Which of the following is not deflected by magnetic field

Options

A. Deutrons
B. Positron
C. Proton
D. Photon

Explanation

To determine which of the following particles is not deflected by a magnetic field, we need to analyze the properties of each option provided.

1. **Deuteron**: A deuteron is the nucleus of deuterium, consisting of one proton and one neutron. Since it has a positive charge (due to the proton), it will be deflected by a magnetic field.

2. **Positron**: A positron is the antimatter counterpart of an electron, possessing a positive charge. Being charged, it will also be deflected by a magnetic field.

3. **Proton**: A proton is a positively charged particle. Like the deuteron and positron, it will also experience a deflection in a magnetic field due to its charge.

4. **Photon**: A photon is a massless particle that carries energy and does not possess any charge. Since it has no charge, it will not be deflected by a magnetic field.

Based on this analysis, the particle that is not deflected by a magnetic field is the **photon**.

**Final Answer**: The correct option is **photon**.

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