A Level Physics Practice Exam

What is the charge of the nucleus?

1. Neutral charge

2. Positive charge

3. Negative charge

4. Variable charge

The correct answer is: Positive charge

The charge of the nucleus is positive due to the presence of protons, which are positively charged particles. In an atom, the nucleus contains protons and neutrons, while electrons orbit around the nucleus. Since neutrons carry no charge, the overall charge of the nucleus is determined solely by the protons. In essence, the number of protons in the nucleus defines the atomic number of an element, and this number dictates the element's identity. For instance, hydrogen has one proton and a positive charge, while helium has two protons and a charge that remains positive. This positive charge is essential for the attractive electrostatic force that holds electrons in orbit around the nucleus, balancing the overall atom's charge for most neutral atoms having an equal number of protons and electrons. The other options—neutral, negative, and variable charge—do not accurately describe the nature of the nucleus in standard atomic structure; thus, they do not reflect the fundamental principles of atomic physics as understood in A Level studies.