Question

Ohm's Law Name MWITTH Laboratory Report Questions: 1. If the switch were kept closed during the procedures, and the circuit components heated up. how would this effect the measurement of current (D)? Hint, think about how resistance (R) depends on temperature (T) for a carbon resistor. 2. For the rheostat, compute the values of resistance Rh and voltage drop Vh across the rheostat if, Vi-5.0V, the Ammeter reads I-0.056A, and the voltmeter reads Vs-1.69 V.

Answer 1

1. Carbon resistor is a negative thermal coefficient device. it means that the resistivity of the carbon resistance decreases with temperature. Thus, it will hamper the results as decreased value of resistance due to heating will increase the value of current.

2. The voltage supplied by the battery should be equal to the voltage drop across the devices connected. Here, $V_{h}$ is the voltage drop across the rheostat and $V_{s}$ is voltage drop across resistor. Voltage supplied by the battery is $V_{t}$.

Now, $5=1.69+V_{h}$

$V_{h}=3.31V$

Now, according to ohms law, $V=IR$

here $I$ is the current and $R$ is equivalent resistance.

For rheostat, $V_{h}=IR_{h}$

$R_{h}=\frac{V_{h}}{I}=\frac{3.31}{0.056}=59.10\Omega$