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11.7 - Exercises

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Introduction to Conductors

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Teacher
Teacher

Today, we'll discuss conductors and insulators. Can anyone tell me what they are?

Student 1
Student 1

I think conductors are materials that allow electricity to pass through them.

Teacher
Teacher

Exactly! And what about insulators?

Student 2
Student 2

Insulators do not allow electricity to flow.

Teacher
Teacher

Correct! Remember this acronym: CAN (Conductors Allow current, Non-conductors Halt current). Now, why do you think it’s dangerous to use electrical appliances with wet hands?

Student 3
Student 3

Because water is a good conductor, so electricity could flow through us easily.

Teacher
Teacher

Exactly, and that’s why safety is essential when dealing with electricity. Let’s summarize: conductors allow electrical current to pass. Now, let’s move on to testing liquids.

Testing Liquids for Conductivity

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Teacher
Teacher

We can test if liquids conduct electricity using a simple electric tester. Who can help me understand how we would set this up?

Student 4
Student 4

We need to dip the free ends of the tester into the liquid, right?

Teacher
Teacher

That’s right! We dip it in and see if the bulb glows or not. What does that tell us?

Student 1
Student 1

If it glows, the liquid conducts electricity.

Teacher
Teacher

Perfect! Now, let’s remember: LACE (Lemon juice And Conductive Electricity). Let’s look at some examples. What liquids do you think will conduct?

Student 2
Student 2

Lemon juice, vinegar, and salt water should conduct because they are solutions.

Teacher
Teacher

Great observations! Now, who can tell me what we expect from distilled water?

Student 3
Student 3

It should not conduct unless we add salt to it.

Teacher
Teacher

Exactly! Let’s test our liquids.

Chemical Reactions from Electric Current

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Teacher
Teacher

When electric current flows through a conducting solution, what happens?

Student 4
Student 4

I think it can cause bubbles and change the solution.

Student 1
Student 1

Right! It can also create gas bubbles!

Teacher
Teacher

Correct! This is due to the chemical reaction taking place. Remember to think of the acronym GACE (Gas And Color Effects). What is the significance of these reactions?

Student 2
Student 2

It shows the electric current can cause changes in materials, and it's useful in things like electroplating!

Teacher
Teacher

Exactly! Let's quickly recap: passing current through a solution can produce gas and change colors. Now, let’s discuss practical applications.

Applications of Electric Current

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Teacher
Teacher

Who knows what electroplating is?

Student 3
Student 3

It's when a layer of metal is deposited onto another metal!

Teacher
Teacher

Right! This process helps improve durability and appearance. Think DESS (Durable External Shiny Surface). Can anyone give me an example of where this is used?

Student 4
Student 4

Jewelry! They coat cheaper metals with gold to make them look valuable.

Teacher
Teacher

Exactly! Any other areas?

Student 1
Student 1

How about corrosion protection for iron by coating it with zinc?

Teacher
Teacher

Perfect! Let's summarize: electroplating is useful for both aesthetic and protective purposes in everyday items.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section covers the chemical effects of electric current and explores the conduction properties of different liquids.

Standard

In this section, the text discusses how electric current interacts with various materials, particularly focusing on liquids. It examines how some liquids are good conductors of electricity, while others are poor conductors, using various experiments and activities as examples.

Detailed

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Audio Book

Dive deep into the subject with an immersive audiobook experience.

Fill in the Blanks

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1.Fill in the blanks.
(a)Most liquids that conduct electricity are solutions of , ___ and .
(b)The passage of an electric current through a solution causes ___ effects.
(c)If you pass current through copper sulphate solution, copper gets deposited on the plate connected to the ___ terminal of the battery.
(d)The process of depositing a layer of any desired metal on another material by means of electricity is called ___.

Detailed Explanation

In this section, you are tasked with filling in the blanks related to electric current and its effects. Each blank corresponds to key concepts recently discussed in the text, such as the importance of solutions of acids, bases, and salts in conducting electricity. Understanding that electric current has chemical effects is crucial for comprehending how electricity interacts with materials.

Examples & Analogies

Think of filling out a crossword puzzle where each word relates to something you've learned. Just as you remember specific words to complete the puzzle, these answers are foundational knowledge you build upon in the study of electricity.

