New NCERT Science Chapter 1 Class 6 The Wonderful World of Science

 🌍 Human Body & Science Basics – Class 6 Notes | Vocabulary, MCQs & Q&A (NCERT/NCF 2023)

Class 6 Science Chapter 1 notes with important words, MCQs, and question answers?

Here is a complete, easy-to-understand guide based on NCF 2023 to help students learn quickly and revise effectively.

📘 Chapter: The Wonderful World of Science

Science is not just a subject—it is a way of thinking, observing, and understanding the world around us. It begins with curiosity and helps us explore everything from nature to daily life.

🔑 Important Keywords & Definitions

1. Science

Science is a way of thinking, observing, and understanding the world around us.

2. Curiosity

The desire to learn and ask questions.

3. Observation

Carefully watching and noticing things.

4. Question

A thought that arises when we want to know something.

5. Hypothesis

A possible guess or explanation.

6. Experiment

A test to check whether the hypothesis is correct.

7. Analysis

Studying results carefully.

8. Conclusion

The final answer after testing.

9. Scientific Method

A step-by-step process to solve problems:

Observation → Question → Hypothesis → Experiment → Analysis → Conclusion

10. Scientist

A person who follows the scientific method.

🧠 Multiple Choice Questions (MCQs)

1. Science is mainly a way of:

   a) Playing games b) Thinking and understanding c) Sleeping d) Drawing

   ✅ Answer: b

2. The first step of scientific method is:

   a) Conclusion b) Experiment c) Observation d) Analysis

   ✅ Answer: c

3. Curiosity means:

   a) Fear b) Anger c) Desire to know d) Laziness

   ✅ Answer: c

4. A hypothesis is:

   a) Final answer b) Guess c) Result d) Observation

   ✅ Answer: b

5. Which is NOT a step of scientific method?

   a) Observation b) Experiment c) Guess d) Sleeping

   ✅ Answer: d

6. Science helps us to:

   a) Ignore things b) Understand the world c) Forget things d) Sleep more

   ✅ Answer: b

7. Who can be a scientist?

   a) Only lab workers

   b) Only teachers

   c) Anyone who follows scientific method

   d) Only doctors

   ✅ Answer: c

8. Observation means:

   a) Guessing b) Watching carefully c) Writing d) Concluding

   ✅ Answer: b

9. Scientific knowledge:

   a) Never changes

   b) Always remains same

   c) Changes with discoveries

   d) Is fixed

   ✅ Answer: c

10. Science is like a:

    a) Game b) Puzzle c) Story d) Song

    ✅ Answer: b

QUESTIONS & ANSWERS

---

1. What is science? Explain with examples.

Answer:
Science is a way of understanding the world around us through observation, thinking, and experimentation. It helps us answer questions about nature, daily life, and the universe.

Science is not limited to books or laboratories. It is present in everything we do.

Examples:

• When we cook food, heat changes raw food into cooked food.

• When plants grow, they need sunlight, water, and air.

• When it rains, it is part of the water cycle.

Thus, science helps us understand both simple and complex phenomena in our surroundings.

---

2. Why is curiosity important in learning science?

Answer:
Curiosity is the desire to know and learn new things. It is the starting point of science.

When we are curious:

• We ask questions like Why, How, and What

• We try to explore and observe things carefully

• We attempt to find answers through thinking and testing

Without curiosity, learning becomes memorization. With curiosity, learning becomes interesting and meaningful.

For example, asking “Why do stars shine?” or “Why do plants grow?” leads to scientific discovery.

---

3. Explain the scientific method in detail with an example.

Answer:
The scientific method is a step-by-step process used to solve problems and find answers.

Steps:

1. Observation – Noticing something

2. Question – Asking why or how

3. Hypothesis – Making a possible guess

4. Experiment – Testing the guess

5. Analysis – Studying results

6. Conclusion – Final answer

Example: Pen stops writing

• Observation → Pen is not writing

• Question → Why is it not working?

• Hypothesis → Ink might be finished

• Experiment → Check refill

• Analysis → Ink is empty

• Conclusion → Pen stopped due to no ink

This shows how we use science in daily life situations.

---

4. How is science present everywhere in our daily life?

Answer:
Science is present in every aspect of our life—from nature to daily activities.

