Electricity: Magnetic and Heating Effects Class 8 Worksheet with Answers Science Chapter 4 - #NCSOLVE 📚

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Class 8 Science Chapter 4 Electricity: Magnetic and Heating Effects Worksheet

Class 8 Electricity: Magnetic and Heating Effects Worksheet

Worksheet On Electricity: Magnetic and Heating Effects Class 8 – Electricity: Magnetic and Heating Effects Worksheet Class 8

A. Objective Type Questions

Multiple Choice Questions

Question 1.
Which material is used to make electromagnets stronger?
(a) Plastic
(b) Wood
(c) Iron
(d) Glass
Answer:
(c) Iron

Question 2.
In an electric heater, why is a coiled wire used instead of a straight wire for the heating element?
(a) To make it look more attractive
(b) To increase resistance and produce more heat
(c) To reduce the cost of manufacturing
(d) To make it easier to replace when broken
Answer:
(c) To reduce the cost of manufacturing

Question 3.
During a classroom demonstration, the teacher showed that a voltaic cell stops working
after some time because
(a) the metal electrodes get too hot
(b) the chemical get used up
(c) the wires become loose over time
(d) the plastic container develops cracks
Answer:
(b) the chemical get used up

Question 4.
When comparing dry cells and rechargeable batteries, which statement’s correct?
(a) Dry cells can be reused multiple times like rechargeable batteries
(b) Rechargeable batteries are cheaper in the long run than dry cells
(c) Both work exactly on the same principle
(d) Dry cells are more environmentally friendly than rechargeable ones
Answer:
(b) Rechargeable batteries are cheaper in the long run than dry cells

Question 5.
Why do engineers use electromagnets in scrap yards instead of permanent magnets?
(a) Because permanent magnets are too expensive
(b) Because electromagnets can be switched on/off when needed
(c) Because permanent magnets don’t attract iron
(d) Because electromagnets work without electricity
Answer:
(b) Because electromagnets can be switched on/off when needed

Question 6.
What precaution should be taken when disposing of used batteries from household devices?
(a) Throw them in regular trash for easy disposal
(b) Burn them to destroy harmful chemicals
(c) Recycle them through proper e-waste channels
(d) Bury them in the backyard
Answer:
(b) Burn them to destroy harmful chemicals

Question 7.
What is the primary reason for using nichrome rather than copper in electric heating devices?
(a) Nichrome is much cheaper than copper
(b) Nichrome has higher electrical resistance
(c) Nichrome doesn’t conduct electricity
(d) Nichrome changes colour when heated
Answer:
(c) Nichrome doesn’t conduct electricity

Question 8.
In an electric circuit, if we keep increasing the current through a wire, what eventually happens?
(a) The wire becomes superconducting
(b) The wire’s resistance decreases automatically
(c) The wire may overheat and get damaged
(d) The wire starts producing light
Answer:
(b) The wire’s resistance decreases automatically

Question 9.
Why are lithium-ion batteries preferred for modern electric vehicles?
(a) Because they are the heaviest type of battery
(b) Because they can store more energy for their size
(c) Because they cannot be recharged
(d) Because they work best in cold weather
Answer:
(d) Because they work best in cold weather

Question 10.
What important function does the Earth’s magnetic field serve for livh^g.ar§anisms?
(a) It helps regulate the Earth’s temperature
(b) It protects from harmful solar radiation
(c) It makes compasses point randomly
(d) It increases atmospheric pressure
Answer:
(b) It protects from harmful solar radiation

Question 11.
If Earth’s magnetic field suddenly disappeared, which technological system would be affected most immediately?
(a) Satellite communications
(b) Compass-based navigation
(c) Cyclone prediction systems
(d) Electromagnets
Answer:
(b) Compass-based navigation

Question 12.
In the figure, a straight vertical wire is carrying current I and a magnetic compass is placed near it. The compass needle is observed to deflect to the right.

What does this deflection of the compass needle indicate?
(a) The wire has no magnetic effect
(b) The compass is faulty
(c) The magnetic field is present around the wire
(d) The current is flowing downward
Answer:
(c) The magnetic field is present around the wire

Question 13.
In the figure, two wires — Wire A and Wire B — are made of the same material and connected to identical batteries. Both are used as heating elements.

Which wire will get hotter and why?
(a) Wire B, because it allows more current to flow
(b) Wire B, because it has more resistance
(c) Both will get equally hot
(d) Wire A, because it has higher resistance
Answer:
(b) Wire B, because it has more resistance

Assertion-Reason Questions And Answers

The questions given below consist of an Assertion and a Reason. Based on that, choose the appropriate option.
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.