Understanding Magnetic Deflection

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2.When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

Detailed Explanation

When the tester's ends are submerged in an electrically conductive solution, an electric current flows through it. This current generates a magnetic field, which affects the nearby compass needle, causing it to deflect. This demonstrates the relationship between electricity and magnetism, which is an important principle in physics.

Examples & Analogies

Imagine using a metal detector at the beach. The metal detector creates a magnetic field, and when it comes close to any metal, it beeps. Similarly, your tester's current creates a magnetic effect that turns the compass needle, which is its way of 'beeping' about the presence of electricity.

Identifying Conducting Liquids

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3.Name three liquids, which when tested in the manner shown in Fig.11.9, may cause the magnetic needle to deflect.

Detailed Explanation

To answer this, one must recall that good conductors of electricity, such as saltwater, vinegar, and lemon juice, enable electric current to flow. When these are tested using the previously explained method, the electric current's magnetic effects will make the compass needle deflect, showing that these liquids can conduct electricity.

Examples & Analogies

Think about how different substances behave in water. Just as salt dissolves to enhance flavor in food and creates 'saltwater,' observe how certain liquids allow electricity to flow, making your tester react. The liquids you select act like the 'enthusiastic friends' stimulating the current!

Exploring Non-Conductivity

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4.The bulb does not glow in the setup shown in Fig.11.10. List the possible reasons. Explain your answer.

Detailed Explanation

When a bulb connected to a circuit does not glow, it usually indicates that the electric current cannot flow through the circuit. Possible reasons could be a broken connection, the absence of a conductive path, or the bulb being faulty. Understanding these conditions is crucial for troubleshooting electrical circuits.

Examples & Analogies

Think of a water hose: if there is a kink in the hose or if the water supply is turned off, water will not flow through it, just like electricity needs a continuous path to flow and light the bulb.

Comparing Liquid Conductivity

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5.A tester is used to check the conduction of electricity through two liquids, labelled A and B. It is found that the bulb of the tester glows brightly for liquid A while it glows very dimly for liquid B. You would conclude that (i) liquid A is a better conductor than liquid B. (ii) liquid B is a better conductor than liquid A. (iii) both liquids are equally conducting. (iv) conducting properties of liquid cannot be compared in this manner.

Detailed Explanation

The glowing brightness of a bulb in a tester indicates the strength of the current flowing through the circuit. If Liquid A allows for a bright glow and Liquid B a dim glow, it can be concluded that Liquid A is a better conductor. This helps in understanding the comparative conductivity of different liquids.

Examples & Analogies

Imagine testing two batteries by seeing which one makes a flashlight brighter. The brighter flashlight indicates the better battery, much like observing which liquid allows electricity to flow more effectively through the tester.

Testing Pure Water

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6.Does pure water conduct electricity? If not, what can we do to make it conducting?

Detailed Explanation

Pure water is not a good conductor of electricity because it lacks free ions. To make it conductive, salts like table salt can be dissolved in it. This adds ions that facilitate electric current flow. Hence, understanding the composition of liquids is crucial in predicting their conductive properties.

Examples & Analogies

Think of pure water as a quiet road with no traffic. It’s hard for anything to move. Once you add salt, it’s like adding a lot of cars, allowing the traffic to flow freely.

Understanding Electrical Safety

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7.In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.

Detailed Explanation

Shutting off the electricity before using water hoses during a fire is a safety precaution. Water conducts electricity, and if there is a live electric current nearby, using water could lead to electrocution hazards. This is a vital knowledge for ensuring safety during emergencies.

Examples & Analogies

It’s akin to wearing a life jacket before entering the water—taking precautions to protect oneself from potential dangers. Similarly, firemen ensure there’s no risk of electric shock before using water to extinguish fires.

Understanding Seawater Conductivity

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8.A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?

Detailed Explanation

Seawater contains many dissolved salts, making it a better conductor of electricity compared to drinking water, which may have fewer dissolved ions. The deflection of the compass needle indicates a stronger electric current through the seawater, demonstrating how different water types can vary in conductivity.

