Define a memoryless system.
Ans. A system is memoryless if the output at any time instant depends only on the input at that particular instant, it is also called as static system.
@GateElectronics
Ans. A system is memoryless if the output at any time instant depends only on the input at that particular instant, it is also called as static system.
@GateElectronics
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How to make effective short notes for GATE?
Making effective short notes is also an art, which is really important in cracking the exam, since the syllabus is huge.
🔹 Firstly, you should study the topic very well and solve all previous year questions(each and every question) related to that topic.
🔹When you have thoroughly studied the topic and questions make a note or mark important points and concepts that are repeatedly asked in past exams.
🔹You’ll find some exceptionally good questions from gate exams that require crystal clear conceptual approach,remember to add them in short notes.
Now follow some points
✔️Take a blank drawing chart(comes around 4 or 5 rs per chart)
✔️Starting from the beginning try to cover a fair part in concise ways and add only important points and go till the end to give complete touch of the subject.
✔️Try to cover all types of question from a topic and just write the formula or approach to be used.
✔️Add a conceptually good question in concise way to revise the concept in every go ,along with the formulas and a definition for important concepts.
✔️Use a highlighter to mark utmost important formulas.
✔️Add the mistake warning if you commit some silly mistake while solving question that is important (eg in Test series or solving previous years).
✔️Write always in your words which you feel comfortable as these notes are only for you.
Stick the chart on the wall
Keep revising…..
the chart technique is very helpful in learning complex formulas very easily, as photographic memory lasts longer.
By Shivom Bhargava, Mtech (IIT Kanpur)
Making effective short notes is also an art, which is really important in cracking the exam, since the syllabus is huge.
🔹 Firstly, you should study the topic very well and solve all previous year questions(each and every question) related to that topic.
🔹When you have thoroughly studied the topic and questions make a note or mark important points and concepts that are repeatedly asked in past exams.
🔹You’ll find some exceptionally good questions from gate exams that require crystal clear conceptual approach,remember to add them in short notes.
Now follow some points
✔️Take a blank drawing chart(comes around 4 or 5 rs per chart)
✔️Starting from the beginning try to cover a fair part in concise ways and add only important points and go till the end to give complete touch of the subject.
✔️Try to cover all types of question from a topic and just write the formula or approach to be used.
✔️Add a conceptually good question in concise way to revise the concept in every go ,along with the formulas and a definition for important concepts.
✔️Use a highlighter to mark utmost important formulas.
✔️Add the mistake warning if you commit some silly mistake while solving question that is important (eg in Test series or solving previous years).
✔️Write always in your words which you feel comfortable as these notes are only for you.
Stick the chart on the wall
Keep revising…..
the chart technique is very helpful in learning complex formulas very easily, as photographic memory lasts longer.
By Shivom Bhargava, Mtech (IIT Kanpur)
👍58❤15🔥2🤩1
🧠 What is an Intrinsic Semiconductor?
An intrinsic semiconductor is a pure form of a semiconductor — nothing extra added, no chemicals mixed in. It’s like plain milk — no sugar, no flavor. The most common examples are silicon (Si) and germanium (Ge).
⸻
🔬 How Does It Work?
Every atom in an intrinsic semiconductor shares its electrons with neighboring atoms. These shared electrons form covalent bonds. At room temperature, a few of these bonds break naturally because of heat (even room temperature has some heat energy).
When a bond breaks:
• One free electron is released (it can move and carry electricity).
• One hole is left behind (an empty space where the electron was).
This electron-hole pair moves around and helps conduct electricity.
💡 Key point: In an intrinsic semiconductor, the number of electrons = number of holes.
🧪 Example to Understand Better
Imagine a dance floor (the semiconductor crystal). All dancers (electrons) are holding hands (in bonds). When the music (heat) starts playing, a few dancers let go and start dancing freely (free electrons), leaving behind empty spots (holes). These moving dancers and empty spots are what let electricity flow.
⸻
🤔 Why Do We Study This?