Question 1.
Assertion: An electromagnet can lift heavier iron objects when more turns are added to its coil.
Reason: Increasing coil turns strengthens the magnetic field for the same current.
Answer:
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Question 2.
Assertion: An electromagnet used in cranes can lift heavy scrap metal only when the electric current is flowing through it.
Reason: Electric current produces a magnetic field that disappears when the current is switched off.
Answer:
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Question 3.
Assertion: An iron nail placed inside a coil has no effect on the coil’s magnetic strength.
Reason: Iron is a soft magnetic material that enhances the magnetic field inside a coil.
Answer:
(d) Assertion is false, but reason is true,
an iron nail placed inside a coil increases the magnetic strength of the coil.

Question 4.
Assertion: A permanent magnet is preferred an electromagnet in a scrapyard crane.
Reason: Electromagnets lose their magnetic field when the electric supply is cut off.
Answer:
(d) Reason is true, but the assertion is false,
electromagnets are preferred in a scrapyard crane because one can control its magnetic effects by controlling electric supply.

Question 5.
Assertion: NichrOme is widely used in electric wires for household wiring.
Reason: Nichrome has higher resistance than copper and does not melt easily.
Answer:
(d) Assertion is false, but Reason is true.
Nichrome is not used in household wiring but copper is, due to its low resistance.

Flow Chart Completion
Complete the flowchart showing the steps of an activity to observe the magnetic effect of electric current.

Steps to Choose From Wrap insulated copper wire around an iron nail Collect materials like battery, wire, nail, and clips Observe if paper clips stick to the nail Bring nail near some iron paper clips

Answer:
(a) Collect materials like battery, wire, nail, and clips
(b) Wrap insulated copper wire around an iron nail
(c) Bring nail near some iron paper clips
(d) Observe if paper clips stick to the nail

Fill in the Blanks

Question 1.
Fill in the blanks by choosing the appropriate words from the box below:

electromagnet, current, magnetic, compass, heating, iron, rechargeable, coil, paste, dry cell

(a) The magnetic strength of an electromagnet increases if an ______________ core is placed inside the ______________.
Answer:
iron, coil

(b) A strong ______________ is used in cranes to lift scrap metal easily.
Answer:
electromagnet

(c) A ______________ is used to detect the direction of a magnetic field.
Answer:
compass

(d) A ______________ contains a zinc case and a carbon rod with an electrolyte in the form of a moist ______________.
Answer:
dry cell, paste

(e) ______________, batteries are better for the environment as they reduce waste.
Answer:
rechargeable

Question 2.
Fill in the blanks by unjumbling the words given in the bracket:
(a) The flow of electric ______________ (curnrte) can produce both heat and magnetism.
Answer:
current

(b) Hans Christian ______________ (deterso) discovered the magnetic effect of current.
Answer:
orested

(c) Devices like electric irons and kettles work on the ______________ (inatehg) effect of electric current
Answer:
heating

(d) The moist paste in a dry cell acts as an ______________(lretceolyte).
Answer:
electrolyte

(e) When many lemons are connected together, they form a simple ______________ (yrtabte).
Answer:
battery

True/False

Question 1.
Put a tick (✓) with a green sketch pen for correct statements and a cross (✗) with a red sketch pen for incorrect ones.
(a) Hans Christian Oersted discovered the connection between electricity and magnetism.
Answer:
✓

(b) Earth’s magnetic field helps migratory birds find their way.
Answer:
✓

(c) An electric bell uses the heating effect of current to produce sound.
Answer:
✗, An electric bell works on the magentic effect of electric current, not the heating effect.

(d) A voltaic cell uses two identical metal plates as electrodes.
Answer:
✗, A voltaic cell uses two different metals like zinc and copper as electrodes.

(e) A dry cell uses lemon juice as its electrolyte.
Answer:
✗, A dry cell uses a thick moist paste as electrolyte.

Question 2.
Choose the option which shows the correct sequence of True (T) and False (F) for the statements given below.
(a) The Earth’s magnetic field protects us from harmful solar radiation.
(b) Electric irons use the magnetic effect of current.
(c) Recycling batteries harms the environment.
(d) Damaged wires should be used to save money.
(e) The carbon rod in a dry cell is the positive terminal.
(1) T F F F T
(2) F T T F F
(3) T T F T F
(4) F F T T T
Answer:
(1) T F F F T

Match the Following

Question 1.
Match the terms in Column I with their related explanations in the Column II.

