INTRODUCTION TO PHYSICS Chapter # 01 Physics 10th - Question Answers

 Physics 10th - Question Answers

INTRODUCTION TO PHYSICS
Chapter # 01

Q.1: What is Physics? Write the name of branches of Physics and explain them?

Ans: PHYSICS:
Physics is defined as a science which deals with the interaction of matter and energy.
OR
It is the branch of science which deals with physical properties, behavior of matter and bodies. Nowadays, Physics deals with the production of energy and their mutual relationship.

Main Branches of Physics:
Main branches of Physics are given below:

• Mechanics:
  It deals with the motion of objects with or without reference of force.

• Electricity:
  It is concerned with the phenomena and effects related to electric charges.

• Electromagnetism:
  It deals with observations, principles, laws, and methods that relate electricity and magnetism.

• Atomic Physics:
  It is concerned with the structures and properties of atoms.

• Solid State Physics:
  It is concerned with the structure and properties of solid materials.

• Nuclear Physics:
  Nuclear physics deals with the structures, properties, and reactions of the nuclei of atoms.

• Astrophysics:
  It is concerned with the study of astronomical bodies.

OR
"A branch of physics in which we study the behavior of heavenly bodies like the moon, stars, the sun, and other planets".

• Bio-Physics:
  It is concerned with the study of biological systems in the light of theories of physics.

• Plasma Physics:
  It is concerned with matter in its plasma phase. Plasma is a state of matter which consists of highly ionized atoms, bare nuclei (nuclei without electrons), and electrons.

Q.2: Write down the important role of physics in our daily life?

Ans: IMPORTANCE OF PHYSICS IN OUR DAILY LIFE:
The importance of Physics in our daily life is given below:

• Automobile technology is based on the principles of thermodynamics.
• Nuclear energy is used on a large scale to produce electric power.
• Radar technology is based on the rules of Physics.
• Lasers are widely used in medical science.
• All the electrical devices which are used as home appliances are based on physics rules and laws.

Q.3: What is a scientific method? Write down the names of its steps?

Ans: SCIENTIFIC METHOD:
It is a specific method used to search truth and reality.
OR
"The method which helps to collect facts on the basis of observations and experiments is called scientific method".

Steps of Scientific Method:
The scientific method includes the following five steps:

• Observation
• Hypothesis
• Theory
• Experiment
• Laws

Q.4: Define the steps of a scientific method?

Ans: STEPS OF A SCIENTIFIC METHOD:

• Observation:
  The process of observing natural phenomena with the help of five senses and scientific equipment is called observation. Observations are taken very carefully. All possible information is gathered about a physical phenomenon under investigation.

• Hypothesis:
  The explanation of observations and facts is called a hypothesis. A hypothesis is a notion or guess of a scientist in which he tries to explain the phenomenon.

• Theory:
  If a hypothesis is accepted, it is called a theory. Scientists design a theory on the basis of a hypothesis and provide an elaborated explanation about the phenomenon.

• Experiment:
  Scientists conduct experiments to test a theory. If a theory is proved by experiments, it is regarded as correct and accepted. If the theory is not proved by experiments, it is discarded.

• Laws:
  When a theory has been thoroughly checked under different situations and gives the same results, it becomes a law. The law explains the observations and the experiments about a physical phenomenon.

Q.5: What are the different theories of light?

Ans: THERE ARE FOLLOWING IMPORTANT THEORIES OF LIGHT AS:

• Newton’s Particle Theory or Corpuscular Theory:
  Newton made a hypothesis about the nature of light. According to Newton’s theory, light consisted of very minute but high-velocity particles, which were supposed to originate from a source of light (like the sun). These particles are called corpuscles. According to this theory, the particles of light travel faster in a denser medium than in a rarer medium.

• Huygen’s Wave Theory of Light:
  According to this theory, the particles travel through a medium called ether. The light particles travel faster in a rarer medium than in the denser medium.

• Quantum Theory of Light:
  According to this theory, light has a dual nature; sometimes it behaves like a wave and sometimes like a particle. It consists of packets of energy, which are called photons.

Q.6: Define Error? What are different types of error?

Ans: ERROR:
An error is defined as, "The difference between the measured and the actual values".

TYPES OF ERROR:
There are following types of errors as:

• Personal Error:
  Personal error can arise due to making a mistake in reading a scale. In order to record a reading from a scale, you have to line up the object you are measuring with the scale and hold your eyes in one particular position for making a correct observation.

