Albert Einstein theoretically proposed the existence of gravitational waves in the year 1915.

Proton and neutron are made up of quarks. Later, it was found that Higg's particles or God particles give mass to the particles like protons, neutrons etc.

Parrot fish's source of bite → mimic → Ultra durable synthetic material.
Lotus leaf surface → SEM → Self Cleaning Process
The scales on the wings of a morpho butterfly → mimic → Interaction of colours.
Peacock feathers → mimic → Glowing in different colours.

Wings of a morpho butterfly, peacock feathers, lotus leaf surface and sources of parrot fish's bite are some of the natural nano particles.

Ground wave propagation: frequency less than 2 MHz
Sky wave propagation: 3 to 30 MHz
Space wave propagation: Above 30 MHz to 400 GHz
Satellite communication: uplink communication 6 GHz band downlink communication 4 GHz band

A = 1, B = 0, C = 1
y = A + B, y = (A + B).C
y = (1 + 0).1 ⇒ y = 1

\(Y_1=\overline{A+B}, y_2=\overline{A+B}=A+B, y=\overline{A+B}\)

NAND and NOR gates are known as universal gates because any other logic gate can be made from NAND or NOR gates.

The shortest distance between the transmitter and the point of reception of the sky wave along the surface is called as the skip distance.

Black holes are end stage of stars whose mass ranges from 20 times to 1 million times the mass of the sun. Because of their dense mass, they have very strong gravitational force such that no particle or even light can escape from it. Therefore they are not visible to human eye. Every galaxy has black hole at its center. 

(i) The scales on the wings of a morpho butterfly.
(ii) Peacock feathers.

(i) If the particle of a solid is of size less than 100 nm, it is said to be a nano solid, if the particle size exceeds 100 nm, it is a bulk solid.
(ii) Both have same chemical properties. But their mechanical, electrical, optical, magnetic properties differ.

RADAR stands for RAdio Detection And Ranging.

The total distance d between the transmitting and receiving antennas will be the sum of the individual distances of coverage.
d = d₁ + d₂
\(=\sqrt { 2R{ h }_{ 1 } } +\sqrt { 2{ Rh }_{ 2 } } \)
\(=\sqrt { 2R } \left( \sqrt { { h }_{ 1 } } +\sqrt { { h }_{ 2 } } \right) \)
\(=\sqrt { 2\times 6.4\times { 10 }^{ 6 } } \times (\sqrt { 40 } +\sqrt { 30 } )\)
\(=16\times { 10 }^{ 2 }\sqrt { 5 } \times (6.32+5.48)\)
= 42217 m = 42.217 km

(i) The satellite communication is a mode of transmission of signal between transmitter and receiver via satellite.
(ii) The message signal from the Earth station is transmitted to the satellite on board via an uplink (frequency band 6 GHz), amplified by a transponder and then retransmitted to another earth station via a downlink (frequency band 4 GHz).
Applications:
Satellites are classified into different types based on their applications.
(i) Weather Satellites:
They are used to monitor the weather and climate of Earth. By measuring cloud mass, these satellites enable us to predict rain and dangerous storms like hurricanes, cyclones etc.
(ii) Communication satellites:
They are used to transmit television, radio, internet signals etc. Multiple satellites are used for long distance communication
(iii) Navigation satellites:
These are employed to determine the geographic location of ships, aircraft or any other object.

(i) Radar basically stands for Radio Detection and Ranging System.
(ii) It is one of the important applications of communication systems' and is mainly used to sense, detect, and locate distant objects like aircraft, ships, spacecraft, etc.
(iii) The angle, range, or velocity of the objects that are invisible to the human eye can be determined.
(iii) Radar uses electromagnetic waves for communication. The electromagnetic signal is initially radiated into space by an antenna in all directions.
(iv) When this signal strikes the targeted object, it gets reflected or reradiated in many directions.
(v) This reflected (echo) signal is received by the radar antenna which in turn is delivered to the receiver.
(vi) Then, it is processed and amplified to determine the geographical statistics of the object. The range is determined by calculating the time taken by the signal to travel from RADAR to the target and back.
Applications :
Radars find extensive applications in almost all fields.
(i) In military, it is used for locating and detecting the targets.
(ii) It is used in navigation systems such as ship borne surface search, air search and weapons guidance systems.
(iii) To measure precipitation .rate and wind speed in meteorological observations, Radars are used.
(iv) It is employed to locate and rescue people in emergency situations.

