ACTIVITY-1

AIM: To assemble the components of a given electrical circuit.

APPARATUS and MATERIAL REQUIRED: Resistor, ammeter, (0-1.5A) voltmeter (0-
5V), battery, one way key, rheostat, sand paper, connecting wires.
PRINCIPLE: An electrical circuit is functional only if all the components of the circuit are
connected in proper order, assuming that all circuit components/devices are in working
condition and key is closed. The positive terminal of the battery should be connected to the
positive terminal of ammeter and positive terminal of the voltmeter. The ammeter should be
connected in series with the resistor and the voltmeter should be connected in parallel with
the resistor.
RESULT: The components of the electrical circuit were assembled.
PRECAUTIONS:
1. The positive terminal of the battery should be connected to the positive terminal of
ammeter and positive terminal of the voltmeter.
2. The ammeter should be connected in series with the resistor and the voltmeter should
be connected in parallel with the resistor.
3. Sand paper should be used to clean the ends of connecting wires and leads of the
component terminals. Grease/oil or oxide layer on their surfaces is insulating in nature
and needs to be removed. However, do not clean the plugs and keys with sand paper.
Excessive use of sand paper in such a case will make the plug unfit to be used with the
key.
DISCUSSION:
1. Draw the circuit diagram of the experiment before you start connecting apparatus and
keep in front of you.
2. The values of the resistances and the current carrying capacity of the rheostat are
given on a plate fixed on the body of rheostat.
 (with pencil on Blank side)

DIAGRAM:

Fig.: Assembling of given components

 ACTIVITY- 2
AIM: To draw the diagram of given open circuit comprising at least a battery,
resistor/rheostat, key, ammeter and voltmeter. Mark the components that are not connected in
proper order and correct the circuit and also the circuit diagram.
APPARATUS and MATERIAL REQUIRED: A given open circuit comprising at least a
cell or a battery, plug key, resistor, rheostat, ammeter, voltmeter, connecting wires and sand
paper.
PRINCIPLE: An electrical circuit is functional only if all the components of the circuit are
connected in proper order, assuming that all circuit components/devices are in working
condition and key is closed. An open circuit means a break in some part of a circuit which
could be deliberate such as a key in open position or a fault such as broken wire or burnt out
component(s) or loose connection.
RESULT: The electrical circuit assembled as per the corrected circuit diagram is functional.
PRECAUTIONS:
1. Ends of the connecting wires should be cleaned with sand paper before making
connections.
2. The positive terminal of the battery should be connected to the positive terminal of the
voltmeter and positive terminal of the ammeter.
3. The ammeter should be connected in series with the resistor and the voltmeter should
be connected in parallel with it.
DISCUSSION:
1. (a) Rheostat can be used in series as a variable resistance. In this case, the end
terminal(1) and the other variable terminal is to be used [Fig. 2(a)].

(b) When rheostat has to be used as a potential divider across the cell, the variable
voltage is derived using any one endterminal and the variable terminal of the rheostat
[Fig.2(b)]

2. Key is to be kept “OPEN” so that no damage to the components occur.

 (with pencil on Blank side)

DIAGRAM:

Fig 1: Open Circuit Diagram

Fig2: (a) Rheostat as a variable resistor (b) Rheostat as a potential divider giving variable voltage
 ACTIVITY- 3
AIM: To study the variation in potential drop with length of a wire for a steady current.
APPARATUS and MATERIAL REQUIRED: Potentiometer, battery eliminator of
constant voltage, dc power supply or lead accumulator, voltmeter and ammeter of suitable
range, plug key, jockey, rheostat, connecting wires, etc.
PRINCIPLE: If a steady current is flowing through a wire of uniform area of cross section
and having its resistance per unit length constant, potential drop V across two points of the
wire is directly proportional to the length l between those two points.
Mathematically,
V α l

RESULT: The ratio V/ l = φ is found to be constant within the limits of experimental error.
Its mean value is V cm–1.

PRECAUTIONS
1. Zero error in the voltmeter and ammeter (if there is any) should be corrected by
adjusting the screw provided at the base of the needle.
2. The current in the wire should remain constant throughout the experiment. To ensure
this, current should be drawn intermittently for short duration of time. It should be
monitored by an ammeter and readjusted whenever necessary, with the help of a
rheostat.
3. Do not press the wire too hard with the jockey while noting down the observations or
else there is a possibility that the wire will become non-uniform (diameter will
change) at these points during the course of time.
4. Check for uniformity of wire at its various points before the start of the experiment. If
wire is non-uniform, the potential gradient will not be constant.
SOURCES OF ERROR:
1. The wire must have a uniform cross section along its entire length. This should be
checked by measuring its diameter at various points before the start of the experiment.
2. Voltmeter may not give accurate reading.
DISCUSSION:
1. The potentiometer wire is connected firmly to thick copper strips after every 100 cm
of its length of 400 or 1000 cm. However, these small sections of wire do not
contribute to the total length of the potentiometer wire since electrical current flows
through the copper strips rather than the potentiometer wire in these sections.
2. Potentiometer has the advantage that it draws no current from the voltage source being
measured. As such it is unaffected by the internal resistance of the source
 (with pencil on Blank side)
DIAGRAM:

