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

Q: Passage: The energy in sunlight, or solar energy, can be used to heat homes. It can also be used to produce electricity in solar cells. However, solar energy may not be practical in areas that are often cloudy. Answer: solar energy

A: The energy in sunlight is also known as what kind of energy?
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Q: Passage: According to the cell theory , all living things are made up of cells, which is the structural unit of living organisms, and living cells always come from other living cells. In fact, each living thing begins life as a single cell. Some living things, such as bacteria, remain single-celled. Other living things, including plants and animals, grow and develop into many cells. Your own body is made up of an amazing 100 trillion cells! But even youlike all other living thingsbegan life as a single cell. Answer: trillions of cells

A: What is your body made up of?
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Q: Passage: Good conductors have large numbers of free charges in them. In metals, the free charges are free electrons. Figure 20.6 shows how free electrons move through an ordinary conductor. The distance that an individual electron can move between collisions with atoms or other electrons is quite small. The electron paths thus appear nearly random, like the motion of atoms in a gas. But there is an electric field in the conductor that causes the electrons to drift in the direction shown (opposite to the field, since they are negative). The drift velocity v d is the average velocity of the free charges. Drift velocity is quite small, since there are so many free charges. If we have an estimate of the density of free electrons in a conductor, we can calculate the drift velocity for a given current. The larger the density, the lower the velocity required for a given current. Answer: many free charges

A:
Why is the drift velocity negligible?
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