In a circuit with an applied voltage of 30 volts, what is the voltage drop across a 10-ohm resistor in series with a 20-ohm resistor?

To determine the voltage drop across a specific resistor in a series circuit, it is essential to understand how voltage divides among the resistors. When resistors are connected in series, the total voltage across the circuit is divided among the resistors in proportion to their resistances.

In this case, you have a circuit with a total applied voltage of 30 volts, consisting of a 10-ohm resistor and a 20-ohm resistor in series. The total resistance of the circuit can be calculated by adding the individual resistances together:

Total resistance, ( R_{total} = R_1 + R_2 = 10 , \Omega + 20 , \Omega = 30 , \Omega ).

Next, you find the current flowing through the circuit using Ohm's Law, which states that ( V = I \times R ). Rearranging it gives ( I = \frac{V}{R} ):

Current, ( I = \frac{30 , V}{30 , \Omega} = 1 , A ).

Now that you have the current, you can find the voltage drop across the 10-ohm resistor using Ohm's Law again:

Voltage drop across