Examples:

• Cooking: Heat changes food (chemical change)

• Breathing: Oxygen is taken in, carbon dioxide is released

• Playing: Movement involves force and energy

• Weather: Rain, wind, and seasons are natural processes

• Household items: Plastic, metal, and wood are different materials

Thus, science is not limited to classrooms—it is all around us.

---

5. Why is science called a continuous and changing process?

Answer:
Science is called a continuous process because:

• New discoveries are made regularly

• Old ideas can change with new evidence

• Knowledge keeps improving over time

For example:
Earlier people believed the Earth was flat, but later discoveries proved it is spherical.

This shows that science is like a growing puzzle, where each discovery adds a new piece.

---

6. Who is a scientist? Can ordinary people be scientists? Explain.

Answer:
A scientist is a person who follows the scientific method to solve problems and discover new things.

Yes, ordinary people can also be scientists because:

• Anyone who observes, questions, and tests ideas is using science

Examples:

• A cook checking why food burned

• A mechanic fixing a bicycle

• A student solving a problem

Thus, science is not limited to laboratories—it is a skill anyone can use.

---

7. Explain the importance of observation in science.

Answer:
Observation is the first and most important step in science.

It helps us:

• Notice changes and patterns

• Identify problems

• Ask meaningful questions

Example:

If a plant is not growing well, observation helps us see:

• Is it getting enough sunlight?

• Is it watered properly?

Good observation leads to better understanding and correct conclusions.

---

8. How are different scientific ideas connected to each other?

Answer:
Scientific ideas are interconnected because:

• One concept often leads to another

• Different topics are related in real life

Examples:

• Plants need sunlight → linked to energy

• Water changes form → linked to temperature

• Food gives energy → linked to body functions

Thus, science is not separate topics—it is a connected system of knowledge.

---

9. Explain the role of teamwork in science.

Answer:
Science is rarely done alone. Scientists often work in teams.

Importance of teamwork:

• Sharing ideas improves understanding

• Different people bring different skills

• Problems can be solved faster

Example:

Large discoveries like space missions involve many scientists working together.

Thus, collaboration makes science more effective and interesting.

---

10. Why should we ask “WHY” in science? Explain.

Answer:
Asking “WHY” is important because:

• It leads to deeper understanding

• It develops critical thinking

• It helps in discovering new ideas

Example:

• Why does it rain?

• Why do objects fall?

Such questions lead to scientific explanations.

👉 A wise person is one who keeps asking questions and seeking answers.

---

🎯 BONUS REFLECTION QUESTION (NCF STYLE)

Q. Describe a situation where you used the scientific method in real life.
👉 Students can write their own experience (pen not working, plant not growing, etc.)

Unit 4: d- and f-Block Elements Chemistry Previous year questions PYQ

Unit 4: d- and f-Block Elements

Part A: d-Block Elements (Transition Metals)

1. General Introduction

The d-block elements are found in groups 3 to 12 of the periodic table. These elements have partially filled d-orbitals either in ground state or in one of their oxidation states.

2. Electronic Configuration

The general configuration of d-block elements is:

[Noble Gas] (n-1)d^1-10 ns^0-2

• First row (3d series): Sc (Z=21) to Zn (Z=30)
• Second row (4d series): Y (Z=39) to Cd (Z=48)
• Third row (5d series): La (Z=57), Hf (Z=72) to Hg (Z=80)

3. Occurrence and Characteristics

• Mostly found in ores like oxides, sulphides, and halides.
• Good conductors of heat and electricity.
• Exhibit variable oxidation states.
• High melting and boiling points.

4. General Trends in Properties (First Row)

(a) Metallic Character

All are metals, show malleability, ductility, conductivity, and luster.

(b) Ionization Enthalpy

Relatively high due to nuclear attraction, but lower than s- and p-block elements.

(c) Oxidation States

These elements show variable oxidation states due to participation of (n-1)d and ns electrons.

• Fe: +2, +3
• Mn: +2 to +7

(d) Ionic Radii

Decrease across the period due to increased nuclear charge → stronger pull on electrons.

(e) Colour

Many transition metal ions are coloured due to d-d electron transitions.

(f) Catalytic Properties

• Transition metals and their compounds act as good catalysts (e.g., Fe in Haber process).

