Activity 1
Aim
To assemble the components of a given electrical circuit
Apparatus
Resistor, ammeter, voltmeter , battery, one way key, rheostat, sand paper, connecting wires.
Theory
Current flows through complete circuit. Voltmeter must be connected in parallel to the resistor
and ammeter in series.
Circuit diagram
Procedure
1. Connect the components as shown in Figure.
2. After closing the key K, check that the voltmeter and ammeter show deflections on the
right hand side.
Result
The components of the electrical circuit were assembled.
Precautions (Any Two)
1. The connections should be neat, clean and tight.
2. Thick copper wires should be used for the connections after removing the
insulations near their ends by rubbing with sand paper.
3. Voltmeter and ammeter should be of proper range.
4. A low resistance rheostat should be used.
5. The key should be inserted only while taking observations to avoid heating of
resistance (otherwise its resistance will increase).
Sources of error (Any Two)
1. The instrument screws may be loose.
2. Thick connecting wires may not be available.
3. Rheostat may have high resistance.
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.
Theory
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.
Apparatus
Resistor, ammeter, voltmeter , battery, one way key, rheostat, sand paper, connecting wires.
Circuit diagram
Close circuit
Open Cicuit
Result
Circuit diagram for open and close circuit shown above.
Precautions (Any Two)
6. The connections should be neat, clean and tight.
7. Thick copper wires should be used for the connections after removing the insulations near
their ends by rubbing with sand paper.
8. Voltmeter and ammeter should be of proper range.
9. A low resistance rheostat should be used.
10. The key should be inserted only while taking observations to avoid heating of resistance
(otherwise its resistance will increase).
Sources of error (Any Two)
4. The instrument screws may be loose.
5. Thick connecting wires may not be available.
6. Rheostat may have high resistance
ACTIVITY: 3
To Observe Refraction & Lateral Deviation Of a Beam Of Light Incident Obliquely on
a Glass Slab
Aim
To observe refraction and lateral deviation of a beam of light incident obliquely on a glass slab.
Apparatus
Glass slab, drawing board, white paper sheet, drawing pins, office pins, protractor.
Theory
When a ray of light (PQ) incident on the face AB of glass slab, then it bends towards the normal
since refraction takes place from rarer to denser medium. The refracted ray (QR) travel along
straight line and incident on face DC of slab and bends away from the normal since refraction
takes place from denser to rarer medium. The ray (RS) out through face DC is called emergent
ray.
From the following diagram
1. The incident ray is parallel to the emergent ray i.e. i = e.
2. The emergent ray is laterally deviated from its original path (incident ray) by a
distance d called lateral displacement.
Diagram
Observation
Conclusions
1. Angle of incidence (i) = Angle of emergence (e).
2. The lateral displacement increases with the increase in the thickness of the slab.
3. The lateral displacement increases with the angle of incidence (i).
Sources of error:
1. There shouldn’t be any air bubbles in the glass slab.
2. The measurements done by the protractor should be accurate.
Precaution:
1. The angle of incidence should lie between 30° and 60°.
2. The distance between the pins P and Q or the pins R and S, about 5 cm gap should be
maintained.
Activity:4
Aim: To study the variation in potential drop with length of a wire for a steady current.
Material: Potentiometer A fully charged 4.5 V battery or battery eliminator, a low resistance
rheostat, a voltmeter of range (0-3.0 V), an ammeter (0-3) A, a one way key, a jockey, a set squ
are,
connecting wires and a piece of sand paper.
Table for length and potential drop
Length of potentiometer
Sl. No. Voltmeter reading V (volts) Ratio k = V/l (volt/cm)
wire l (cm)
Result: Potential drop per unit length of the wire is k= ……V cm-1
Precautions (Any Two)
11. The connections should be neat, clean and tight.
12. Thick copper wires should be used for the connections after removing the
insulations near their ends by rubbing with sand paper.
13. Voltmeter and ammeter should be of proper range.
14. A low resistance rheostat should be used.
15. The key should be inserted only while taking observations to avoid heating of
resistance (otherwise its resistance will increase).
Sources of error (Any Two)
7. The instrument screws may be loose.
8. Thick connecting wires may not be available.
9. Rheostat may have high resistance.
Activity 5
Aim
To identify a diode, a LED, a resistor and a capacitor from a mixed collection of such items.
Apparatus
Multimeter, a collection of diode, LED, resistor and capacitor
Theory
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.
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.
A resistor is a two terminal device. It conducts equally in both directions.
A capacitor is a two terminal device. It does not conduct but stores some charge when dc
voltage is applied.
Diagram
Observation
Sl no. State of Device Device Name
1 Conducts in both directions Resistor
2 Does not conduct, gives an initial deflection which Capacitor
decays to zero
3 Conducts in one direction only without any emission Diode
of
light
4 Conducts in one direction only with emission of light LED
Result
A diode, a LED, a resistor and a capacitor are identified respectively from a mixed collection.
Precaution
1. While obtaining resistance of any component, clean its leads properly.
2. Use the selector switch of the multimeter carefully for various measuring modes.
Sources of error
1. When the metal ends of a multimeter leads are touched, the multimeter should show
zero resistance. If it is not done, the resistance measurements are not reliable.
2. 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.
Activity 6
Aim
Use of multimeter to check unidirectional flow of current in a diode and LED
Apparatus
A multimeter, a diode, LED, plug key, a battery, resistance box, connecting wires and sand
paper.
Theory
A semiconductor junction diode, when connected (or biased) in the forward direction,
offers a low resistance. However, when it is biased in the reverse direction, it offers a very
high resistance.
Therefore, the working of a junction diode can be examined by measuring its resistance in the
forward and reverse bias conditions. The functioning of junction diode can also be examined
by checking the unidirectional flow of current in a circuit as shown in the figure below. For a
diode in proper working order, a substantial current (of the order of few mA) will flow in the
forward bias condition. If the polarity of the bias is reversed (i.e., diode in reverse bias
condition), negligible current (of the order of few µA) will flow.
LED also allow current in forward bias and glow.
Circuit diagram
Observation
Sl no. Forward bias Reverse Bias
Diode Low resistance, current High resistance, current in
in mA µA
LED Low resistance, current High resistance, current in
in mA, it glows µA, it does not glow
Result
Confirm diode and LED only conduct during forward bias.
Precaution
1. While obtaining resistance of any component, clean its leads properly.
2. Use the selector switch of the multimeter carefully for various measuring modes.
Sources of error
1. When the metal ends of a multimeter leads are touched, the multimeter should show
zero resistance. If it is not done, the resistance measurements are not reliable.
2. 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.
