Calculate the total resistance and voltage for a series circuit with R1=15Ω, R2=30Ω, R3=45Ω and I=1.5A. Also, find the energy consumed by a 100W bulb used for 8 hours.

Here are the solutions to the problems.

** (Circuit with three resistors in series):**

Step 1: Calculate the total resistance of the series circuit.
Given resistors: $R_1 = 15 \, \Omega$, $R_2 = 30 \, \Omega$, $R_3 = 45 \, \Omega$.
For resistors connected in series, the total resistance ($R_{total}$) is the sum of the individual resistances:

$$R_{total} = R_1 + R_2 + R_3$$ $$R_{total} = 15 \, \Omega + 30 \, \Omega + 45 \, \Omega$$ $$R_{total} = 90 \, \Omega$$

Step 2: Calculate the total voltage applied to the circuit using Ohm's Law.
Given total current ($I$) = $1.5 \, \text{A}$.
According to Ohm's Law, the total voltage ($V_{total}$) is given by:

$$V_{total} = I \times R_{total}$$ $$V_{total} = (1.5 \, \text{A}) \times (90 \, \Omega)$$ $$V_{total} = 135 \, \text{V}$$

The total voltage applied to the circuit is $\boxed{\text{135 V}}$.

** (Electrical energy and power rating):**