and clear image of a distant object on a white paper.

2. Lift the optical bench. Keep the mirror on the clamp on one of the three uprights on the bench and keep one near one end of the optical bench.

3. Look into the mirror keeping your eye at the height of the pole or vertex of mirror.

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4. Mount the lighted candle and the screen on the other two uprights and adjust their heights in such a manner that the top of the candle flame, the centre of the white screen, i.e., the upper edge AB of the slot in the screen and the pole of the mirror lay at the same height.

5. Now adjust the upright carrying the candle literally perpendicular to the scale such that the line joining the pole of the mirror and tip of the candle flame is parallel to the length of the bench.

6. Find out the approximate position of the centre of curvature using the relation

R = 2F

7. The approximate value of the focal length has already been determined.

8. The centre of curvature c lies at a distance R from the pole of the mirror.

9. Displace the candle upright towards the pole of the mirror so that it lies between the focus f and centre of curvature c of the mirror.

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10. Locate the position of the image of the candle flame on the principal axis of the mirror. Adjust the position of the screen by shifting it along the bench such that the sharper image of the candle flame is obtained on it. Since, the candle lies between c and f, you see a real inverted and magnified image beyond c.

OBSERVATIONS FOR CONVEX LENS:32

S.No.

Position of

Object

Position of

Image Forme

d

Nature of

Image Forme

d

Size of the

Image

1. At Infinity

At F Real and

Inverted

Point sized or Highly

Diminished

2. Beyond 2F

Between F and

2F

Real and

Inverted

Smaller than

object

3. At 2F At 2F Real and

Inverted

Same size as

the object

4. Between F and

2F

Beyond 2F

Real and

Inverted

Larger than

object

5. At F At Infinity

Real and

Inverte

Infinitely large

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d6. Between f

andOn the

same side of the lens as

the object

Virtual and

erect

Larger than

object

OBSERVATIONS FOR CONCAVE MIRROR:

S.No.

Position Of Position of Image (cm) Magnifi

ed Or diminish

edObject

ImageReal or

Virtual

Erect or

Inverted

1. At Infinity

At F Real Inverted

Point Image or diminish

ed2. Beyon

d CBetween F

and C

Real Inverted

Diminished

3. At C At C Real Inverted

Same size

4. Betwe Beyon Real Inverte Magnifie34

en F and C

d C d d

5. At F At Infinity

Real Inverted

Highly Magnifie

d6. Within

FBehind

the mirror

Virtual

Erect Magnified

RESULT

CONVEX LENS:

1. As the object is moved from infinity to optic centre of convex lens, size of image gradually increases.

2. When the object is beyond 2F, the image is smaller in size than the object.

3. When the object is at 2F, the image is smaller in size than the object.

4. When the object is moved to a position between F and 2F, the size of the image becomes larger than the size of the object.

CONCAVE MIRROR:

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1. The size of the image gradually increases as the object is moved towards the concave mirror.

2. When the object is beyond c the image is smaller in size. And formed in between f and c.

3. When the object is at c the image is also formed at c and the image size becomes equal to the object.

4. When the object is moved to position c and f the size of the image becomes larger and forward beyond c.

5. When the object is moved to position within f the size of the image is highly magnified and formed behind the mirror.

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ACTIVITY 5

IDENTIFICATION OF CIRCUIT ELEMENTS AND

MEASUREMENT OF RESISTANCE

AIM:

To identify circuit elements such as diode, LED, transistor, capacitor and IC from a mixed collection of such items and measurement of resistance.

APPARATUS REQUIRED:

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Battery eliminator, reversing key and mixed collection of circuit elements.

THEORY:

For identification, appearance and working of each item has to be considered.

Diode: A diode is a two terminal device. It conducts when forward biased. It does not emit light while conducting.

Light emitting diode (LED): An LED is also a two terminal device. It conducts when forward biased and does not conduct when reverse biased. It emits light while conducting.

Transistor: A transistor is a three terminal device. These terminals represent emitter (E), base (B) and collector (C).

Integrated Circuit (IC): An IC is a multi – terminal device in the form of a chip.

Resistor: A resistor is a two terminal device. It conducts when operated with AC as well as DC voltages.

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Capacitor: A capacitor is a two terminal device. It does not conduct with DC voltage.

CIRCUIT DIAGRAM:

E – BatteryRh – RheostatMa – Multiammeter, K – Reversing KeyPROCEDURE:

1. Check the physical appearance of the component.

2. If it has four or more terminals and has the appearance of a chip, i.e., black rectangular block then it is an AC.

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3. If it has three terminals; the component in all probability is a transistor. To confirm, set up the multimeter in resistance mode.

4. Connect the black terminal or common terminal of the multimeter to one of the extreme legs of the component and the second red terminal or positive terminal of the multimeter to the central leg of the component. Check the multimeter deflection. f the deflection is observed, interchange the multimeter terminals. If no deflection is observed, the component is a transistor. Repeat this test by connecting the multimeter terminals to the central leg of the transistor; if similar behavior is observed, the component is a transistor.

5. If the component has two terminals, it could be a resistor, a capacitor, a diode or LED.

6. Look for colour bands, if it has a typical set of three colour bands followed by a silver or gold band, the component is a resistor.

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7. Connect the multimeter terminals to the component terminals and watch for multimeter deflection keeping the multimeter knob in resistance mode.

8. If the multimeter shows a deflection, the component could be a resistor, a diode or LED.

9. If the deflection is accompanied with an emission of light, the component is a LED.

10. If no light is emitted then interchange the multimeter terminals connected to the component.

11. If the component still gives deflection in a multimeter, then the component is a resistor.

12. If the pointer of the multimeter show deflection when its terminals are connected across the component in one direction and does not show deflection when the terminal, of the multimeter in

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opposite direction and also there is no emission of light, then the component is a diode.

13. If the multimeter does not show any deflection on connecting its terminals either way to component, then it is a capacitor.

OBSERVATION:

S.No.

Device No. of legs

Direction of current

Symbol

1. Resistor 2 The conduction in both the sides i.e.,

Bi - Directional2. pn

junction diode

2 Unidirectional current without

emission of light

3. LED 2 Unidirectional conduction

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with emission of light

4. Capacitor

2 Momentarily deflection

5. Transistor

3 It consists of three terminals known as base, emitter

and collector6. Integrat

ed Circuit

(IC)

Multi

legs

Consisting of passive

elements like resistors and

active elements like diodes and transistors.

S.No.

Colour Code Resistance

Multimete

r Readi

ng

Difference

1.

2.

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3.

4.

5.

RESULT:

A diode, an LED, a transistor, an IC, a resistor, and a capacitor are identified from a mixed collection.

Resistance of carbon resistor were noted with a multimeter and compared with the calculated value.

PRECAUTIONS:

1. High voltage should not be applied as it may damage circuit elements.

2. Current in circuit should be constant.

SOURCES OF ERROR:44

1. Current in circuit may not be constant.2. Circuit elements may be damaged due

to supply of high voltage.

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