• Systematic Error:
  This error is due to a fault in the measuring instrument and is usually called zero error, which may be positive or negative.

• Random Error:
  This error is called accidental error. It arises due to the experimental conditions, e.g., changes in temperature, humidity, voltage, etc. These are beyond the control of the person making the measurement.

Q.7: How can we find the percentage error in?

• Meter Rod
• Temperature
• Sphere
• Box
• Density

Ans: PERCENTAGE ERROR IN METER ROD:
During the measurement of a quantity, the maximum possible error of an instrument is defined as half the distance between two consecutive divisions.Examples:

Suppose a measurement rod is marked in millimeters. The likely error in the measurement on this scale would be 0.5 mm at one end. If a rod to be measured is placed along the scale, the likely error in the measurement will be 0.5 mm + 0.5 mm = 1 mm or 0.5 cm because at both ends the likely error is 0.5 mm. This error may be positive or negative because in the measurement both possibilities are there. If the rod is measured 16.2 cm in length, its numerical value should be written as (16.2 ± 0.5) cm. It means that the likely error in measurement is 0.1 cm. This error is usually expressed in percent, hence the relative possible error in the above example is:

$$\frac{0.1}{16.2}=0.006$$

Percentage error:

$$\frac{0.1}{16.2}\times 100=0.6\mathrm{\%}$$

PERCENTAGE ERROR IN TEMPERATURE:
Consider another example of measurement in which a thermometer is used. It is calibrated in 0.2°C division. In an experiment, initial and final temperatures are recorded as 20.2°C and 25.4°C. At each reading, the likely error is 0.1°C. Therefore, the error in the rise in temperature (25.4°C - 20.2°C = 5.2°C) would be (0.1°C + 0.1°C = 0.2°C). The percentage error will be:

$$\frac{0.2}{5.2}\times 100=3.8\mathrm{\%}$$

PERCENTAGE ERROR IN THE VOLUME OF A SPHERE:
Usually, in an experiment, we use a formula to find the final result. If a formula contains one or more quantities raised to some power, say the volume of a sphere is given by the formula:

$$V=\frac{4}{3}\pi r^3$$

where "r" stands for the radius of the sphere. Then, the error in the result increases due to the quantity multiplied by the power to which the quantity is raised in the original formula. In the above example:

$$V=\frac{4}{3}\pi {\left(\frac{d}{2}\right)}^3$$$$V=\frac{4}{3}\pi \times \frac{d^3}{8}$$$$V=\frac{\pi d^3}{6}$$

Where "d" stands for the diameter of the sphere. Percentage error in $V=3\times$ % error in $d$, since the diameter is raised to the power of three.

PERCENTAGE ERROR IN THE VOLUME OF A BOX:
If two or more quantities are measured in an experiment, then the error in the final result will be the sum of the error of individual quantities. For example, the volume of a box is given as:

$$V=\text{length}\times \text{breadth}\times \text{height}$$$$V=l\times b\times h$$

Then,
Percentage error in volume = % error in length + % error in breadth + % error in height.

$$V=\mathrm{\%}\text{ of }l+\mathrm{\%}\text{ of }b+\mathrm{\%}\text{ of }h$$

PERCENTAGE ERROR IN DENSITY:
If a quotient involved in a formula, say density of a material is given as:

$$\rho =\frac{\text{mass}}{\text{volume}}$$

Then percentage error in the result would again be the sum of percentage error in individual quantity. Thus, % error in density = % of $m$ + % of $V$.

Q.8: What is the Contribution of Abu Ali Hassan Ibn-Al-Haitham in the field of Physics?

Ans: ABU ALI HASSAN IBN-AL-HAITHAM CONTRIBUTIONS:

• He was a great scholar of physics, mathematics, engineering, astronomy, and medicine.
• He wrote many books on various subjects.
• He wrote a book Kitab-ul-Manazir on optics.
• He invented the pinhole camera.
• He discovered the nature of light and told that it is a kind of energy.
• He gave a formal definition of the ray of light.
• He described luminous and non-luminous objects.
• He described the working and the internal structure of the eye.

Q.9: What is the Contribution of Yaqub Ibne Ishaq-Alkindi in the field of Physics?

