Explain the
relationship
between
the
current and
the
resistance in the
circuit x which have
IA and Grand circuity
which have
2 A and ov,
Answers
Answer:
You might expect that there is a simple relation between voltage and current, and sure enough, the German scientist Georg Ohm discovered that, for many materials, there is a linear relationship between the two. Ohm’s law states that the current I passing through a material connected to a voltage V is given by the simple equation I = V/R. Here, 1/R is the constant of proportionality and is called electrical resistance and you can see why from the equation: a material with a very large value of R will pass almost no current (bad conductor), while a material with very small R will yield a large current for the same voltage (good conductor). So the term has exactly the same meaning as it has in ordinary speech, e.g. the French resistance. Resistance is measured in volts per amp, also known as Ohms (Ω).
Voltage_vs._Current
Many materials have a linear relation between voltage and current – the slope of the graph is the material’s resistance
In the experiment, the students apply a series of voltages to an unknown resistance in a circuit, and record the corresponding currents. A plot of voltage versus current then allows them to verify the linearity of the relation and the resistance is estimated from the slope of the line. (Strictly speaking, one should really put the voltage on the x-axis as it is the independent variable, but the calculation is simpler if the voltage is on the y-axis).
Measuring current and voltage
All of the above is fine in principle. Yet novices find the measurements quite difficult in practice. They have problems connecting the circuit because they get confused between measuring the current that flows through a device, and the voltage across it. It’s crucial to understand the difference between the two, and I suspect the modern multimeter adds to the confusion.
simple-circuit-diagram
The ammeter reads the current running through the resistor while the voltmeter reads the voltage across it. A plot of voltage vs current gives a measurement of the resistance
When I was a student, the current was measured by passing the current through an ammeter (marked A in the diagram), an analog device with a nice big dial calibrated in amps or milliamps. The voltage across the resistor was measured by connecting a different instrument, the voltmeter, across the terminals of the resistor; this voltmeter was a separate meter with a dial calibrated in volts (marked V in the diagram). So an ammeter was always connected in series with the resistor/device, while the voltmeter was always connected across it (in parallel).