(g) Magnetic Properties

Paramagnetic due to unpaired d electrons. Magnetic moment:

μ = √[n(n+2)] BM

where n = number of unpaired electrons.

(h) Interstitial Compounds

• Small atoms like H, B, C, N occupy voids in metal lattice (e.g., TiC, Fe₃H).

(i) Alloy Formation

Transition metals form strong and hard alloys (e.g., brass = Cu + Zn).

5. Important Compounds

Potassium Dichromate (K₂Cr₂O₇)

• Preparation: From chromite ore.
• Properties: Orange crystals, strong oxidising agent in acidic medium.

Potassium Permanganate (KMnO₄)

• Preparation: From pyrolusite (MnO₂).
• Properties: Deep purple, strong oxidising agent in acidic, neutral, and basic media.

---

Part B: f-Block Elements

1. Lanthanides (4f Series)

Electronic Configuration

General: [Xe] 4f^1–14 5d^0–1 6s²

Oxidation States

+3 is most common; some show +2 or +4 (e.g., Ce⁺⁴, Eu⁺²).

Chemical Reactivity

• Reactive, especially with water and acids.
• Form ionic, basic oxides.

Lanthanide Contraction

Gradual decrease in size of atoms and ions across the lanthanide series due to poor shielding by 4f electrons.

Consequences of Lanthanide Contraction

• Similarity in properties of second and third-row transition elements (Zr ~ Hf).
• Separation of lanthanides becomes difficult.

2. Actinides (5f Series)

Electronic Configuration

General: [Rn] 5f^1–14 6d^0–1 7s²

Oxidation States

More variable than lanthanides, ranging from +3 to +6 (e.g., U⁺⁶).

Comparison with Lanthanides

• Actinides are more reactive.
• Show greater oxidation state variability.
• Radioactive in nature.

---

Tips for Teaching Effectively:

• Use periodic table handouts to visualize positions of d and f block.
• Compare properties across rows to reinforce trends.
• Demonstrate oxidation reactions of KMnO₄ and K₂Cr₂O₇ with common reducing agents.
• Explain magnetic properties using diagrams of d-orbital filling.
• Use mnemonic devices to help remember lanthanide series (e.g., "La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu").

Interactive Simple Harmonic Motion (SHM)

x(t) = 50 sin(1t + 0)

Amplitude (A): 50
Angular Frequency (ω): 1
Phase (ϕ in radians): 0

Equation of Cirlce

Interactive Equation of a Circle

(x - 0)² + (y - 0)² = 50²

Center X (h): 0
Center Y (k): 0
Radius (r): 50

Best Tool to Learn English Vocabulary

Learn English Vocabulary

Word: apple

Definition: A fruit that is typically round and red, green, or yellow.

MCQ SET 01 Physics Class 11

Section – A: Multiple Choice Questions

Question 1:

Which of the following is the correct representation of a 10 cm long scale?

(A) The scale of the length is 10 cm.
(B) This is a 10 cm long scale.
(C) This is a 10 cm long scale.
(D) The scale of the length is 10 c.m.

Answer: (A) The scale of the length is 10 cm.

Explanation: Units should be symbolically represented without dots unless they appear at the end of a sentence as a full stop.

Question 2:

The displacement (in meters) of a body varies with time t (in seconds) as x = t² - 2t - 3. The displacement is zero for a positive value of t equal to:

(A) 1 s
(B) 4 s
(C) 3 s
(D) 2 s

Answer: (C) 3 s

Explanation: Given x = t² - 2t - 3. For x = 0, 0 = (t + 1)(t - 3) so t = 3, -1.

Question 3:

If A = B + C and the magnitudes of A, B, and C are 5, 4, and 3, respectively, then the angle between A and C is:

(A) sin^-1 (3/5)
(B) cos^-1 (3/5)
(C) cos^-1 (4/5)
(D) sin^-1 (4/5)

Answer: (B) cos^-1 (3/5)

Question 4:

Application of lubricants cannot reduce:

(A) Static friction
(B) Sliding friction
(C) Rolling friction
(D) Inertia

Answer: (D) Inertia

Question 5:

A force of 49 N is just able to move a block of mass 10 kg on a rough horizontal surface. The coefficient of friction is:

(A) 0.5
(B) 1.0
(C) 0
(D) 0.8

Answer: (A) 0.5

Question 6:

When a body is dropped from a tower, then there is an increase in its:

(A) Weight
(B) Acceleration
(C) Velocity
(D) Gravitational potential energy

Answer: (C) Velocity

Question 7:

A cyclist comes to a skidding stop in 20 m. During this process, the force on the cycle due to the road is 100 N and is directly opposed to the motion. Work done by the road on the cycle is:

(A) -2000 J
(B) 2000 J
(C) 1000 J
(D) 100 J

Answer: (A) -2000 J

Question 8:

On which of the following factors does the moment of inertia of an object not depend?

