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Showing posts from July, 2012

### XI Chap # 01

Chapter 1 - The Scope of Physics
1. The branch of physical science, which deals with interaction of matter and energy, is called __________. (Physics, Chemistry, Biology) 2. The new era of modern physics began near the end of __________. (17th century, 18th century, 19th century) 3. Screw and lever were invented by __________. (Newton, Huygen, Archimedes) 4. Pythagoras is famous in __________. (Physics, Chemistry, None of these) 5. In the field of research the strong incentive comes from __________. (Bible, Quran, Ingeel) 6. Number of ayah which are taken from Surah Nooh for our book are __________. (11 and 12, 13 and 14, 15 and 16) 7. Number of ayah taken from Surah ‘Al Imran’ __________. (170 and171, 180 and 181, 190 and 191) 8. Al-Khawarizmi was the founder of __________. (Microbiology, Analytical Algebra, Physics) 9. Logarithm was invented by __________. (Al- Beruni, Al-Khawarizmi, Ibn-e- Sina) 10. In Muslim world the man was both a poet and a mathematician is __________.…

### XII :Chap # 11

Heat
1.      The energy that flows from a high temperature object to a low temperature object is called __________. (Heat, Sound Electricity, Solar Energy) 2.      Hotness or coldness of an object is expressed in tems of a quantity called __________. (Heat, Temperature, Kelvin, None of these) 3.      The SI unit of heat is __________. (Calorie, Joule, Electron Volt, None of these) 4.      The energy expended when a force of one Newton moves an object one metre in the direction in which the force is applied is called __________. (Calorie, Joule, kwh, Electron Volt) 5.      1J=__________. (1Nm, 1kgms2, 1kgm-2,1kgm2s-1) 6.      1J = __________. (kgms, 1 kgms2, 1kgm2s-2, 1kgm2s-1) 7.      The average kinetic energy of the molecules of the object is called its __________. (Heat, Temperature, Hotness, Coldness) 8.      __________ is a device used to measure the degree of hotness or coldness of the object. (Thermometer, Barometer, Hypsometer, None of these) 9.      Generally thermometers make use o…

### Physics CH # 18 Review Questions
Q.1 The bohr theory of hydrogen atom is based upon many assumptions. Do any of these assumption contradict classical physics? Ans: The assumption in bohr’s theory that an electron moving around the nucleus in a certain orbit does not radiate energy is contrary to the classical physics.
Q.2 Why does the hydrogen gas produced in laboratory not glow and emit radiations? Ans: A spectrum is given by the light emitted from an incandescent gas or vapors. For example electric discharge through a gas or hydrogen filled discharge tube
Q.3 Why are the energy levels of the hydrogen atom less than zero? Ans:The energy levels of hydrogen are negative. This shows that an electron must do that amount of work to escape from electron or to over come the binding energy of that orbit.
Q.4 If hydrogen gas is bombarded by electrons of energy 13.6 eV, would you expected to observe all the lines of hydrogen spectrum? Ans:the Hydrogen will get ionized because 13.6 is the energy of ground state an…

### Physics CH # 19 Review Questions Q.2 Do α, β and γ rays came from the same element .Why do we find all three in many radioactive elements? Ans: A radioactive element either emits α-particles or β-Particles ,but never both. Gamma radiations are the companion of alpha or beta. So the radioactive sample is the mixture of radioactive elements so we can have all three in many.
Q.3 It is more difficult to start a fusion reaction that fission. Why? Ans:In fission there in no extra work done to overcome the repulsive force between two protons as in the nuclear fusion so that is why it is difficult to produce he nuclear fusion
Q.4 Is it possible that fusion of two small nuclei may occur without collision at extremely high energy? Ans:No .Two nuclei must collide with sufficient kinetic energy to penetrate their mutual columb barrir and coming with in the range of nuclear forces.
Q.6 What are benefits and risks of nuclear reactors? Which reactor is relatively better from the point of safety?

Ans: Benefits Risk  Prod…

### Physics CH # 20 Review Questions
Q.20.1 Explain how would you test whether the radiation from a radioactive source are γ, β, α Particles? Ans. If the radiations are allowed to pass from a magnetic field then the radiations can be identified because of the deflection the α and β particles changes their path and γ rays pass went un deflected.
Q.20.2 A particle produces more ionization is less penetrating. Why? Ans. Due to the ionization the particle losses some part of energy. so it will have small penetrating power so we can say that the grater ionization the more will be loss of energy and less will be penetrating power..
Q.20.3 It is said that α or β Particles carries an atom with out colliding with electrons. How can each do so? Ans. As we know tat the charge on α particle is positive while β has the negative charge. Therefore the α particle ionizes the atom by attraction and  β  particle ionizes by repulsion.
Q.20.4 In how many ways γ rays produce ionization of the atoms? Ans. (i) It may lose only a p…

### Physics CH # 9 Definitions:
1. Machine:A machine is a device by means of which useful work can be performed conveniently and it can also transfer one form of energy into another form of energy.
2. Mechanical Advantage:The ratio between the resistance or weight to the power applied in a machine is called the mechanical advantage of that machine. It is denoted by M.A.
M.A. = Weight over-comed by Machine/ Force Applied on the Machine
3. Efficiency:The ratio between the useful work done and the work done on the machine is called efficiency.
M.A = (output/Input) * 100
4. Input:Input is the work done on the machine.
5. Output:Output is useful work done by the machine.
Lever:
DefinitionLever is the simplest machine in the world. It is a rigid bar, which can be rotated about a fixed point.
Principle Of Lever
In the lever the moment P acts opposite to that of work W. It means that force F tends to rotate the lever in one direction which the weight W rotates in opposite direction. If the magnitude of these moments act…