Advantages of robotics:
(i) The robots are much cheaper than humans.
(ii) Robots never get tired like humans. It can work for 24 x 7. Hence absenteeism in work place can be reduced.
(iii) Robots are more precise and error free in performing the task.
(iv) Stronger and faster than humans.
(v) Robots can work in extreme environmental conditions: extreme hot or cold, space or underwater. In dangerous situations like bomb detection and bomb deactivation.
(vi) In warfare, robots can save human lives.
(vii) Robots are significantly used in handling materials in chemical industries especially in nuclear plants which can lead to health hazards in humans.
Disadvantages of Robotics:
(i) Robots have no sense of emotions or conscience.
(ii) They lack empathy and hence create an emotionless workplace.
(iii) If ultimately robots would do all the work, and the humans will just sit and monitor them, health hazards will increase rapidly.
(iv) Unemployment problem will increase.
(v) Robots can perform defined tasks and cannot handle unexpected situations.
(vi) The robots are well programmed to do a job and if a small thing goes wrong it ends up in a big loss to the company.
(vii) If a robot malfunctions, it takes time to identify the problem, rectify it, and even reprogram if necessary. This process requires signi cant time.
(viii) Humans cannot be replaced by robots in decision making.
(ix) Till the robot reaches the level of human intelligence, the humans in work place will exit.

First Theorem :
The complement of the sum of two logical inputs is equal to the product of its complements.
\(\overline { A+B } \) = \(\bar { A } .\bar { B } \)
Proof:
(i) The Boolean equation for NOR gate is Y = \(\overline { A+B } \)
(ii) The Boolean equation for a bubbled AND gate is Y =\(\bar { A } .\bar { B } \)
(iii) Both cases generate same outputs for same inputs. It can be verified using the following truth

(i) From the above truth table, we can conclude \(\overline { A+B } \) = \(\bar { A } .\bar { B } \)
(ii) Thus De Morgan's first theorem is proved.
(iii) Hence, a NOR gate is equal to a bubbled AND gate

Second theorem :
The complement of the product of two is equal to the sum of its complements
\(\overline { A.B } \) = \(\bar { A } +\bar { B } \)
Proof:
(i) The Boolean equation for NAND gate is Y = \(\overline { A.B } \)
(ii) The Boolean equation for bubbled OR gate is Y = \(\bar { A } +\bar { B } \)
(iii) A and B are the inputs and Y is the output. The above two equations produces the same output for the same inputs. It can be verified by using the truth table.

(i) From the above truth table, we can conclude \(\overline { A.B } \) = \(\bar { A } +\bar { B } \)
(ii) Thus, De Morgan's second therom is proved.
(iii) Hence, a NAND gate is equal to a bubbled OR gate.

LHS:
AC (1 + B) = AC .1 [1 + B = 1]
AC.1 = AC
Therefore AC + ABC = AC

(i) Nano-robots in blood stream to perform small surgical procedures, to fight against bacteria, repairing individual cell in the body.
(ii) It can travel into the body and once after the job is performed it can find its way out. Chinese scientists have created the world's first autonomous DNA robots to combat cancer tumours.

i) Weather Satellites : They are used to monitor the weather and climate of Earth. By measuring cloud mass, these satellites enable us to predict rain and dangerous storms like hurricanes, cyclones, etc.
ii) Navigation satellites : These are employed to determine the geographic location of ships, aircraft or any other object.
iii) Communication satellites: Thev are used to transmit television, radio, internet signals etc. Multiple satellites are used for long distance communication.

(i) Noise level is high
(ii) Low efficiency
(iii) Small operating range

Advantages of AM :
(i) Easy transmission and reception
(ii) Lesser bandwidth requirements
(iii) Low cost
Limitations of AM :
i) Noise level is high
i) Low efficiency
ii) Small operating range

The innovation in medical diagnosis has taken leaps and bounds due to integration of technology and basic physics. A few of such advancements are discussed below:
Virtual reality :
Medical virtual reality is effectively used to stop the brain from processing pain and cure soreness in the hospitalized patients. Virtual reality has enhanced surgeries by the use of 3D models by surgeons to plan operations. It helps in the treatment of Autism, Memory loss, and Mental illness.
Precision medicine (or) customised health care :
In this approach, individual variability in genes, environment and life style for each person are aken into account for disease treatment and prevention. Hence, it is possible to customise health care. Medical decisions, treatments, practices or products and others are tailored to the individual patient.
Health wearables :
It is a device used for tracking a wearer's vital signs or health and fitness related data, location, ete. Medical wearables with artificial intelligence and big data provide an added value to healthcare with a focus on diagnosis, treatment, patient monitoring and prevention.
Artificial organs :
An artificial organ is an engineered device or tissue that is implanted or integrated into a human. It is possible to interface it with living tissue or to replace a natural organ. It duplicates or augments a specific function or functions of human organs so that the patient may return to a normal life as soon as possible.
3D Printing :
Advanced 3D printer systems and materials assist physicians in a range of operations in the medical field from audiology, dentistry orthopedics and other applications
Wireless brain sensors :
Wireless brain sensors monitor intracranial pressure and temperature and then are absorbed by the body. Hence there is no need for surgery to remove these devices.
Robotic surgery :
Robotic surgery is robotically assisted surgery helps to overcome the limitations of pre-existing minimally-invasive surgical procedures and to enhance the capabilities of surgeons performing open surgery.
Smart inhalers :
Inhalers are the main treatment option for asthma. Smart inhalers use bluetooth technology to detect inhaler use, remind patients when to take their medication and gather data to help guide care.