(A) Axis of rotation
(B) Angular velocity
(C) Distribution of mass
(D) Mass of an object

Answer: (B) Angular velocity

Question 9:

Escape velocity of an object of mass m is proportional to:

(A) m²
(B) m
(C) m^-1
(D) m⁰

Answer: (D) m⁰

Question 10:

Rigidity modulus and Young’s modulus are respectively η and Y. A copper wire of length L and area of cross-section A is pulled so that its length becomes 5L and area of cross-section becomes A/5. So:

(A) Y increases, η decreases.
(B) η increases, Y decreases.
(C) Both Y and η increase.
(D) Both Y and η remain unchanged.

Answer: (D) Both Y and η remain unchanged.

Kepler's laws of motion

Kepler's Laws of Planetary Motion

Johannes Kepler, a German mathematician and astronomer, formulated three fundamental laws to describe the motion of planets in the 17th century. These laws provided a revolutionary understanding of planetary orbits, moving away from the ancient belief in perfect circular orbits to elliptical orbits. Let’s explore each of Kepler's Laws in detail:

1. Kepler's First Law: The Law of Ellipses

The First Law states that planets move in elliptical orbits with the Sun at one focus of the ellipse. Mathematically, this can be expressed as:

r = ^{a(1 − e²)} / _{1 + e cos θ}

where r is the distance of the planet from the Sun, a is the semi-major axis of the ellipse, e is the eccentricity of the orbit, and θ is the angle from the closest approach to the Sun.

2. Kepler's Second Law: The Law of Equal Areas

The Second Law, or the Law of Equal Areas, describes how a line segment joining a planet and the Sun sweeps out equal areas in equal intervals of time. This means that when a planet is closer to the Sun, it travels faster, and when it is farther from the Sun, it travels slower. The mathematical expression for the area swept per unit time (angular momentum) is:

dA / dt = ¹/₂ r² dθ / dt = constant

where dA is the area swept out, r is the distance to the Sun, and dθ/dt is the rate of change of the angle.

3. Kepler's Third Law: The Law of Harmonies

The Third Law establishes a relationship between the distance of a planet from the Sun and its orbital period. According to this law, the square of a planet’s orbital period (T) is proportional to the cube of the semi-major axis (a) of its orbit:

T² ∝ a³

This can also be written as:

T² = k a³

where k is a constant that depends on the mass of the Sun. This law allowed astronomers to predict the motion of planets with greater accuracy.

Explore Kepler's Laws in Animation

To better visualize these laws, you can view an animation that demonstrates Kepler’s Laws in action. Visit the following link to see the planetary motions and how each law applies to them:

Click here to view animation of Kepler's Laws of Planetary Motion

Kepler’s Laws not only transformed our understanding of the Solar System but also laid the groundwork for Newton’s Law of Gravitation, further enhancing our comprehension of celestial mechanics.

By understanding these laws, we gain insight into the structure and order of our Solar System, as well as the mechanics that govern planetary bodies across the universe.

Kepler's Laws of planetary motion

Understanding Kepler's Laws of Planetary Motion

Kepler's Laws of Planetary Motion describe how planets move around the sun. These laws, formulated by the German astronomer Johannes Kepler in the early 17th century, are foundational for understanding orbits in our solar system and beyond. Below is an animation demonstrating each of Kepler's laws in action. The animation includes a planet orbiting the sun and a satellite orbiting that planet.

Kepler's Laws in Action

Kepler's Laws in Action

Kepler's First Law: Elliptical orbit with the Sun at one focus.

Kepler's Second Law: Equal areas swept in equal times.

Kepler's Third Law: Relationship between distance and orbital period.

