Given a scientific passage and an answer, generate a question for the given answer.

Passage: Most metalloids have some physical properties of metals and some physical properties of nonmetals. They fall between metals and nonmetals in their ability to conduct heat and electricity. They are shiny like metals but brittle like nonmetals. All exist as solids at room temperature. Answer: silicon
What is an example of a metaloid element?

Passage: Dermal tissue covers the outside of a plant. It's like the plant's skin. Cells of dermal tissue secrete a waxy substance called cuticle. Cuticle helps prevent water loss and damage to the plant. Answer: cuticle
What do cells of dermal tissue secrete?

Passage: Most of us have at least one device in our homes that guards our safety and, at the same time, depends on radioactivity to operate properly. This device is a smoke detector. A typical smoke detector contains an electric circuit that includes two metal plates about 1 cm apart. A battery in the circuit creates a voltage between the plates. Next to the plates is a small disk containing a tiny amount (0.0002 g) of the radioactive element americium. The radioactivity of americium ionizes the air between the plates, causing a tiny current to. Answer: voltage
In a smoke detector, a battery in the electric circuit creates what between the metal plates?