27. Resistors & DC Circuits

In Ohm's Law, the variable letter $I$ stands for what physical quantity, and is measured in which unit?

Draw a circuit diagram for the circuit of FIGURE EX28.1.

According to Ohm's Law, which of the following correctly relates the voltage $V$, current $I$, and resistance $R$ in a resistor?

Electricity can be a hazard in hospitals, particularly to patients who are connected to electrodes, such as an ECG. Suppose that the motor of a motorized bed shorts out to the bed frame, and the bed frame’s connection to a ground has broken (or was not there in the first place). If a nurse touches the bed and the patient at the same time, the nurse becomes a conductor and a complete circuit can be made through the patient to ground through the ECG apparatus. This is shown schematically in Fig. 26–79. Calculate the current through the patient.

Four resistors with resistances $R_1$, $R_2$, $R_3$, and $R_4$ are connected in series to a battery with voltage $V$. What is the total current flowing through the circuit?

(II) A rectangular solid made of carbon has sides of lengths 1.0 cm, 2.0 cm, and 4.0 cm, lying along the x, y, and z axes, respectively (Fig. 25–36). Determine the resistance for current that passes through the solid in the x direction (Assume the resistivity is ρ = 3.0 x 10^-5 Ω m).

A copper transmission cable $100$ km long and $10.0$ cm in diameter carries a current of $125$ A. How much electrical energy is dissipated as thermal energy every hour?

If two resistors with resistances $R_1$ and $R_2$ are connected in series, what is the effective resistance $r$ of the system?

Which of the following equations represents Ohm's Law?

Calculate the terminal voltage for a battery with an internal resistance of 0.900 Ω and an emf of 6.00 V when the battery is connected in series with a 610-Ω resistor.