Đặt lần lượt các điện tích 1q 1nC  ; 2 q 1nC  ; 3q 1nC  ; 4q 1nC  vào các đỉnh A, B, C, D của hình chữ nhật, kích thước 20cm 40cm  trong không khí. Tính điện thế tại O là giao điểm của hai đường chéo hình chữ nhật, chọn gốc điện thế tại vô cùng.

Which sentence indicates that curium is a not a mineral? curium is a chemical element. it is a hard metal that looks like silver in light and glows red in the dark. it was first identified by american scientists working with nuclear energy during world war ii. the scientists, who included glenn seaborg, ralph james, and albert ghiorso, named the element after marie and pierre curie, nobel prize-winning scientists. they found that this human-made element is created when plutonium is bombarded with alpha-particles using a cyclotron. curium is a highly radioactive substance. it is extremely hazardous to human health. on entering the human body, it can hamper the production of red blood corpuscles and cause cancer. however, scientists continue to produce the element for its usefulness in scientific research. for example, it scientists understand the composition of rocks and soil on mars and can also be used to produce thermal energy. scientists have succeeded in producing many curium compounds, such as curium dioxide and curium chloride. these compounds are also used primarily in scientific research.