Can someone give me some pointers on calculating the rest energy of a positron (a particle that has the same mass as an electron and equal but opposite charge) ? thanks

The rest energy is equal to the mass times the speed of light squared.

To calculate the rest energy of a positron, you can use Einstein's famous equation: E = mc², where E represents energy, m represents mass, and c represents the speed of light.

In this case, since a positron has the same mass as an electron, you can use the known mass of an electron, which is approximately 9.10938356 × 10⁻³¹ kilograms. However, keep in mind that precision may vary depending on the level of accuracy required for your calculation.

Once you have the mass of the positron, multiply it by the square of the speed of light, which is approximately 299,792,458 meters per second. The square of the speed of light is approximately 8.987551793 × 10¹⁶ square meters per second squared.

So, the rest energy (E) of a positron can be calculated as follows:
E = (mass of positron) × (speed of light)²

To summarize, here are the steps to calculate the rest energy of a positron:

1. Obtain the mass of the positron (equal to the mass of an electron).
2. Square the speed of light.
3. Multiply the positron mass by the squared speed of light using the equation E = mc².
4. Calculate the result, which represents the rest energy of the positron.

Note: Make sure that you use a consistent unit for mass (such as kilograms) and convert units if necessary to ensure dimensional consistency when performing calculations.