Explanation of Kepler's Laws

Kepler's First Law: The Law of Ellipses

According to Kepler's First Law, planets orbit the Sun in an elliptical path, with the Sun located at one of the foci of the ellipse. This means that the distance between the planet and the Sun varies throughout the orbit, contrary to the earlier belief that planets move in perfect circles.

Kepler's Second Law: The Law of Equal Areas

Kepler's Second Law states that a line segment connecting a planet to the Sun sweeps out equal areas during equal intervals of time. This means that when a planet is closer to the Sun, it moves faster, and when it is farther from the Sun, it moves slower. This law helps explain why planets speed up near the Sun and slow down as they move away.

Kepler's Third Law: The Law of Harmonies

Kepler's Third Law establishes a relationship between the orbital period of a planet and its average distance from the Sun. Specifically, the square of a planet's orbital period (the time it takes to complete one orbit) is directly proportional to the cube of the semi-major axis of its orbit. This law shows that planets further from the Sun take much longer to complete an orbit than planets that are closer.

Science Class 9

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Q.1 What desirable character must be kept in mind while choosing variety of strain of crop?

High yield, resistance to diseases and pests, adaptability to climate, early maturity, and tolerance to drought, salinity, and lodging are essential. Nutritional value, market demand, post-harvest stability, and suitability for sustainable practices are also important.

Q.2 What is hybridisation?

Hybridisation is the process of crossing two genetically different plants to produce a new variety with desired traits, such as higher yield, better resistance, or improved quality.

Q.3 Explain the type of crossing?

There are two main types of crossing: Intraspecific crossing, which involves crossing two varieties of the same species, and Interspecific crossing, where two different species are crossed to create hybrids with new traits.

Q.4 What are genetically modified crops? How do these help in crop improvement?

Genetically modified (GM) crops are plants that have been altered using genetic engineering techniques to introduce desirable traits like pest resistance, herbicide tolerance, or improved nutrition. They enhance crop yield, reduce pesticide use, and increase resistance to environmental stresses.

Q.5 State some factors for which variety improvement is done?

Variety improvement is done to enhance yield, resistance to diseases and pests, adaptability to different environments, nutritional quality, and market value. It also aims to improve post-harvest storage and sustainability.

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MCQ Computer Networks HP board Computer Science

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Computer Science Quiz 01 (Computer Networks)

1. When was the first message sent over the ARPANET, one of the precursors to the internet?

a) 1969
b) 1985
c) 1995
d) 2000

Answer: a) 1969

2. Who is often referred to as the "Father of the Internet"?

a) Bill Gates
b) Tim Berners-Lee
c) Vint Cerf
d) Mark Zuckerberg

Answer: c) Vint Cerf

3. What does HTTP stand for in the context of the internet?

a) HyperText Transfer Protocol
b) High-Tech Transmission Process
c) Hostile Takeover Tactics
d) Home Testing Protocol

Answer: a) HyperText Transfer Protocol

4. Which country's academic and research institutions developed the precursor to the modern internet known as ARPANET?

a) Germany
b) United States
c) Japan
d) United Kingdom

Answer: b) United States

5. In what year did the World Wide Web become publicly available?

a) 1980
b) 1991
c) 2000
d) 2010

Answer: b) 1991

6. What was the original purpose of ARPANET, the precursor to the internet?

a) Military communication
b) Online shopping
c) Social networking
d) Scientific research

Answer: a) Military communication

7. Who coined the term "surfing the internet"?

a) Al Gore
b) Tim Berners-Lee
c) Steve Jobs
d) Jim Clark

Answer: c) Steve Jobs

8. Which protocol is commonly used for sending and receiving email over the internet?

a) SMTP
b) HTTP
c) FTP
d) TCP

Answer: a) SMTP

9. What was the first web browser developed by Tim Berners-Lee?

a) Netscape Navigator
b) Internet Explorer
c) Mozilla Firefox
d) WorldWideWeb

Answer: d) WorldWideWeb

10. The Internet was originally created to ensure the uninterrupted flow of information in the event of a nuclear attack. What was this project called?

a) Project Gutenberg
b) Project Apollo
c) Project Mercury
d) Project RAND

Answer: d) Project RAND

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Digital Literacy Advanced Class 10th

 NMPHS SAPERU

(REVISION) 

Chapter 1 

Digital Literacy (advanced) 

Q.1. What do you mean by overhead Projector? 