Even though intrinsic semiconductors don’t conduct much on their own, they are the starting point for creating better semiconductors. When we add impurities to them (called doping), we get extrinsic semiconductors — which are used in making transistors, solar cells, diodes, etc.
⸻
📝 Exam Facts You Must Remember
• Intrinsic = pure
• Electrons = holes
• Conductivity increases with temperature
• Used as base for doping
• Examples: Silicon and Germanium
An intrinsic semiconductor is a pure form of a semiconductor — nothing extra added, no chemicals mixed in. It’s like plain milk — no sugar, no flavor. The most common examples are silicon (Si) and germanium (Ge).
⸻
🔬 How Does It Work?
Every atom in an intrinsic semiconductor shares its electrons with neighboring atoms. These shared electrons form covalent bonds. At room temperature, a few of these bonds break naturally because of heat (even room temperature has some heat energy).
When a bond breaks:
• One free electron is released (it can move and carry electricity).
• One hole is left behind (an empty space where the electron was).
This electron-hole pair moves around and helps conduct electricity.
💡 Key point: In an intrinsic semiconductor, the number of electrons = number of holes.
🧪 Example to Understand Better
Imagine a dance floor (the semiconductor crystal). All dancers (electrons) are holding hands (in bonds). When the music (heat) starts playing, a few dancers let go and start dancing freely (free electrons), leaving behind empty spots (holes). These moving dancers and empty spots are what let electricity flow.
⸻
🤔 Why Do We Study This?
Even though intrinsic semiconductors don’t conduct much on their own, they are the starting point for creating better semiconductors. When we add impurities to them (called doping), we get extrinsic semiconductors — which are used in making transistors, solar cells, diodes, etc.
⸻
📝 Exam Facts You Must Remember
• Intrinsic = pure
• Electrons = holes
• Conductivity increases with temperature
• Used as base for doping
• Examples: Silicon and Germanium
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What is an Extrinsic Semiconductor?
An extrinsic semiconductor is a semiconductor that has been “spiced up” with impurities (this process is called doping).
Think of it like this:
You add special guests to a party (the impurities), and suddenly the party (electricity flow) becomes more fun and active.
⸻
3. Two Types of Extrinsic Semiconductors
1. N-type (Negative-type):
• Add impurities that give extra electrons (like adding more cars to the road).
• Example: Doping silicon with phosphorus.
• Now, electricity flows better because of these extra electrons.
👉 Think of it as a road where new cars are gifted for free.
2. P-type (Positive-type):
• Add impurities that create holes (like empty parking spots where cars can enter).
• Example: Doping silicon with boron.
• Electricity flows because cars (electrons) jump to fill these holes.
👉 Think of it as a road with extra parking spots, so cars keep moving to fill them.
⸻
4. Real-Life Example
• PN Junction Diode:
When you join P-type and N-type semiconductors, you get a diode → lets current pass in only one direction.
• This is the basis of LEDs, phone chargers, solar panels, etc.
⸻
5. Super Simple Analogy
• Intrinsic Semiconductor: Just a road. Cars move only when you push them.
• Extrinsic Semiconductor: You add either extra cars (N-type) or extra parking spots (P-type) → Now traffic moves much better and faster.
⸻
👉 Extrinsic semiconductors are the real heroes in electronics. Every chip in your phone, computer, or TV is made using them.
An extrinsic semiconductor is a semiconductor that has been “spiced up” with impurities (this process is called doping).
Think of it like this:
You add special guests to a party (the impurities), and suddenly the party (electricity flow) becomes more fun and active.
⸻
3. Two Types of Extrinsic Semiconductors
1. N-type (Negative-type):
• Add impurities that give extra electrons (like adding more cars to the road).
• Example: Doping silicon with phosphorus.
• Now, electricity flows better because of these extra electrons.
👉 Think of it as a road where new cars are gifted for free.
2. P-type (Positive-type):
• Add impurities that create holes (like empty parking spots where cars can enter).
