In designing an experiment to verify Ohm's Law, a student uses a resistor, an ammeter, and a voltmeter. Which step is most essential to ensure that the data support Ohm's Law for the resistor?
Vary the applied voltage and record the resulting current at each step
Ohm’s law states that the current through a conductor is directly proportional to the potential difference across it at constant temperature, \(V = IR\). To show this proportionality, the experiment needs several pairs of \(V\) and \(I\) readings for the same resistor.
So the student must change the applied voltage step by step (for example by adding cells or using a rheostat) and record the current from the ammeter each time. If \(V/I\) stays the same and the \(V\)–\(I\) graph is a straight line through the origin, the data support the law.
Measuring only power at one fixed voltage, or keeping the voltage constant, gives just a single reading and cannot show how current changes with voltage. Replacing the resistor with different materials changes the resistance itself, so the readings would no longer test one resistor.
Hence, Vary the applied voltage and record the resulting current at each step.
Similar Questions
Two circuits have the same voltage source. The first has resistance R with current I1, while the second has twice the resistance of the first with current I2. Find the ratio of the current (I1/I2) in the two circuits.
Important Questions from Ohm’s Law
Three resistors having resistances in the ratio 1 : 2 : 3 are in parallel. The current through the resistors are in the ratio
Which of the law states that in any closed circuit the current is directly proportional to the voltage, provided the physical conditions of the circuit are kept constant?
According to Ohm’s law, if current (I) increases and potential difference (V) remains constant, then:
Fill in the blank with the most appropriate option.
18 volts = _________ × 3 ohms.
- ______ states that the electric current flowing through a metallic wire is directly proportional to the potential difference ‘V’ across its ends provided its temperature remains the same.