Ans: A projector is capable of projecting enlarged images of written or  pictorial material onto a screen or wall. An overhead projector is a very  basic but reliable tool used to display images onto a screen or wall. It  consists of a large box containing a cooling fan and an extremely bright  light, with a long arm extended above it. 

OHP 

Q. 2. What are the main parts of an overhead projector (OHP)? Ans: An overhead projector has following parts 

1. LAMP and Reflector 

2. Blower 

3. Base Mirror 

4. Projection stage 

5. Upper section.

Q. 3. How can you handle overhead projectors? 

Ans: steps to handle overhead projectors: 

1. Cover the transparency when you are done.  

2. Bring spare bulbs and a glove to change the bulb. 

3. Place you overhead projector on a table so it does not block you or  the screen. 

4. You need to consider is to keep the cleanliness of your lens Q . 4. Define Digital Screen. 

Ans: Digital Screen is a display device for presentation of images, text, or  video transmitted electronically, without producing a permanent record. It  include television sets, computer monitors etc. 

Q.5 What is LED? Explain. 

Ans: LED stands for Light emitting diodes. It is a two-lead semiconductor  light source. LED and LCD are liquid crystal displays. The basic  technology is the same in that, both have two layers of polarized glass  though which are liquid crystals both block and pass light. LED is a subset  of LCD TVs. LED work with a color wheel RGB. – Colored lights (RED,  green and blue) to produce more realistic and sharper colors. 

Q. 6. What are the advantages, disadvantages and applications of LED?  Ans: Advantages of LED: 

1. LED’s are more superior in terms of picture quality  

2. LED has a higher contrast ratio as compared to LCD monitor 3. LED’s are more superior in terms of picture quality  

4. LED has a higher contrast ratio as compared to LCD monitor 3. Led helps save on energy as compared to LCD or CRT 4. Can be mounted on wall or panel 

Disadvantages of LED: 

1. Expensive as compared to LCD 

2. Low Reliability  

3. Speed is very low 

Applications of LED: 

1. LED is used as a bulb in the homes and industries. 

2. LED’s are used in the motorcycles and cars. 

3. Used in the mobile phones. 

4. At the traffic light signals LED’s are used. 

Q.7. What is LCD? What are Applications, advantages and  disadvantages of LCD? 

Ans: LCD stands for liquid crystal display is a flat, thin display device  that has replaced the older CRT Display. LCD provides better picture  quality and support for large resolutions. LCD displays are thinner and  lighter than cathode ray tube(CRT) of similar display size. LCD  consists of liquid crystals sandwiched in between transparent glass  electrodes.

LCD 

Applications of LED: 

1. Liquid crystal technology has major applications in the field of  science and engineering as well as on electronic devices. 2. Liquid crystal thermometer 

3. Optical imaging 

4. Used in the medical applications. 

Advantages of LCD: 

1. Compact and light weight 

2. Can be mounted on wall or panel 

3. Cost effective 

4. Consume less energy and are more durable 

5. Available in various sizes. 

Disadvantages of LCD: 

1. Require additional light sources. 

2. Prices are more expensive compared to Plasma TV. 

3. Response time is longer.  

4. Backlight dims as the LCD ages.  

Q.8. What do you mean by Plasma display? Explain. 

Ans: Plasma technology is based on the fluorescent light bulb. A plasma  display is a computer video display in which each pixel on the screen is 

illuminated by a tiny bit of plasma or charged gas, somewhat like a tiny  neon light. Plasma displays are thinner than cathode ray tube (CRT)  displays and brighter than liquid crystal displays (LCD). A plasma display  panel (PDP) is a type of flat panel display that uses small cells containing  plasma: ionized gas that responds to electric fields. 

Advantages 

1. Better than CRT display. 

2. More compact than CRT. 

3. Better Contrast Ratios. 

4. Wide Viewing Angle 

5. Less visible motion blurs. 

6. It offers high resolution. 

7. It is slim and light in weight. 

8. It can display 16.7 million colors. 

9. It offers widescreen 16:9 ratio display. 

Disadvantages 

1. Flickering Effects. 

2. More Expensive. 

3. Uses more electrical power, on average, than an LCD TV. 4. Does not work as well at high altitudes above 6,500 feet (2,000  meters) due to pressure differential between the gases inside the  screen and the air pressure at altitude. It may cause a buzzing noise.  5. Prices are very high. 

