## Investigatory Project on Parasitic Plants

A SURVEY OF PARASITIC PLANTS AND THEIR HOST SPECIFICITY

Introduction

Any organism that lives on the body of another organism and absorbs nutrients, wholly or partially is termed as parasite. Parasites absorb organic food from the host with the help of sucking roots called haustoria. The haustoria penetrate the host tissue and establish connection with the conducting system of the host plant. In plants different degrees of parasitism can be noted. They are total parasites and partial parasites. They may be stem or root parasites.

## Investigatory Project in Physics for Class 11

INVESTIGATORY PROJECT – 1

THE DEVIATION FROM OHM'S LAW

Aim: To study the deviation from ohm's law due to the change of temperature of the conductor.

Materials and apparatus

(i) A resistance wire (of resistance about 1 Ω) connected between two terminals which are fixed on a wooden strip.

(ii) Sensitive ammeter of range about 3A

(iii) Digital voltmeter

(iv) Rheostat

(v) Battery eliminator

(iv) Key etc

Procedure

Connections are made as shown in the figure. The current I and p.d across the resistance R are measured. V/I is calculated. Sufficient current is sent through the resistor by adjusting the rheostat so that it is heated. V/I is calculated. The experiment is repeated for different values of current. It is seen that V/I is not a constant and it increases with the increase in current.

INVESTIGATORY PROJECT – 2

THE SELF INDUCTION

Aim: This is a project to study the process of self induction.

Material required

(i) 6V torch bulb

(ii) 3-0-3, 500 mA transformer

(iii) A piece of PVC pipe

(iv) A wooden plank or card board piece

(v) Connecting wire

(vi) 22 gauge finely insulated copper wire about 100 gram

(vii) iron pieces

Procedure

Fix the transformer on the wooden plank. Connect the wires from the output of the transformer to the bulb. The middle wire should not be used. Wind about 450 turns of the copper wire on the PVC pipe and fit it on the board. The end B of the solenoid is connected to the bulb. Connect wires from P to C and from R to B. Apply 230 V ac mains to transformer. The voltage gets stepped down to 6V. The bulb glows. Disconnect the wire from R to B and connect it to the point A. The bulb will become dim. The ac when passed through the solenoid creates changing flux which induces the back end. Then the bulb becomes dim. If soft iron bars are introduced into the PVC pipe, the back emf increases due to increased flux density. Hence the effective voltage decreases and the bulb will become dimmer.

INVESTIGATORY PROJECT – 3

THE ELECTROMAGNETIC INDUCTION

Aim: This is a project meant to study electromagnetic induction.

Materials needed

(1) Finely insulated copper wire of gauge 24 about 100 gram

(ii) A piece of GI pipe

(iii) Magnet from a loud speaker

(iv) Two LEDs preferably of different colours.

Procedure

Wind about 450 turns of copper wire on the GI pipe and attach the two LEDs at the ends of the wire in such a way that they are in opposite directions. Move a magnet to and fro inside (or near) the coil very quickly. The coil will experience a change of flux. Hence an emf will be induced and current will flow. The LED will glow indicating the presence of current. When the magnet moves upward one LED will glow but when the magnet is made to move in the downward direction, the other LED will glow. This indicates that the current is reversing direction i.e., it is AC.

INVESTIGATORY PROJECT – 4

The IMPROVISED RESONANCE COLUMN

Aim: This project is meant to show resonance and to calculate the velocity of sound in air.

Materials needed

(i) A fused tube light

(ii) Tube of a cycle tyre

(iii) A stand

(iv) A tuning fork and a rubber hammer

Procedure

Both the ends of a fused tube light are carefully cut open. The inside surface of the tube is washed to remove the coating. Thus we get a tall glass tube for the resonance column. The glass tube is clamped vertically on a stand. A long cycle tube with both ends open is taken. One end of the tube is slipped on to the lower end of the glass tube. The other end of the rubber tube is closed by tying the end with a thread. The rubber tube is rolled up.

The glass tube is filled with water. An excited tuning fork of frequency f is kept horizontally over the mouth of the glass tube. The rubber tube is slowly unrolled so that the water level in the glass tube is slowly lowered and length of the air column inside the tube gradually increased till a booming sound is heard. Now the air column vibrates in resonance with the tuning fork. The length l of the air column is measured. The velocity v of sound at room temperature is calculated using the equation,

V = 4lf

INVESTIGATORY PROJECT – 5

THE BIASING OF A TRANSISTOR

You all know that the transistor is known as wonder child of electronics. This is a project to realize that a transistor work only when its emitter junction is forward biased and collector junction is reverse biased.

Materials needed

(i) A one kΩ resistor

(ii) A transistor - AD 149

(iii) A 6V bulb

(iv) Connectng wires

(v) 1.5 V torch cell

Procedure

Connect the resistor, transistor and bulb as shown in the figure. The transistor is PNP. Now apply 1.5 volt dc with positive at A and negative at B. The bulb glows. Now the emitter junction is forward biased and collector junction is reverse biased. Hence the transistor conducts. If the voltage is reversed the emitter junction will be reverse biased. Hence the transistor will not conduct. The bulb will not glow.

