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Olympiad (Class 7) Electric current and its effects — practice questions — page 3

Explore 65 free Electric current and its effects questions in Olympiad (Class 7) Science. Open each question or exercise to read its content, reference answers and available explanation.

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Electric current and its effects questions and exercises with answers

Showing questions 61–65 of 65.

A flow of positive charge to the right has the same effect as an equal flow of negative charge moving:Read the answer and worked solution →Aluminium wire joints can heat up because aluminium readily forms an insulating:Read the answer and worked solution →Aluminium is preferred for long power lines mainly because it is:Read the answer and worked solution →The electric power delivered to homes is mostly:Read the answer and worked solution →Which of these is used as a transformer insulator?Read the answer and worked solution →

Worked practice questions

A flow of positive charge to the right has the same effect as an equal flow of negative charge moving:

  1. To the right
  2. Upward only
  3. To the left
  4. In circles
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Correct answer: C. To the left

Negative charge moving the opposite way gives the same current in the circuit.

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Aluminium wire joints can heat up because aluminium readily forms an insulating:

  1. Alloy
  2. Acid
  3. Salt
  4. Oxide
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Correct answer: D. Oxide

A thin insulating oxide layer on aluminium raises resistance at connections, so they heat.

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Aluminium is preferred for long power lines mainly because it is:

  1. Heavier than copper
  2. Light and cheaper
  3. A better insulator
  4. Costlier than gold
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Correct answer: B. Light and cheaper

Aluminium costs about a third as much as copper by weight and is lighter, which suits long lines.

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