6. They have shorter life span and there is no option to repair burnt out  tube or backlight. 

7. They have lower brightness levels. 

8. Susceptibility to Degradation. 

Q. 9. What do you mean by Fax Machine. Explain? 

Ans: Fax machine is a device that sends and receives printed pages or  images over telephone lines by digitizing the material with an internal  optical scanner and transmitting the information as electronic signals.

The transmissions it sends are called "faxes" and these can be sent between  two fax machines or between fax machine and computer. 

It is basically used to transmit documents between locations. The majority  of the time these are business documents. 

Advantages of Fax Machine 

1. Inexpensive- sending a message just at the cost of a telephone call. 2. They are simple to use and require very little training. 

3. As long as the fax machine is switched on, messages can be received  at any time day or night. 

Disadvantages of Fax Machine 

1. You might dial the wrong number and send your document to  someone else. 

2. If the receiving machine is busy your fax will not be delivered. 3. It can take a long time to transmit if you have many sheets of paper. 

Uses of Fax Machine 

1. Fax machines are used to transmit documents between locations. 2. Copying- A fax machine can also function as a photocopier.

Fax Machine 

Q.10. What are the steps to sending fax. 

Ans: Steps to sending fax:  

1. The original document is scanned with a Fax machine 2. Fax machines process the contents 

3. Converts it into a bitmap 

4. Transmit it through telephone lines 

Sending a fax 

1. Turn on the fax machine 

2. Insert you documents 

3. Dial the fax number 

4. Press send button 

5. Wait for the document to finish transmitting. 

Q. 11. What do you mean by Speakers? 

Ans: Speakers are an output device. They receive audio input from  the computer's sound card and produce audio output in the form of  sound waves. It is used to listen sounds from computer. Speakers  usually come in pairs, which allow them to produce stereo sound  from two separate audio channels. 

Speakers are in different shapes and sizes 

Some speakers have equalization features such as bass and treble  controls. 

Advantages of Speakers 

1. They help blind people. 

2. Sound amplification (make it louder) 

3. Very simple to operate 

Disadvantages of Speakers 

1. The output from speakers can disturb others. 

2. High quality speakers are expensive

Speaker 

Q.12. What is the difference between LCD, and CRT displays? Explain. Ans: Difference between LCD and CRT: 

LCD	CRT
LCD stands for Liquid crystal  display.	CRT stands for Cathode ray  tube
LCD’s are much slimmer than  CRT	The back size is bigger than the  size of the monitor
Sharp	Slightly less sharp images
Lower power usage	Higher power usage
LCD’s are free from the burn in  issue	Suffers from burn in problem
Perfect flat screen	In CRT only the outer glass that  is flat and not the actual screen

  

Q.13 What is the difference between LED, LCD and CRT? 

Ans: Difference between LED, LCD and CRT

LCD	LED	CRT or plasma
Brightness is very  poor in direct sunlight	Brightness is poor in  bright light	Should be used in a  dark place
Contrast ratio 1000:1 Contrast ratio		Contrast ratio

	1000000:1	20000:1
Color is good	Good	Excellent
LCD consume energy  very low	Varies with brightness  but usually lower than  LCD	Varies with brightness  but usually higher  than LCD

True/False : 

1. Printers are only black and white. False 

2. Laser printer is an electro static digital printer. True 

3. The transmissions send by the fax machine are called faxes. True  4. Speakers receive audio input from the computer sound card. True 5. Overhead projector is used in class room. True 

6. CRT is an old and almost outdated display screen. True 

7. Plasma displays consume more electrical power than LED. True 8. Laser printer is type of impact printer. False 

9. Inkjet printer is type of non-impact printer. True 

10. Character printer is a noisy printer. True 

11. LED stands for light emitting diodes. True  

12. Overhead projector is an input device. False 

13. LCD stands for Liquid crystal device. False 

14. Speaker is a kind of input device. False 

15. Plasma technology is based on the fluorescent light bulb. True 16. Dot matrix Printer is the fastest printer. False 

17. Plotter is a kind of input device. False 

18. Using fax, we can send copies of handwritten documents or  documents with signatures. True 

19. OHP stands for over head project. False 

20. CRT stands for cathode ray tyre. False 

21. Plasma displays are very light in weight. False