Question

When a fast electron passes near a highly positively charged nucleus, x-rays are seen to get radiated. What could be the cause for this radiation?

• A. All interactions between two charged particles result in radiation of energy
• B. The nucleus deflects the electron inwards, giving it a centripetal acceleration, which causes the radiation from the charged electron
• C. The nucleus speeds the electron up, giving rise to radiation from an accelerated charge
• D. The radiation comes from the nucleus because of the change in its energy due to the electron.

Answer 1

The correct option is B The nucleus deflects the electron inwards, giving it a centripetal acceleration, which causes the radiation from the charged electron

A highly positive nucleus is one with a lot of protons in it. Molybdenum, which is used often in Coolidge tubes, has 42 protons in the nucleus. This amount of positive charge is enough to deflect super-fast electrons passing by.

This deflection gives an electron a centripetal acceleration, which results in radiation. If the nucleus is positive enough, the acceleration caused will be very high too, leading to a massive loss of the electron's kinetic energy - resulting in x-ray radiation.