Which one of the following statements concerning photons is false?

Options

A. Photons have zero mass
B. The rest energy of all photons is zero
C. Photons travel at the speed of light in a vacuum
D. Photons have been brought to rest by applying a strong magnetic field to them.

Answer

To determine which statement concerning photons is false, we will analyze each option provided in the question step by step.

### Step 1: Analyze the first statement - "Photons have zero mass."
- Photons are indeed massless particles. They have zero rest mass. This statement is **true**.

### Step 2: Analyze the second statement - "The rest energy of all photons is zero."
- The rest energy of a particle is given by the equation \(E_0 = mc^2\), where \(m\) is the rest mass. Since photons have zero rest mass, their rest energy is also zero. This statement is **true**.

### Step 3: Analyze the third statement - "Photons travel at the speed of light in vacuum."
- By definition, photons are particles of light and they travel at the speed of light in a vacuum, which is approximately \(3 \times 10^8\) m/s. This statement is **true**.

### Step 4: Analyze the fourth statement - "Photons have been brought to rest by applying a strong magnetic field to them."
- Photons do not have mass and do not interact with magnetic fields in a way that would allow them to be brought to rest. They always travel at the speed of light in a vacuum. This statement is **false**.

### Conclusion:
The false statement concerning photons is: "Photons have been brought to rest by applying a strong magnetic field to them."

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