INVESTIGATORY PROJECT – 6

THE PULSE AMPLIFIER

Aim: This is a project meant to show the amplification.

Materials required

(i) Transistors BC 548, BC 558

(ii) LED

(iii) 100Ω resistor

Procedure

Arrange the devices as shown in the circuit. Our body has a small voltage. At the point A you touch with the finger. The body voltage is applied at the base. In the first transistor this voltage gets amplified and the output goes as input of the second transistor. Reamplification takes place. Output makes the LED glow. When we take off the hand from the base the whole process stops.

When the base of the first transistor BC 548 is touched the body voltage makes the base emitter junction forward biased. The transistor conducts and its amplified output is fed as the input of the second transistor BC 558. The second transistor amplifies its input and the amplified output makes the LED glow.

## Investigatory Project on Dispersal of Seeds by Various Agencies

Aim: Study of Dispersal of seeds by various agencies.

Introduction:

The process of distribution of seeds to long locations away from their parent is referred as dispersal. It helps the new plants to get more chances of getting water, better soil, nutrients, light and space for a better begin of life. The fruits and seeds shows many adaptations for improved dispersal through different agencies.

The dispersal of seeds and fruits are effected by natural agents such as wind (can be called as anemochory), water (can be called as hydrochory) and animals comprising man (can be called aszoochory). In some plants, they exhibit self dispersal under the explosive mechanism (can be called as autochory). Among these the dispersal through the agency of animals is believed to be  the best and most better method.

## Investigatory Project on Ecosystem

Investigatory Project on Ecosystem

Introduction

The term 'Ecosystem' expresses the relationship between a biotic community with its abiotic components. Ecosystem is the basic structural and functional unit of ecology. The term 'ecosystem' was coined by A. G. Tansley (1953). The ecosystem has two main structural components. They are biotic components and abiotic components. The biotic components consist of three groups - Producers, consumers and de-composers.

Materials and Methods

Nets, Herbarium, museum jars, dissection box, glass slides etc were collected. A pond from the local area (name of the place) was selected for the present study. A collection trip was arranged for this purpose. During this visit water samples were collected from the pond. The animals and plants from the pond were collected with the help of net and stored them in museum jars. The collected samples were brought to the laboratory. With the help of a thermometer atmospheric temperature and pond water were measured. Temporary mounts of various micro-organisms from the pond were prepared and identified them with the help of authentic books. The identified specimens were preserved in formalin.

Observation and Results

The biotic components collected from the pond ecosystem are noted in the table given below.

 No: Producers First order consumers Second order consumers Third order consumers Decomposers 1 Chlamydomonas Rotifers Planaria Large fish Bacteria 2 Navicula Amoeba Hydra Frog Bacteria 3 Volvox Daphnia Snail Fresh water snake Fungus 4 Asterionella Vorticella Leech - 5 Microcystis Actinophaerium Cyclops Terapin 6 Chara Dragonfly nymph Pond heron 7 Potamogeton Dragonfly nymph 8 Vallisneria Tad – pole larva of frog 9 Nymphaea Small fishes 10 Sagittaria

The atmospheric temperature and pond water measured is noted below.

Ecosystem – Pond

Atmospheric temperature – 34°C

Water temperature – 28°C

Discussions and conclusions

The biotic components of a pond ecosystem were collected and studied. The atmospheric temperature and pond water were measured and compared.

The primary producers collected from the pond were Chlamydomonas, Navicula, Volvox, Asterionella, Microcystis, Chara, Potamogeton, Vallisneria, Nymphaea and Sagittaria. Of these Chlamydomonas Navicula, Volvox, Asterionella, Microcystis were microscopic producers and Vallisneria, Nymphaea and Sagittaria were rooted hydrophytes.

The first order consumers collected and identified were, Rotifers (Producer - Chlamydomonas), Amoeba (Producer - Navicula), Daphnia (Producer - Volvox), Vorticella (Producer - Asterionella) and Actinophaerium (Producer - Microcystis). These consumers were microscopic. The planaria (Chlamydomonas  Rotifers  Planaria), hydra ( Navicula  Amoeba  Hydra), snail (Volvox  Daphnia  Snail), leech (Asterionella  Vorticella  Leech), cyclops (Microcystis  Actinophaerium  Cyclops), dragon fly nymph (Producer - Chara, Potamogeton), tad - pole larva of frog (Producer - Vallisneria) and small fishes (Producer - Nymphaea) were second order consumers. The large fishes, frog, fresh water snake, terrapins and pond heron were third order consumers. The decomposers were bacteria and Fungi.

There was an interdependence between pond ecosystem and its components. There was a transfer of food from producers through a chain of different levels of consumers and finally reached the decomposers through death and decay. This transfer of food from the producers through a chain of living beings with repeated eating and being eaten is called as food chain. The food chain were interconnected with each other to form a network called the food web.