Column I	Column II
(a) Electromagnet	(i) Produces heat when current flows
(b) Dry cell	(ii) Points north south
(c) Nichrome wire	(iii) Works only when current flows
(d) Compass	(iv) Used in remotes and clocks
(e) Heating effect of current	(v) Zinc container and carbon rod
(f) Structure of a dry cell	(vi) Converts electric energy to heat

Answer:

Column I	Column II
(a) Electromagnet	(iii) Works only when current flows
(b) Dry cell	(iv) Used in remotes and clocks
(c) Nichrome wire	(i) Produces heat when current flows
(d) Compass	(ii) Points north south
(e) Heating effect of current	(vi) Converts electric energy to heat
(f) Structure of a dry cell	(v) Zinc container and carbon rod

Question 2.
Look at the pictures given below carefully. Each picture shows a device or activity related to the effects of electric current.
Classify the pictures into the following two categories:

Magnetic Effect of Current, Heating Effect of Current

Answer:
(a) Heating effect of current.
(b) Magnetic effect of current.
(c) Magnetic effect of current.
(d) Heating effect of current.
(e) Magnetic effect of current.
(f) Heating effect of current.
(g) Heating effect of current.

B. Subjective Type Questions

Define the Following Terms

Question 1.
Magnetic effect of current
_________________________________

Question 2.
Electromagnet
_________________________________

Question 3.
Heating element
_________________________________

Question 4.
Electrolyte
_________________________________

Question 5.
Rechargeable batteries
_________________________________

Give the Reason of the Following

Question 1.
Overheating in household circuits can cause fires.
_________________________________

Question 2.
Electric furnaces are used in steel manufacturing industries.
_________________________________

Question 3.
Voltaic cells use two different metals as electrodes.
_________________________________

Question 4.
Lithium-ion batteries are preferred for electric vehicles.
_________________________________

Question 5.
Scientists are developing new battery technologies.
_________________________________

Very Short Answer Type Questions

Question 1.
Name two household components that can be damaged due to excessive heating.
_________________________________
_________________________________

Question 2.
List any two factors that affect the amount of heat generated in a wire.
_________________________________
_________________________________

Question 3.
What type of metal wires produce more heat due to higher resistance?
_________________________________
_________________________________

Question 4.
Why should we use properly rated wires in electric circuits?
_________________________________
_________________________________

Question 5.
What problem occurs in wires if they overheat during electricity transmission?
_________________________________
_________________________________

Question 6.
Which two metals are commonly used as electrodes in voltaic cells?
_________________________________
_________________________________

Question 7.
Give one environmental benefit of battery recycling.
_________________________________
_________________________________

Question 8.
Name two metals used in lithium-ion batteries.
_________________________________
_________________________________

Question 9.
Why are countries focusing on recycling lithium-ion batteries?
_________________________________
_________________________________

Short Answer Type Questions

Question 1.
What is the relationship between electricity and magnetism as observed in electromagnets, and how is this principle used in modem machines?
_________________________________
_________________________________

Question 2.
How do the poles of an electromagnet resemble those of a regular^m^gnet, and what does this tell us about the nature of electromagnets?
_________________________________
_________________________________

Question 3.
In what ways are electromagnets more useful than permanent magnets in industrial applications like lifting heavy scrap metals?
_________________________________
_________________________________

Question 4.
How does the heating effect of electric current work in household appliances, and which devices use this principle for their functioning?
_________________________________
_________________________________

Question 5.
Name any three pairs of metals that can be used in voltaic cells and explain their role briefly.
_________________________________
_________________________________

Question 6.
Observe the figure of a dry cell shown below and answer the following:

(a) Name the part that acts as the positive terminal of the dry cell.
(b) What is the role of the electrolyte in the dry cell?
(c) Which part of the cell gets consumed slowly during the chemical reaction and acts as the negative terminal? .
_________________________________
_________________________________

Question 7.
How are lithium-ion batteries useful in modern life, and why is there a growing emphasis on recycling them globally?
_________________________________
_________________________________

Question 8.
How do scientists plan to solve the limited availability problem of metals like lithium and cobalt?
_________________________________
_________________________________

Long Answer Type Questions

Question 1.
Observe the given image and answer the following questions in detail.

(a) What is shown in the image?
_________________________________
_________________________________

(b) Which effect of electric current is being used here?
_________________________________
_________________________________

(c) Explain how the device shown in the image works?
_________________________________
_________________________________

Question 2.
Explain the working of an electric iron. What principle does it use? Why is nichrome used in its heating element? Also, list any two safety precautions to be followed while using such heating appliances.
_________________________________
_________________________________

Question 3.
(a) What is voltaic cell ? Explain its working briefly.
_________________________________
_________________________________

(b) Label the arrows marked in the diagram.

(A) ______________
(B) ______________
(C) ______________
(D) ______________
(E) ______________
(F) ______________

(c) Why does the electric bulb glow in this setup? What does it indicate about the liquid in the container?
_________________________________
_________________________________

Question 4.
In the diagram below, five lemons are connected in series using copper strips and iron nails. The combined voltage is enough to light up a small LED. Now, lemons are removed one by one from the series circuit.

