Length of a wire
Lesson 5 / 9
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Waxaan sharxi karaa sababta fiilooyinka dhaadheer ay u leeyihiin iska caabin ka sarraysa fiilooyinka gaagaaban.
Introduction
In this lesson: I can explain why longer wires have a higher resistance than shorter wires. The longer a wire, the greater its resistance. Electric current in a wire is a flow of electrons moving through the spaces between ‘atoms’ (metal ions).
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Quizzes
1. Which of the following particles are the moving charges in a metal?
- protons
- neutrons
- gravitons
- Correct answer:electrons
2. Which of the following statements explain what happens if a bare copper wire is folded in half and doubled back on itself?
- Correct answer:The cross–sectional area doubles.
- The cross–sectional area halves.
- Correct answer:The current it can carry will double.
- Its resistance will double.
3. Which of the following statements explain what we mean when we say two variables are proportional?
- Correct answer:One variable changes as a multiple of the other one.
- If one variable increases, the other one decreases.
- If one variable increases, the other one remains constant.
- Both variables stay the same if the other one changes.
4. Which of the following statements describe the role of the plastic insulation around the copper wires in the cable shown?
- Correct answer:To stop the metal wires touching each other.
- Correct answer:To protect us from electrical shocks.
- Correct answer:To help us identify the wires.
- To make the wires look nicer.
5. The two wires shown are made from the same material. Which of the following resistances is the resistance of the thin wire?
- $${1\over2} \Omega$$
- 1 $$\Omega$$
- 4 $$\Omega$$
- Correct answer:8 $$\Omega$$
6. A wire with a cross–sectional area of 1 mm$$^2$$ allows a current of 0.2 A to flow through it. What current will flow in a wire of the same material with a cross–sectional area of 4 mm$$^2$$?
- 0.2 A
- 0.4 A
- Correct answer:0.8 A
- 1.6 A
1. Which of the following statements describes the cause of resistance in metal wires?
- Electrons in the wire repel each other.
- Electrons in the wire are attracted by atoms.
- Correct answer:Electrons in the wire collide with metal ions.
- Electrons in the wire collide with the sides of the wire.
2. The image shown is a representation of the arrangment of the particles in a metal. Which of the following particles do the black spheres represent?
- electrons
- protons
- neutrons
- Correct answer:metal ions
3. A metal wire has a resistance of 6 $$\Omega$$. Which of the following resistances is the new resistance of the wire if its length is increased by three times?
- 2 $$\Omega$$
- 3 $$\Omega$$
- 6 $$\Omega$$
- 12 $$\Omega$$
- Correct answer:18 $$\Omega$$
4. Which of the following resistances is the total resistance of the combination of resistors shown?
- 1 $$\Omega$$
- 2 $$\Omega$$
- 3 $$\Omega$$
- 4 $$\Omega$$
- Correct answer:7 $$\Omega$$
5. A current of 0.4 A flows through a resistance cable which is 12 m long. What current will flow through 3 m of the same resistance cable?
- 0.1 A
- 0.2 A
- 0.4 A
- 0.8 A
- Correct answer:1.6 A
6. The cross–sectional area of a wire is doubled and the length is halved. Which of the following statements describes what will happen to the resistance of the wire?
- The resistance halves.
- Correct answer:The resistance stays the same.
- The resistance doubles.
- The resistance increases by a factor of four.
What pupils see
The same lesson as a pupil sees it. You can set any section as work on its own.
- IntroductionPrepare
- Starter quizActivate · 6 questions
- Lesson videoLearn
- Exit quizCheck · 6 questions