Samacheer Kalvi 8th Science Book Back Answers Chapter 7

Samacheer Kalvi 8th Science Book Back Question and Answers:

Samacheer Kalvi 8th Standard Science Book Back 1 Mark and 2 Mark Question & Answers PDF uploaded and available below. Class 8 New Syllabus 2022 to 2023 Book Back Questions & Answers/solutions available for both English and Tamil Medium. Class 8 std Science Book Chapter 7 – Magnetism Answers/Solutions Guide are uploaded on this page. 8th standard Science Book is consists of 23 Units. All 23 chapters of Science Book Back One, and Two Mark Solutions are given below.

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8th Science Book Back Chapter 7 Solutions Guide PDF:

Samacheer Kalvi 8th Science Subject 1 Mark and 2 Mark Solutions Guide PDF available below. Click the Download option to download the book back 1 Mark & 2 Mark questions and answers. Take the printout and use it for exam purposes.

8th Science Chapter- 7

Magnetism – Book Back Answers

I. Choose the best answer:

1. A magnet attracts ………………
(a) wooden materials
(b) any metal
(c) copper
(d) iron and steel
Answer: (d) iron and steel

2. One of the following is an example for a permanent magnet.
(a) Electromagnet
(b) Mumetal
(c) Soft iron
(d) Neodymium
Answer: (d) Neodymium

3. The south pole of a bar magnet and the north pole of a U-shaped magnet will ……………….
(a) attract each other
(b) repel each other
(c) neither attract nor repel each other
(d) None of the above
Answer: (a) attract each other

4. The shape of the Earth’s magnetic field resembles that of an imaginary ………………
(a) U-shaped magnet
(b) straight conductor carrying current
(c) solenoid coil
(d) bar magnet
Answer: (d) bar magnet

5. MRI stands for………………
(a) Magnetic Running Image
(b) detection of magnetic field
(c) navigation
(d) Magnetic Radar Imaging
Answer: (a) Magnetic Resonance Imaging

6. A compass is used for ………………
(a) plotting magnetic lines
(b) detection of magnetic field
(c) navigation
(d) All of these
Answer: (d) All of these

II. Fill in the blanks:

The magnetic strength is …………… at the poles.
A magnet has …………… magnetic poles.
Magnets are used in …………… for generating electricity.
…………… are used to lift heavy iron pieces.
A freely suspended bar magnet is always pointing along the …………… north-south direction.

Answer:

maximum
two
dynamos
Electromagnets
geographic

III. Match the following:

Magnetite – Magnetic lines Natural
A tiny pivoted magnet – magnet
Cobalt – Compass box
Closed curves – Ferromagnetic material
Bismuth – Diamagnetic material

Answer:

Magnetite – Natural magnet
A tiny pivoted magnet – Compass box
Cobalt – Ferromagnetic material
Closed curves – Magnetic lines
Bismuth – Diamagnetic material

IV. Choose the correct option:

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.
(b) If both assertion and reason are true but the reason is not the correct explanation of assertion.
(c) If the assertion is true, but the reason is false.
(d) If the assertion is false, but the reason is true.

1. Assertion: Iron filings are concentrated more at the magnetic poles.
Reason: The magnets are so sharp.
Answer:
(b) Both assertion and reason are true but the reason is not the correct explanation of assertion.

2. Assertion: The Earth’s magnetic field is due to iron present in its core.
Reason: At a high temperature, a magnet loses its magnetic property or magnetism.
Answer:
(d) Assertion is false but the reason is true.

Correct statement:
The Earth’s magnetic field is due to the molten charged metallic fluid inside the Earth’s surface.