Answer the following questions :
(a) What change do you observe in the LED as lemons are removed one by one? Explain why this happens ?
_________________________________
_________________________________

(b) What does this activity teach you about the importance of combining multiple lemons in a circuit?
_________________________________
_________________________________

Case Based Questions

Question 1.
Priya noticed smoke from her room’s wiring when too many appliances were used together. Her father replaced the thin wires with thicker ones, and the issue stopped. Why did thicker wires help?
(a) They have higher resistance
(b) They reduce overheating by lowering resistance
(c) They glow brighter
(d) They store extra electricity
Answer:
(b) They reduce overheating by lowering resistance

Question 2.
Read the paragraph and answer the following questions:
X is a device or component used in electric appliances like heaters, toasters, and geysers. When current passes through it, it gets hot and produces heat. It is made of special materials that have high resistance and can tolerate high temperatures without melting. One such material is T’, which is commonly used in making X because of its properties like high melting point and resistance.
I. What is X?
(a) Magnetic coil
(b) Heating element
(c) Electric wire
(d) Electromagnet
Answer:
(b) Heating element

II. What is T?
(a) Copper
(b) Aluminium
(c) Nichrome
(d) Plastic
Answer:
(c) Nichrome

Question 3.
A school collected used batteries in green bins labelled “E-Waste Only.” The teacher explained how these batteries contain toxic metals but can be recycled? Why is battery recycling important? .
(a) To extract harmful chemicals safely
(b) To make batteries glow brighter
(c) To increase their voltage
(d) To convert them into permanent magnets
Answer:
(a) To extract harmful chemicals safely

Question 4.
Riya: Hey Aman! I saw your science experiment at the exhibition. That electromagnet setup was amazing!
Aman: Thanks! I used an iron nail and wrapped copper wire around it. When I connected it to a battery, it picked up paper clips.
Riya: That’s so cool! But what happens when you switch off the current?
Aman: Then it stops attracting the clips. That’s the best part — you can turn the magnetism on and off.
Riya: I want to try it too. What wire did you use?
Aman: I used insulated copper wire, and made sure the nail was made of soft iron.
(a) What materials did Aman use to make the electromagnet?
_________________________________
_________________________________

(b) What happens to the electromagnet when the electric current is switched off ?
_________________________________
_________________________________

(c) What is the role of the iron nail in the electromagnet setup?
_________________________________
_________________________________

Skill Based Activities

Question 1.
Word Scramble Puzzle
A. Unscramble the jumbled words and fill the boxes.

Answer:
(i) IRON
(ii) ELECTROMAGNET
(iii) HEATING
(iv) VOLTAIC
(v) CELL
(vi) BATTERY

B. Using the circled letters from each jumbled word, and rearrange them to form a new word.
Hint: It is something that uses lithium-ion batteries to run.
New Word _________________________________
Answer:
VEHICLE

Question 2.
Classify the Objects
Below list of objects is given. Some of them work on the heating effect of electric current, while others use the magnetic effect.
Read the names carefully and classify them into the correct groups.

Object List

• Electric iron
• Electric bell
• Hair dryer
• Electromagnet crane
• Geyser
• Loudspeaker
• Room heater
• Electric motor
• Toaster
• Magnetic door lock

Heating Effect of Electric Current:	Magnetic Effect of Electric-Currrent
(i) ______________	(i) ______________
(ii) ______________	(ii) ______________
(iii) ______________	(iii) ______________
(iv) ______________	(iv) ______________
(v) ______________	(v) ______________

Answer:
Heating Effect of Electric Current:
(i) Electric iron
(ii) Hair dryer
(iii) Geyser
(iv) Toaster
(v) Room heater

Magnetic Effect of Electric Current:
(i) Electric bell
(ii) Electromagnet crane
(iii) Loudspeaker
(iv) Electric motor
(v) Magnetic door lock

Question 3.
Complete the Paragraph.
A dry cell converts ______________ (i) ______________ energy into electrical energy. It consists of a ______________ (ii) ______________ container that acts as the negative terminal, while a ______________ (iii) ______________ rod in the center serves as the positive terminal. The space between them is filled with a ______________ (iv) ______________ electrolyte paste. When connected in a circuit, ______________ (v) ______________ flows from the positive to the negative terminal.
Answer:
(i) chemical
(ii) zinc
(iii) carbon
(iv) moist
(v) current

Question 4.
From the word puzzle given below find atleast 8 words which are related to the chapter.

Answer:
Battery, Iron, Cell, Current, Heat, Magnet, Zinc, Compass.

The post Electricity: Magnetic and Heating Effects Class 8 Worksheet with Answers Science Chapter 4 appeared first on Learn CBSE.

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