ACTI VITY A4
AIM
To assemble the components of a given electrical circuit (say Ohm's law circuit used to
measure resistance)
APPARATUS AND MATERIAL REQUIRED
A resistor, an ammeter (0-1.5 A), a voltmeter (0-5 V), a battery/battery eliminator, one-way key, rheostat,
connecting wires and a piece of sand paper.
THEORY
For assenmbling the components of any circuit, it is advisable to connect the components in the following order.
1. Source of power (battery/battery eliminator).
2. Plug key (near the battery).
3. Resistors, bulbs, inductors or any other load (to be connected end to end).
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LAB MANUAL PHYSICS-XH
4 easuring instruments ammeter, voltmeter, metre bridge, Ppotentiometer
connected in series and voltmeter in parallel with the load with positive ends of etc.
8 Ammeter
ends of both
positive terminal of the battery.
CIRCUIT DIAGRAM
Battery Plug key Rh
HHE w
Rheostat
Fig. 9 Assembling the components for measurement of resistance by Ohm's law.
PROCEDURE
. Draw the circuit
diagram required for the given activity and arrange the
onents
components accordingly
aco
on the work table shown in
as
Fig. 9.
.Clean the ends of the with
connecting wires a piece
paper.of sand
3. Connect the battery, ammeter A, resistance R, rheostat Rh and plug key K all in
series and volt-
in parallel with resistor R. See that the positive ends of ammeter and voltmeter
are con
towards the positive terminal of the nected
battery.
4. Insert the
plug in the key K. See that the ammeter and voltmeter show detlections on the right han:
(positive) side. Adjust the rheostat so that the deflections are within scale. hand
5. The deflections in ammeter and voltmeter
verify the continuity of the assembled circuit.
CONCLUSION
The
components of the given electrical circuit have beern correctly assembled.
PRECAUTIONS
1. Before making the connections, clean the ends of the connecting wires with a
piece of sand paper.
2. Make neat and
tight connections.
3. The ammeter should be connected in series and
voltmeter in parallel with the resistor.
4. The positive ends of both ammeter and
voltmeter should be connected to the
the battery. positive terminal of
VIVAVOCE
1. What do you meant emf a of cell ?
An ammeter is connected in series in a circuit so that
The emf of a cell is equal to the
potential difference whole of the current, which it is required to measure,
between its terminals when no current is being drawn passes through it. Moreover, an ammeter has a low
from the cell. resistance, so its insertion in the series circuit does nor
2. Does the current drawn from the cell remain constant ? practically change the main current.
Ifnot, why? 4. Whyis a voltmeter connected in parallel to t
The current drawn from the cell decreases with the
COmponentacross which voltage is to be measured it
passage of time. After prolonged use, the decrease in en
Yoltmeter is a high resistance galvanometer.
the emf of a cell is very small but the increase in S Connected in parallel with a component, it adra
internal resistance is quite large.
very small current and most of the currerntp
3. Why is an ammeter always connected in series with through that component. Hence potential diree
the circuit ? across that component does not change appre
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