Ans: CONTRIBUTION OF YAQUB LBNE ISHAQ-ALKINDI:

• He produced many research monographs on meteorology, specific gravity, and on tides.
• His most important work was on sound and optics.
• He discovered a method to express musical notes in terms of frequencies.
• He also discussed the nature of sound.
• He worked on geometrical optics. One of his works on optics was translated into Latin.
• He did considerable work on medicine too.

Q.10: What is the contribution of Abu Rehan Muhammad Bin Ahmed Al-Beruni in the field of Physics?

Ans: CONTRIBUTION OF ABU REHAN MUHAMMAD BIN AHMED AL-BERUNI:

• He proved practically that the earth was round.
• He measured the circumference of the earth.
• He discussed the movement of the sun and the moon.
• He determined the longitude and latitude of a place.
• He found the density of various metals.
• He disclosed that the earth is not stationary but is floating in space.

Q.11: Write down the Contribution of Dr. Abdul Salam in the field of Physics?

Ans: CONTRIBUTION OF DR. ABDUL SALAM:

• He was awarded the Nobel Prize in Physics for his work on Grand Unification Theory (GUT).
• He established an international center for theoretical physics at Trieste, Italy, where scientists from developing countries are provided opportunities to augment their research work.
• He was an asset of Pakistan and will remain in the hearts of the learning circle.

Q.12: Write down the contribution of Dr. Abdul Qadeer Khan in the field of Physics?

Ans: CONTRIBUTION OF DR. ABDUL QADEER KHAN:

• He worked as an expert at Uren Co enrichment plant in Holland as a joint venture of the Government of Holland.
• When Dr. Abdul Qadeer Khan imbued with the supreme spirit of patriotism, he returned to Pakistan to serve his motherland.
• To honor him, the former engineering research laboratories have now been named as A.Q. Khan Research Laboratories.
• He has been awarded Hilal-e-Imtiaz by the Government of Pakistan.
• He contributed to making Pakistan a nuclear state.

Q.13: What do you mean by the teaching of Islam and science in view of QURAN and HADITHS?

Ans: IMPORTANCE OF READING IN ISLAM:
In an authentic Hadith, Saheeh Bukhari Sharif, the mode of the first revelation is narrated when the Holy Prophet (P.B.U.H) was in the cave of Hira.

"Read: in the name of the Lord who createth”.
"Createth man from a clot."
"Read: and it is thy Lord the most Bountiful”
"Who teacheth by pen, Teacheth man that which he knew not ; 

(Surah: Al - Alaq, Ayat 1-5)

It is obvious from the first revelation that reading in Islam is the most important feature of life.

Importance Of Knowledge Of Things:
In the Holy Quran, the knowledge of names of things is related to the very first man, Adam (may Allah place his soul in peace and tranquility). The superiority of Adam to angels is due to the knowledge of things:

"And he taught Adam all the names then showed them to the angels saying: inform me of the names of these if ye are truthful”.

"They said: Be glorified! We have no knowledge saving that which Thou hast taught us Lo! Thou, only Thou, art the knower, the wise”.
"He said: O Adam! Inform them of their names and when he had informed them of their names. He said: Did I not tell you that I known the secret of the heavens and the earth? And I know that which ye disclose and which ye hide”.

Hazrat Adam And Knowledge:
These verses tell us that the first man, Adam, created on the surface of the earth had knowledge of things and was not an ignorant person. It means that our very first ancestors were blessed with knowledge of things by Allah himself. Adam (may Allah place his soul in peace and tranquility) was not only the first man on the earth but also the first Prophet of Allah. Therefore, teachings of Islam from its very beginning is to acquire knowledge of things.

Hadith In Favor Of Learning And Gaining Knowledge:

• One hadith narrates:

  "Quest knowledge from cradle to grave”.

• Our Holy Prophet (P.B.U.H) said:

  "Gain knowledge if you had to travel even to China”.

  In the days of the Prophet, China was supposed a far remote land from Arabia as well as a learning seat of knowledge.

• In another hadith the Holy Prophet (P.B.U.H) said:

  "To gain knowledge is an obligation to every Muslim man and woman”.

• These and many other hadiths indicate the importance of learning and knowledge in Islam. In the light of teachings of Islam, we cannot ignore learning and gaining knowledge from all quarters of life. Of course, knowledge is the legacy of a believer.

 

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