Physics

ATOMIC ENERGY CENTRAL SCHOOL, KAIGA

AISSCE 2010-2011

Name: M S SURAJClass: 12Section: BRoll No:

PHYSICS DEMONSTRATION

EXPERIMENTS

PHYSICS DEMONSTRATION PROJECT 2010-2011

DEMONSTRATION

EXPERIMENT FILE

Smt. Sangeetha NairPGT, PhysicsAECS, Kaiga

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PROJECT 2010-2011

SL.NO.

TOPIC PAGE NO.

01 TO DEMONSTRATE THE PRODUTION OF MAGNETIC FIELD WHEN ELECTRIC CURRENT PASSES THROUGH A COIL.

04

02 TO DEMONSTRATE THAT FOR THE SAME INCIDENT RAY, IF THE PLANE MIRROR IS ROTATED BY ANGLE THE REFLECTED RAY IS TURNED BY ANGLE 2θ.

06

03 TO DEMONSTRATE THE DIFFERENCE BETWEEN EMF AND TERMINAL POTENTIAL DIFFERENCE OF A CELL.

09

INDEX

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PROJECT 2010-2011

AIM:To demonstrate the production of the magnetic field

when electric current passing through a coil.

MATERIALS REQUIRED Insulated copper wire, a magnetic compass, one way

key, a non-magnetic circular frame, a battery and twowooden stands.

PROCEDURE

First of all wind 60 turns of insulated copper wire on a non- magnetic frame.

Take a tapping from the 30th turn and join it to the middle terminal Q at the base and join other ends of the insulated copper wire to terminals P and R at the base.

Place a magnetic compass in the centre of the circular coil with the help of wooden stand.

Now connect a battery E between the terminals P and Q through a key (K), an ammeter (A) and a rheostat (Rh) as shown in figure.

Switch on key (K) and vary the electric current with the help of rheostat.

Note the value of electric current and corresponding deflection in each case.

Also determine the radius of circular coil.

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CONCLUSIONThe readings show that the magnetic field is

produced when the electric current passes through the coil. It is also seen that on increasing the value ofcurrent and the no. of turns in the coil, the deflectionincreases and hence the magnetic field increases.

determine magnetic field produced by the relation

B = BH tanө

= µONi / 2r

In each case, by putting the value of I, N and r, the magnitude of the magnetic field can be determined. This can also be verified by finding the product of BH

and tanө where BH is horizontal component of the earth’s magnetic field and ө is the deflection produced in the pointer of magnetic compass.

Now connect the battery E between P and R so that 60 turns are in the circuit and repeat the experiment above.

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AIM: To demonstrate that for the same incident ray, if the

plane mirror is rotated by an angle θ, the reflected ray isturned by an angle 2θ.

MATERIALS REQUIREDA plane mirror holder, drawing pins, drawing board,

white paper and alpines.

THEORYConsider a ray of light PO incident on a plane mirror at

point O. It will be reflected along OQ according to laws ofreflection when it is in position AB. If α is the glancingangle as shown in figure, then the deviation suffered bythe reflected ray is given by ∠QOT = 2α

Suppose the plane mirror is rotated through angle θ sothat it comes in position A’B’. In this case, the incident rayremains same but the glancing angle changes to

∠POA’ = θ + α

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Suppose the ray of light after reflection follows the path OQ’. Therefore , the deviation in the path of reflected rayis given by

∠Q’OT = 2(θ + α)Let Φ be the angle through which the reflected ray turnson rotating the mirror through angle ө. Then

Φ = ∠Q’OQ

Φ = ∠Q’OT - ∠QOTFrom above equations, we have

Φ = 2(θ +α) - 2α Φ = 2θ

Hence if mirror is rotated through a certain angle, then reflected ray rotates through double angle.

PROCEDURE Fix a white sheet on a drawing board with the help

of drawing pins. Draw the line AB and A’B’ inclined at angle ө on the

white paper. Draw a line PO making a suitable angle of incidence

with the normal ON to line AB. Also draw the normalON' to the line A’B’ .

Now place the mirror on the line AB with the help ofmirror holder and fix two pins P and R at a distanceof 10 cm as shown in figure.

Also fix two more pins Sand Q such that images ofpins P and R and pins Sand Q appear to be in thesame straight line.

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CONCLUSIONAs per the observations, ∠QOQ' is twice of the

angle ∠AOA', it verifies that if plane mirror is turnedthrough a certain angle, the reflected ray turns throughdouble the angle.

Rotate the mirror AB to the position A'B' and fix the pins S’ and Q’ such that images of the pins P and R and the pins S‘ and Q' appear to be in the same straight line.

Join OSQ and OS'Q' and measure the angle ∠QOQ' by using protractor.

Repeat the experiment by taking different values of ө.

Note the readings in the table given below.

OBSERVATIONS

S.NO. Angle of rotation ofplane mirror

∠AOA i.e. θ

Angle of rotation ofreflected ray∠QOQ’ i.e. Φ

1

2

3

4

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AIMTo demonstrate the difference between E.M.F. and

terminal potential difference of a cell.

MATERIALS REQUIREDA primary cell (for example freshly prepared Leclanchecell), a one way key, a resistance box (0 to 500 ohm) and ahigh resistance voltmeter.

THEORY

It is defined as the maximum potential difference between the two terminals of the cell when no current is drawnfrom the cell. It is denoted by Ɛ and the S.I unit of emf isvolt(joule per coulomb).

It is defined as the potential difference between the terminals of a cell when the electric current is drawn fromthe cell. It is denoted by V. the S.I unit of T.P.D. is also volt(joule per coulomb).

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Consider a cell of emf E is connected across a resistance R provided by a resistance box and a key K. As key K isON , an electric current I starts flowing in the circuit .i.e. I = E / (R + r)Where r is the internal resistance of the cell.Or E = I (R + r)Or E = iR + IrBut the terminal potential difference of the cell i.e.,

V = iRThus we have

E = V + iRFrom the above , it is observed that the emf of the cell is greater than the terminal potential difference of the cell.

PHYSICS DEMONSTRATION PROJECT 2010-2011

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PROCEDURE First of all draw a neat and labeled diagram as shown in

figure. By using sand paper, clean the ends of connection wire

to remove the insulation. Now arrange all the apparatus according to the electric

circuit diagram. Note down the list count of the volt meter. Keep the electric circuit open (i.e. keep the key in OFF

state) and observed the potential difference by volt meter (that will be equal to the emf of the cell).

Now take out some resistance (say 5 ohm) from the resistance box and close the key K.

Record the value of volt meter (that will be equal to the terminal potential difference of the cell).

Now repeat the steps (5) to (7) four more times for different values of R (say 6 ohm, 7 ohm, 8 ohm & 9 ohm).

S.NO. ExternalResistance (R)

in Ω

The value ofE.M.F (whenkey is OFF ) in V

The value of T.P.D ( when key is ON ) in V

1

2

3

4

5

OBSERVATIONSThe least count of a voltmeter = …………… volt

Table for observations of E.M.F and T.P.D of a cell

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CONCLUSION

From observation table, it is observed that the emf of a cell is greater than the terminal potential difference across its terminals.