Magnetic field lines determine

Options

A. The shape of magnetic field
B. Only the direction of magnetic field
C. Only the relative strength of the magnetic field
D. Both the direction and the relative strength of magnetic field

Explanation

To determine what magnetic field lines indicate, we can analyze the options provided in the question step by step.

### Step 1: Understanding Magnetic Field Lines
Magnetic field lines are visual representations of the magnetic field around a magnet. They show how the magnetic field behaves in space.

### Step 2: Direction of Magnetic Field
Magnetic field lines indicate the direction of the magnetic field. They emerge from the North Pole of a magnet and enter the South Pole. This means that the direction of the magnetic field is from North to South.

### Step 3: Relative Strength of Magnetic Field
The density of the magnetic field lines also indicates the strength of the magnetic field. Where the lines are closer together, the magnetic field is stronger. Conversely, where the lines are spaced further apart, the magnetic field is weaker.

### Step 4: Analyzing the Options
Now, let's analyze the options given in the question:
- **Option A**: The shape of the magnetic field - This is partially correct as the lines do show the shape.
- **Option B**: Only the direction of the magnetic field - This is not entirely correct since it also shows strength.
- **Option C**: Only the relative strength of the magnetic field - This is also not entirely correct since it shows direction too.
- **Option D**: Both the direction and the relative strength of the magnetic field - This is the most accurate option.

### Conclusion
Based on the analysis, the correct answer is **Option D**: Both the direction and the relative strength of the magnetic field.

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