This project helped us to study various components of pond ecosystem.

Viva Voce

1. What is an ecosystem?

The structural and functional unit of ecology

2. What are the components of an ecosystem?

Biotic components and abiotic components

3. Name any two microscopic producers.

Volvox, Chlamydomonas

## Investigatory Project on Eddy Current

INVESTIGATORY PROJECT ON EDDY CURRENT (also called Foucault's currents)

Electromagnetic induction takes place not only in circuits, but also in pieces of metals. Whenever the magnetic flux connected with a part of metal changes an induced current, and that current is called eddy current, will circulate inside it. Eddy current flows throughout the whole volume of the metal by forming different closed paths.

Since the resistance of the metal is small, eddy current is appreciable. It heats the metal and so is a waste of electrical energy. Eddy currents are undesirable in most of the electrical machineries like transformer, induction coil, choke coil etc.

Eddy current can be minimised by increasing the resistance of the metal. That is why laminated soft iron cores are used in transformers, electric generators, motors, chokes etc and cores made up of bundles of soft iron rods are used in induction coils. The direction of the eddy current is given by Lenz's rule.

Experiments to demonstrate the force exerted by eddy current

Experiment 1:

A light flat metallic disc is placed on the top of a cylindrical electromagnet. When the current is switched on, the flux linked with the disc changes from zero to maximum and, hence, eddy current is produced in the disc. If the upper end of the electro-magnet becomes north pole, the lower side of the disc acquires north polarity. The disc is seen to be thrown up because of the magnetic repulsive force, as the electromagnet is switched on.

Experiment 2: Waltenhofen's pendulum

The apparatus comprises of pendulum having a flat copper plate as its bob. It is set so that it suspends amid the poles of an electromagnet. So long as the magnetic flux linked with the pendulum does not change, the pendulum swings liberally. But as soon as the electro-magnet is switched on, the oscillations of the pendulum are closely damped and die away quickly. Since the pendulum swings up and down, the magnetic flux linked with it changes and consequently eddy currents are produced inside the copper plate, which in accordance with Lenz's law, oppose the motion of pendulum. Hence the pendulum comes to rest very quickly. If a number of slots are cut in the copper plate, eddy currents in the plate become much smaller compared to the former case as the length of the closed path of the current and hence the resistance of the path increases. So the damping is reduced and the pendulum comes to rest only slowly.

## Investigatory Project on Simple Pendulum

Physics Investigatory Project on Simple Pendulum

Aim: To study about the factors upon which the period of oscillation of a simple pendulum depends.

Apparatus: Simple Pendulum, Bob of different masses, Stop watch, Meter Scale etc.

A simple pendulum having a metallic bob hanged by a light inextensible string. The upper portion of the string is passed all the way through a split cork which is clamped strongly to a stand. The length of the pendulum is the distance between the point of suspension to the centre of gravity of the bob.

Theory:

The period of oscillation of a simple pendulum is given by,

T = 2π(l/g)

Where, l = length of the pendulum

g = acceleration due to gravity at the place

Procedure:

1. To study how the length of the pendulum depends

The pendulum is suspended from a fixed point. The length of the pendulum is adjusted to be about 50 cm. The time for 20 oscillations is determined and the period of oscillation is calculated. The experiment is repeated for different lengths and in each case the period is calculated.

2. To study how the amplitude of the pendulum depends

The experiment is repeated by keeping the length as a constant for different amplitudes (we prefer small amplitude). For this the edge of the table parallel to the plane of oscillation of the pendulum is marked at different distances from the mean position so as to represent different amplitudes. The period of oscillation is found for different amplitude of oscillations.

3. To study how the mass of the bob depends

The experiment is repeated by using bobs of different masses keeping the length of the pendulum and amplitude constant. The period of oscillation is determined in each case.

Observations and Calculations

i. To study how the length of the pendulum depends

Amplitude of oscillation = ...........cm

Mass of the bob = ........g

 Trial No: Length of the pendulum Time for 20 oscillations Period, T = t/20 1 2 Mean(t) cm s s s s 1 2 3 4 5 6

ii. To study how the amplitude of the pendulum depends

Length of the pendulum = .......cm

Mass of the bob = .......g

 Trial No: Length of the pendulum Time for 20 oscillations Period, T = t/20 1 2 Mean(t) cm s s s s 1 2 3 4 5 6 4 8 12 16 18

iii. To study how the mass of the bob depends

Length of the pendulum = .......cm

Amplitude of oscillation = .......cm

 Trial No: Mass of the bob Time for 20 oscillations Period, T = t/20 1 2 Mean(t) g s s s s 1 2 3 4 5 6 4 8 12 16 18

Report:

It is found that the period of oscillation of a simple pendulum at a place,

i. depends on the length of the pendulum

ii. independent of the amplitude of oscillation

iii. independent of the mass of the bob