A charged oil droplet of mass m is falling, initially freely, in a vacuum between two horizontal metal plates that are separated by a distance x. A potential difference (p.d.) V is then applied across the plates. This results in the oil droplet continuing to accelerate downwards but with a reduced acceleration a. The polarity of the applied p.d. is then reversed so that the direction of the electric force on the droplet is reversed. This results in the downwards acceleration of the oil droplet increasing to 3a. What is the magnitude of the charge on the oil droplet?

A uniform electric field is produced between two parallel metal plates. The electric field strength is 1.4 × 10⁴ NC⁻¹…

Which row describes the circumstances under which forces act on a charged particle in a uniform electric field?

Two conducting layers of a liquid crystal display of a calculator are 8 µm apart. A 1.5V cell is connected across the…

Kirchhoff's second law is a consequence of a basic principle. What is this principle?

A proton in a nucleus undergoes β⁺ decay. One of the products is a neutron. What are the other products?

A certain type of hadron has zero charge. It is composed of a down quark, a strange quark and one other quark. What c…