An energy source will supply a constant current into the load if its internal resistance is

Options

A. very large as compared to the load resistance
B. equal to the resistance of the load
C. non-zero but less than the resistance of the load
D. zero

Explanation

To determine the internal resistance of an energy source that will supply a constant current into a load, we can analyze the circuit and the relationship between the current, voltage, and resistance.

### Step-by-Step Solution:

1. **Understanding the Circuit**:
- We have an energy source (like a battery) with an electromotive force (emf) denoted as \( E \).
- This energy source has an internal resistance \( r \).
- There is a load resistance \( R \) connected to the battery.

2. **Current Flow in the Circuit**:
- When the circuit is closed, a current \( I \) flows through the load and the internal resistance of the battery.
- According to Ohm's law, the total voltage in the circuit is equal to the sum of the voltage drops across the load and the internal resistance.

3. **Applying Ohm's Law**:
- The current \( I \) can be expressed as:
\[ I = \frac{E}{R + r} \]
- Here, \( R \) is the load resistance and \( r \) is the internal resistance of the energy source.

4. **Condition for Constant Current**:
- For the current \( I \) to remain constant, the total resistance in the circuit must not change with variations in load.
- This can be achieved if the internal resistance \( r \) is negligible compared to the load resistance \( R \).

5. **Analyzing the Options**:
- If \( r \) is very large compared to \( R \), the current would decrease significantly, which is not desirable.
- If \( r \) is equal to \( R \), the current would be half of what it could be, which is also not ideal.
- If \( r \) is non-zero but less than \( R \), the current would still vary with changes in \( R \).
- If \( r \) is zero, the equation simplifies to:
\[ I = \frac{E}{R} \]
which indicates a constant current regardless of the load.

6. **Conclusion**:
- The internal resistance of the energy source must be zero for it to supply a constant current into the load.

### Final Answer:
The internal resistance of the energy source should be **zero**.