How to calculate a voltage drop across a single resistor?

A box contains $20$ resistors with $15$ pcs of $100\ \omega$ and $5$ pcs of $50 \ \omega$. What is the probability that the second resistor is $100 \ \omega$, given that the first resistor is $50 \ \omega$?

A DC circuit is formed by a 12 V battery and a 5-ohm resistor. Find the current Ir flowing through the resistor. Express your answer to 3 significant figures and include the appropriate unit.

Air is pumped into the top of the tank so that the pressure at $B$ is $40\ \mathrm{kPa}$. Calculate the discharge of the water as a function of the height $h$. Plot the discharge (vertical axis) versus $h$ for $1 \mathrm{~m} \leq h \leq 6 \mathrm{~m}$. Give values for increments of $\Delta h=1 \mathrm{~m}$.

You have been handed an unknown battery. Using your multimeter, you determine that when a $5.00-\Omega$ resistor is connected across the battery's terminals, the current in the battery is $0.500 \text{~A}$. When this resistor is replaced by an $11.0-\Omega$ resistor, the current drops to $0.250 \text{~A}$. From those data, find $(b)$ internal resistance of the battery.

An 18.0 $\Omega$, 9.00 $\Omega$, and 6.00 $\Omega$ resistor are connected in series with an emf source. The current in the 9.00 $\Omega$ resistor is measured to be 4.00 A. Find the potential difference across the emf source.

What is the value of resistor $R$ as we discussed earlier?

The resistor, inductor, capacitor, and voltage source described in earlier Exercise are connected to form an $L-R-C$ series circuit.(d) What are the voltage amplitudes across the resistor, inductor, and capacitor?

A 50.0-V resistor, a 0.100-H inductor, and a 10.0-$\mu \mathrm { F }$ capacitor are connected in series to a 60.0-Hz source. The rms current in the circuit is 2.75 A. Find the rms voltages across the resistor.

Which one gives off more power (as joule heating) when connected across the terminals of a 12-V battery: a $5.0-\Omega$ resistor or a $10-\Omega$ resistor? Explain your reasoning.

What is the voltage difference across the 9- $\Omega$ resistor?

Two conducting rails 30 cm apart rest on a 5.0$\degree$ ramp. They are joined at the bottom by a $0.60 ~\Omega$ resistor, and at the top a copper bar of mass $0.040$ kg is laid across the rails. The whole apparatus is immersed in a vertical $0.55 ~\mathrm{T}$ field. What is the terminal (steady) velocity of the bar as it slides frictionlessly down the rails?

Two identical resistors are connected in series to a 12.0 V battery. The total resistance of the circuit is 16 $\Omega .$ (a) Calculate the voltage drop across each resistor. (b) Calculate the current through each resistor.

A $6 \mathrm{~V}$ source is connected to a $100 \Omega$ resistor by two $12 \mathrm{ft}$ lengths of 18 gauge copper wire. The total resistance is the resistance of both wires added to the $100 \Omega$ resistor. Determine the following: (a) Current (b) Resistor voltage drop (c) Voltage drop across each length of wire