Question

1. when you touch an electric wire and get a shock, what can you infer about the resistance of your body compared to the resistance of the circuit?

1. calculate: a device draws 40 a of current from a 12 - v battery. what is its power?

how does an electric circuit work?

1. identify the parts that make up the circuit in a laptop computer. describe what happens inside the circuit when the computer is on.

Explanation:

Question 19 (Calculation)

Step 1: Recall the power formula

The formula for electrical power \( P \) is \( P = V \times I \), where \( V \) is voltage (in volts) and \( I \) is current (in amperes).

Step 2: Substitute the given values

We are given \( I = 40 \, \text{A} \) and \( V = 12 \, \text{V} \). Substituting these into the formula:
\( P = 12 \, \text{V} \times 40 \, \text{A} \)

Step 3: Calculate the result

\( 12 \times 40 = 480 \), so the power \( P = 480 \, \text{watts} \) (since \( \text{V} \times \text{A} = \text{W} \)).

1. Parts of a laptop circuit:

• Power source: The laptop battery (or AC adapter) provides voltage (\( V \)) to drive current.
• Conductors: Wires (usually copper traces on the motherboard) that carry electric current.
• Loads: Components like the CPU, GPU, RAM, and hard drive (these convert electrical energy to other forms, e.g., heat, light, or computational work).
• Control elements: Switches (e.g., the power button) and transistors (to regulate current flow).

1. What happens when the computer is on:

• The power source (battery/adapter) pushes electrons through the conductors (wires/traces).
• Current flows to the loads (e.g., CPU, RAM). Loads use electrical energy: the CPU processes data, the screen lights up (converting electricity to light), and the hard drive spins (converting to mechanical energy).
• Control elements (transistors, power button) regulate current: the power button closes the circuit to start the flow, and transistors manage voltage/current to components.
• The circuit is a closed loop, so electrons flow from the negative terminal of the power source, through components, and back to the positive terminal (or vice versa, depending on DC polarity).

Answer:

The power of the device is \( \boldsymbol{480 \, \text{W}} \) (or 480 watts).

Question 20 (Description)