Given a scientific passage and an answer, generate a question for the given answer.
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Question: Passage: Chemical cells are found in batteries. They produce voltage by means of chemical reactions. Chemical cells have two electrodes, which are strips of different materials, such as zinc and carbon. The electrodes are suspended in an electrolyte. This is a substance that contains free ions, which can carry electric current. The electrolyte may be either a paste, in which case the cell is called a dry cell, or a liquid, in which case the cell is called a wet cell. Flashlight batteries contain dry cells. Car batteries contain wet cells. Answer: chemical

Answer: Batteries produce voltage through what type of reaction?

Question: Passage: Soil is a precious resource. It allows us to grow food and the materials we use to make everything from the shirt you have on to the medicine you took this morning. Soil is made up of small pieces of rock that have broken down over hundreds, if not thousands, of years. Soil is also partly made up of the remains of plants and animals, and is home to many organisms, from earthworms to ants. But soil can be damaged by unsustainable farming practices and clear-cut logging. In this chapter, you will learn how soil forms, what it contains, and how to protect it. Answer: soil

Answer: What precious resource allows us to grow food as well as materials we turn into clothing and medicine?

Question: Passage: As you can see in Figure above , a transformer consists of two wire coils wrapped around an iron core. When alternating primary current passes through coil P, it magnetizes the iron core. Because the current is alternating, the magnetic field of the iron core keeps reversing. This changing magnetic field induces alternating current in coil S, which is part of another circuit. In Figure above , coil P and coil S have the same number of turns of wire. In this case, the voltages of the primary and secondary currents are the same. However, when the two coils have different numbers of turns, the voltage of the secondary current is different than the voltage of the primary current. Both cases are illustrated in Figure below . Answer: magnetizes it

Answer:
When alternating primary current passes through coil p, it does what to the iron core?