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RESULT

1. Straight line nature of the I-V graph or V-I graph shows that potential difference
across the conductor is directly proportional to the current flowing through it,
i.e., V x /. This proves the Ohm’s law graphically.
2. The resistance of nichrome (or manganin) wire obtained from the graph is
equal (or approximately equal) to the mean calculated value of R. It also
verifies the Ohm’s law.
3. The resistance of the given wire =………..Ω

PRECAUTIONS

1. The ends of connecting wire should be neat and clean.
2. All connections should be kept tight.
3. Positive terminal of ammeter or voltmeter should be connected to positive
terminal of the battery or battery eliminator.
4. The ends of resistance wire must be connected across the terminals of
voltmeter.
5. Never allow the current to flow in the resistance wire for a longer time to avoid
heating effect of current as R∝ T.
6. Range of voltmeter should be greater than the applied voltage.
7. A low resistance ranged rheostat must be used.
8. The area of cross-section of the connecting wire should be more because it
offers negligible resistance.

SOURCE OF ERROR

1. Reading error may be possible while observing the pointer of ammeter and
voltmeter.
2. Thick connecting wires may not be available at the time of performing the
experiment.
3. Area of cross-section of resistance wire may not be uniform across the length
of wire.
4. There may be the use of. a high resistance rheostat.
5. Current may be allowed for a longer period of time.
6. The terminal screw of the instrument may not be tightened properly.

INTERACTIVE SESSION

Question 1:
Which basic law of electricity is verified by you from this experiment?

Question 2:
State Ohm’s law..

Question 3:
In which unit current is measured?.