Examples & Analogies

Think of drinking water as a small pond and seawater as the ocean. The ocean has much more 'wildlife' (dissolved minerals), so it supports a much 'livelier' current—just like seawater is more conductive.

Assessing Safety During Rain

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9.Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.

Detailed Explanation

It is not safe for electricians to work outdoors during heavy rain because the wet environment significantly increases the risk of electric shock. Water is a conductor of electricity, and in case of a fault in the electric system, this could lead to a serious accident. Electricians must prioritize safety in such conditions.

Examples & Analogies

It’s like trying to swim during a thunderstorm; it’s not just about being in water but the danger of lightning. Just as we understand weather before swimming, electricians need to consider environmental conditions to prevent accidents.

Observations on Rainwater Conductivity

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10.Paheli had heard that rainwater is as good as distilled water. So she collected some rainwater in a clean glass tumbler and tested it using a tester. To her surprise she found that the compass needle showed deflection. What could be the reasons?

Detailed Explanation

Rainwater can pick up minerals and pollutants from the air and surfaces it falls on, making it potentially conductive. Hence, while it is less pure than distilled water, it can conduct electricity to some extent, which is why the compass needle showed deflection.

Examples & Analogies

Imagine rainwater like a sponge collecting everything it touches. While distilled water is pure and 'clean,' rainwater can soak up whatever it lands on, making it sometimes conductive, much like how sponges can be both clean or dirty depending on what they absorb.

Listing Electroplated Objects

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11.Prepare a list of objects around you that are electroplated.

Detailed Explanation

Electroplating can be found in many everyday objects, such as jewelry, cutlery, and vehicle components. This process adds a layer of a more desirable metal to enhance attributes like appearance, corrosion resistance, or conductivity. Understanding the use of electroplating is essential in identifying and appreciating various applications in our lives.

Examples & Analogies

Think of how a wrapper enhances a candy's appeal while protecting it. Electroplating works similarly—to make items look better and last longer without changing their core material.

Understanding Electrolysis for Purification

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12.The process that you saw in Activity 11.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from the impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?

Detailed Explanation

In the electrolysis activity, the impure copper rod should be connected to the positive terminal. The positive electrode attracts negatively charged copper ions from the solution, causing pure copper to deposit on the thin plate. Understanding this concept is crucial in grasping how impurities can be removed, yielding purer metals.

Examples & Analogies

Imagine a magnet attracting iron filings. In this case, the positive electrode effectively attracts copper ions, pulling them 'closer' and depositing them where they are needed, successfully cleaning and refining the metal.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Conductors vs Insulators: Conductors allow electricity, while insulators do not.

  • Testing Liquid Conductivity: Liquids can be tested for conductivity using a simple electric tester.

  • Chemical Effects of Current: Passing current through solutions can lead to chemical reactions, such as gas production.

  • Electroplating: The process of depositing a layer of metal onto another material through electrical means.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • Lemon juice conducts electricity, which is why it glows a tester bulb.

  • Water may not conduct electricity, but adding salt makes it a conductor.

  • Electroplating is used to coat iron with zinc to prevent corrosion.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • Lemon juice and vinegar too, conduct electricity, it's true!

📖 Fascinating Stories

  • Once a lemon and a banana wanted to race in a circuit. The lemon glowed bright with electricity, showing it was a good conductor, while the banana stood still, knowing it couldn't pass the tests of the current.

🧠 Other Memory Gems

  • GACE: Gas And Color Effects for the changes we see when current flows.

🎯 Super Acronyms

DESS

  • Durable External Shiny Surface reminds us electroplating provides protective coatings.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Conductors

    Definition:

    Materials that allow electric current to flow through them easily.

  • Term: Insulators

    Definition:

    Materials that do not allow electric current to flow through them.

  • Term: Electroplating

    Definition:

    The process of depositing a layer of metal onto another material using electric current.

  • Term: Good Conductor

    Definition:

    A substance that allows electricity to pass through with minimal resistance.

  • Term: Poor Conductor

    Definition:

    A substance that does not allow electricity to pass through easily.

  • Term: Electrode

    Definition:

    The conductor through which electricity enters or leaves an electrolyte solution.