• Example: Doping silicon with boron.
• Electricity flows because cars (electrons) jump to fill these holes.
👉 Think of it as a road with extra parking spots, so cars keep moving to fill them.
⸻
4. Real-Life Example
• PN Junction Diode:
When you join P-type and N-type semiconductors, you get a diode → lets current pass in only one direction.
• This is the basis of LEDs, phone chargers, solar panels, etc.
⸻
5. Super Simple Analogy
• Intrinsic Semiconductor: Just a road. Cars move only when you push them.
• Extrinsic Semiconductor: You add either extra cars (N-type) or extra parking spots (P-type) → Now traffic moves much better and faster.
⸻
👉 Extrinsic semiconductors are the real heroes in electronics. Every chip in your phone, computer, or TV is made using them.
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What is a PN Junction?
A PN junction diode is created when we join:
• P-type semiconductor (positive): Has extra parking spots (holes).
• N-type semiconductor (negative): Has extra cars (electrons).
👉 Imagine two roads joined together:
• One side has too many cars (N-type).
• The other side has too many parking spots (P-type).
When they meet, cars want to fill parking spots → forming a junction.
⸻
2. The Junction Behavior
At the border (junction), cars (electrons) rush to fill the nearest parking spots (holes).
• This creates a barrier/gate → like a toll booth on the road.
• Cars can’t cross freely anymore unless you pay the toll (give energy/voltage).
⸻
3. Two Conditions of a Diode
🔴 Reverse Bias (blocked state)
• If you connect the battery the “wrong” way, the barrier gets bigger.
• Cars (electrons) are pushed away from the toll booth.
• No traffic flows → diode acts like a closed road.
👉 Electricity does not flow.
⸻
🟢 Forward Bias (conducting state)
• If you connect the battery the “right” way, the barrier becomes smaller.
• Cars can easily cross the toll booth into parking spots.
• Traffic flows smoothly in one direction.
👉 Electricity flows only in one direction.
⸻
4. Real-Life Example
• Phone Charger: AC (which changes direction) is converted into DC (one-direction flow) using diodes.
• LED (Light Emitting Diode): Same PN junction, but it also emits light when current flows.
⸻
5. Analogy Recap
• PN junction diode = One-way road with a toll booth.
• Cars (electrons) can pass only one way (when the toll is paid = forward bias).
• In the opposite direction, the road is completely blocked (reverse bias).
A PN junction diode is created when we join:
• P-type semiconductor (positive): Has extra parking spots (holes).
• N-type semiconductor (negative): Has extra cars (electrons).
👉 Imagine two roads joined together:
• One side has too many cars (N-type).
• The other side has too many parking spots (P-type).
When they meet, cars want to fill parking spots → forming a junction.
⸻
2. The Junction Behavior
At the border (junction), cars (electrons) rush to fill the nearest parking spots (holes).
• This creates a barrier/gate → like a toll booth on the road.
• Cars can’t cross freely anymore unless you pay the toll (give energy/voltage).
⸻
3. Two Conditions of a Diode
🔴 Reverse Bias (blocked state)
• If you connect the battery the “wrong” way, the barrier gets bigger.
• Cars (electrons) are pushed away from the toll booth.
• No traffic flows → diode acts like a closed road.
👉 Electricity does not flow.
⸻
🟢 Forward Bias (conducting state)
• If you connect the battery the “right” way, the barrier becomes smaller.
• Cars can easily cross the toll booth into parking spots.
• Traffic flows smoothly in one direction.
👉 Electricity flows only in one direction.
⸻
4. Real-Life Example
• Phone Charger: AC (which changes direction) is converted into DC (one-direction flow) using diodes.
• LED (Light Emitting Diode): Same PN junction, but it also emits light when current flows.
⸻
5. Analogy Recap
• PN junction diode = One-way road with a toll booth.
• Cars (electrons) can pass only one way (when the toll is paid = forward bias).
• In the opposite direction, the road is completely blocked (reverse bias).
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