*Question T5D13:
In which type of circuit is DC current the same through all components?*  

*Correct Answer is  A: Series*  

### AI Response: (may contain errors)  

In a series circuit, the same amount of DC current flows through all components. This is due to the nature of series connections, where components are connected end-to-end, creating a single path for current flow.

### Explanation of the Correct Answer:
- **Series Circuit (Correct Answer: A)**:
  - In a series circuit, the total current ($I$) is the same through each component because there is only one path for the current to travel. This can be expressed as:
  
  $$I_{total} = I_1 = I_2 = I_3 = ... = I_n$$
  
  where $I_n$ represents the current through each component.

### Explanation of Incorrect Choices:
- **Parallel Circuit (Choice B)**:
  - In a parallel circuit, the voltage across each component is the same, but the current can vary. The total current is the sum of the currents through each branch:
  
  $$I_{total} = I_1 + I_2 + I_3 + ... + I_n$$
  
  Here, $I_n$ can differ for each branch depending on the resistance.

- **Resonant Circuit (Choice C)**:
  - A resonant circuit is not defined by current flow but rather by its ability to resonate at a particular frequency. It typically involves inductors and capacitors and does not imply that current is the same through all components.

- **Branch Circuit (Choice D)**:
  - A branch circuit refers to any circuit that branches off from a main circuit. In a branch, the current can vary depending on the components connected, similar to a parallel circuit.

### Summary:
- In a series circuit, the current is constant through all components, making it the correct answer.
- In parallel circuits, currents can differ; resonant circuits focus on frequency, and branch circuits can have varying currents as well. 

Understanding these distinctions is crucial for the Extra Class exam and practical applications in amateur radio.