Fig: Circuit to study variation in potential drop

OBSERVATIONS:
Range of the voltmeter = ... V
Least count of the voltmeter = ...V
S. No. Length of potential wire over Voltmeter reading V ɸ = V/l
which potential drop is measured l (V) (V cm–1)
(cm)
1

CALCULATIONS:

Mean = = …….. V/m

5
 ACTIVITY-4
AIM: To identify a diode, a LED, a transistor, an IC, a resistor and a capacitor from a mixed
collection of such items.
APPARATUS and MATERIAL REQUIRED: Multimeter, a collection of diode, LED,
transistor, IC, resistor and capacitor.
PRINCIPLE:
1. A diode is a two-terminal device. It conducts when forward biased and does not
conduct when reverse biased. It does not emit light while conducting.
2. A LED (light emitting diode) is also a two-terminal device. It conducts when forward
biased and does not conduct when reverse biased. It emits light while conducting.
3. A transistor is a three-terminal device. The terminals represent emitter (E), base (B)
and collector (C).
4. An IC (integrated circuit) is a multi-terminal device in the form of a chip.
5. A resistor is a two-terminal device. It conducts equally in both directions.
6. A capacitor is a two-terminal device. It does not conduct but stores some charge when
dc voltage is applied.
S. No. Name of Device No. of Legs State of Conduction
1 DIODE 2 Conducts in one direction only
without any emission of light
2 LED 2 Conducts in one direction only with
emission of light
3 TRANSISTOR 3 Three terminal device; conducts in
one direction only between central
terminal and either of the remaining
two terminals
4 RESISTOR 2 Conducts in both directions
5 CAPACITOR 2 Does not conduct, gives an initial
deflection which decays to zero

PRECAUTIONS:
1. While obtaining resistance of any component, clean its leads properly.
SOURCES OF ERROR:
1. While checking resistance of a component, avoid touching either of the metal ends of
the multimeter leads. Body resistance in parallel with component resistance can affect
the resistance measurement.
 (with pencil on Blank side)
DIAGRAM:

Fig (a): Diode

Fig (b): LED

Fig (c): Carbon Resistors

Fig(d): Transistor

Fig(e): Integrated Circuits

Fig(f): Capacitors
 ACTIVITY-5
AIM: To observe refraction and lateral deviation of a beam of light incident obliquely on a
glass slab.
APPARATUS and MATERIAL REQUIRED: Drawing board, rectangular glass slab,
white sheet of paper, adhesive tape (cello-tape), drawing pins, a metre scale, flat-head pins,
protractor, sharp pencil and eraser.
PRINCIPLE: When a ray of light is incident on a rectangular glass slab, it is refracted
through it. It emerges out of the slab parallel to the direction of the incident ray. The
emergent ray suffers only a lateral displacement. For a given angle of incidence and a pair of
media, the lateral deviation is proportional to the thickness of the glass slab.
RESULT
1. The ray of light emerging from a glass slab is parallel to the incident ray direction, but
is laterally deviated.
2. The lateral deviation of the emergent ray with respect to the incident ray is directly
proportional to the thickness of the glass slab.
PRECAUTIONS:

1. While fixing the pins P and Q or the pins R and S, care should be taken to maintain a
distance of about 2 cm between the two pins.
2. The glass slab should be perfectly rectangular with all its faces smooth
SOURCES of ERROR:
1. The glass slab should not have any air-bubbles.
2. All measurement of angles using protractor should be done accurately.
 (with pencil on Blank side)
S.No. Thickness of Angle of Angle of Lateral
Glass Slab t Incidence i Emergence e Displacemnet d
1

2
 ACTIVITY-6
AIM: To observe diffraction of light due to a thin slit.
APPARATUS AND MATERIAL REQUIRED: Two razor blades, one adhesive tape/cello-
tape, source of light (electric bulb/ laser pencil), a piece of black paper, two glass plates.
PRINCIPLE When a beam of light passes through a fine opening (aperture) or around a
sharp obstacle, it bends around corners of the obstacle/aperture. The light beam spreads and
penetrates into the geometrical shadow of the obstacle. This phenomenon of bending of light
around fine openings/obstacles is called diffraction and is one of the evidences in favour of
wave nature of light. It arises because of the interference of light waves from different points
of the same wave front. Two razor blades with their sharp edges held parallel, quite close to
each other (separation being of the order of wavelength of light λ) form a fine single slit. The
diffraction pattern due to a single slit consists of a central bright band, surrounded on both
sides by coloured bands (with electric bulb) and alternate dark and bright bands (with laser
pencil) of decreasing intensity and fringe width.
RESULT: Light waves incident on very fine apertures (openings) bend arround corners and
exhibit phenomenon of diffraction.
DISCUSSION :
1. The sharpness of diffraction fringes depends mainly on the extreme fineness of the slit,
made using razor blades, keeping them quite close to each other.
2. Monochromatic light from a laser pencil is preferred over ordinary electric bulb for
obtaining better effect on the screen. With ordinary light (an electric bulb) not many fringes
are observed clearly, while with a monochromatic source (laser pencil) a large number of
distinct bright and dark fringes are observed for a reasonable width of the slit.
 (with pencil on Blank side)

Fig: A fine slit made by using two razor blades, one glass plate
and a piece of black paper.