Vectors

Q1:    What is resolution of vector?

Ans:  To resolve a vector into its components is called resolution of vectors. A vector can be resolved in to two components.

Q2:    What is head to tail rule?

Ans:  Two or more vectors can be added by using head to tail rule. According to this rule the head of first vector is joined with the tail of second vector and heat of second vector joins with the tail of third and so on. The resultant vector is directed from the tail of first vector to the head of last vector as shown in fig.

Q3:     Define negative vector?

Ans:   The negative vector (-A) of a vector A is such that it has the same magnitude as that of A but opposite direction.

Q4:     What are rectangular components of a vector?

Ans:    The components of a vector which are perpendicular to each other. The magnitude of the components are 

Fx = Fcos (theeta)               Fy = Fsin (theeta)

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Atomic And Nuclear Physics

Q:   What is half life time?
Ans:  The half life of an element is that time during which the number of atoms of that element are reduced to one half. i.e half life of uranium is 4.5 x 10⁹ years.


Q:   Define fission reaction.
Ans:  Breaking of a nucleus into two parts with the release of large amount of energy is called fission reaction. i.e 

Q:   What is Atomic Mass Number?
The sum of neutrons and protons present in a nucleus is called its Atomic Mass number. It is denoted by the letter A. i.e where 16 14 and 12 are atomic mass numbers of oxygen, nitrogen and carbon respectively.

Q:   What is natural radioactivity?
Ans:  The elements whose atomic number is greater than 82 naturally break and emit alpha, beta and gamma particles. The natural process of breaking of the elements is called natural radioactivity. i.e Uranium

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Information Technology

Q:   What do you mean by word processing?
Ans:  To type some thing, by computer’s key board, to correct to arrange, to amend documents, to add and delete the written portion when required is called word processing.


Q:   Name the input and output devices of the computer.
Ans:  The input devices of a computer are keyboard, mouse. The output devices are the monitor, floppy disc, CD and the attached printer.


Q:   Define information technology?
Ans:  The scientific method of storing, arranging information for proper use and to communicate them to others is called the information technology

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Spherical Mirrors and Lenses

Q:  What do you mean by refractive index of mirror?
Ans:  When light passes from one medium to another medium then the constant   sin I / sin r  is called the refractive index of the second medium with respect to the first medium.


Q:   What do you mean by total internal reflection?
Ans:   When light passes from denser medium to the rarer medium by increasing angle of incidence (i),the angle of refraction  also increases in such a way that ( r)  is always greater than 1 till for a particular value of angle of incidence the corresponding angle of refraction becomes 900 and the refracted ray grazes along the surface. If angle of incident increases more then refracted ray comes back to the denser medium. This is called total internal reflection.



Q:   What do you mean by critical angle?
Ans:   The angle of incidence in the denser medium for which corresponding angle of refraction is 900 in the rarer medium is called the critical angle. This angle of incidence is denoted by C.


Q:   Write two conditions of total internal reflection.
Ans:   
1. The ray of light should travel from a denser medium to a rare medium.
2. The angle of incidence should be greater than the critical angle.


Q:   State laws of reflection.
Ans:   There are two laws of refraction.
1. The angle of incidence is equal to the angle of reflection.
2. The incident ray, the reflected ray and normal at the point of incidence, all lie in the same
  plane.


Q:   What is difference between the primary and secondary Rainbow.
Ans:   The main difference is that in primary rainbow total internal refection occurs only one time but for the secondary rainbow it occurs two times and its colours are faint.

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Wave Motion

Q:   Define simple harmonic motion.
Ans:   The motion in which acceleration of the body is directly proportional to displacement and always directed towards the mean position is called simple harmonic motion.



Q:  How will you define wave motion?
Ans:  The motion which is due to the generated disturbance which causes the constituent particles to repeat its to and fro motion about its mean position in equal interval of time, and this disturbance is passed over from one end to the medium to the other.


Q:  What are transverse waves?
Ans:  Transverse waves are such waves in which the particles of the medium vibrate perpendicular to the direction o propagation of the wave.


Q:  What are compressional waves?
Ans:  The wave in which the direction of the vibratory motion of the particles of medium is parallel to the direction of propagation of wave are called compressional or longitudinal waves.


Q:  Write four properties of waves?
Ans:  The four properties of waves are:
I. Reflection   ii. Refraction   iii. Diffraction iv. Interference


Q:  What is meant by crest and trough?
Ans:  
Crest: Those parts of the transverse waves where the particles of medium are above the normal position are called trough.
Trough: Those parts of the transverse waves were the particles of the medium are below their normal position are called trough.


Q:  What is the necessary factor for Diffraction?
Ans:  Diffraction of waves can only be observed clearly if the size of the slit or obstacle in nearly equal to the wavelength of the wave.



Q:   What is difference between the amplitude and displacement of a vibrating body?
Ans:   Amplitude in the maximum distance of a vibrating body from the mean position, while the distance of vibrating body form mean position at any time is called as displacement.



Q:    What do you mean by time period?
Ans:   The time required to complete one vibration or cycle is called as time period. It is denoted by “T” . Its unit is second (S).


Q:    Write down any two characteristics of S.H.M.
Ans:   
(i) A body executing simple harmonic motion, always vibrates about its mean position.
(ii) Its acceleration is always directed towards its mean position.
(iii) Velocity is maximum at the mean position and zero at the extreme position.


Q:    What do you mean by compressional wave?
Ans:   A wave of continuous compression and rarefaction moving away from the vibrating body is called compressional wave. A wave of continuous compression and rarefaction moving away from the vibrating body is called compressional wave. A wave of continuous compression and rarefaction moving away from the vibrating body is called

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Heat

Q:  Define thermometry?
Ans:  The art of measuring temperature is known as thermometry.


Q:  Define Temperature?
Ans:  Temperature is the measure of hotness and coldness of a body.


Q:  Write the formula for conversion of Celsius to Fahrenheit scale?
Ans: 

TF = (9/5) TC + 32

Q:  Write the formula for conversion of  Fahrenheit scale to Celsius?
Ans: 

TF = (5/9) (TF - 32)

 Q:  What is the relation between Kelvin and Celsius scales?
Ans: 

TK = TC + 273

 Q:  Define thermometer?
Ans:  The instrument which is used to measure temperature is called thermometer.


Q:   Why desert nights are colder whereas days are very hot ?
Ans: Desert nights are colder whereas days are very hot because specific heat of sand is very low. It gets hot and cold fast. 


Q:   Convert 30^oC into Fahrenheit.
Ans:   T_F =(9/5) x TC + 32^o

            =(9/5) x 30 + 32

            =54 + 32 = 86^oF

Q:     What is the latent heat of fusion of ice?
Ans:   The latent heat of fusion of ice is 336,000 joules per kilogram.

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Electromagnetism

Q:  Define right hand rule?
Ans:  According to right hand rule " if we grasp the current carrying conductor in our right hand with the thumb being stretched in the direction of current, the fingers would curl in the direction of lines of force."


Q:  Define flux?
Ans: The number of magnetic lines of force passing through any surface is known as magnetic flux through that surface.


Q:  Define left hand rule?
Ans: According to this rule, stretch the thumb, forefinger and the middle finger of the left hand mutually at tight angles to each other. If the forefinger points in the direction of the magnetic field, the diddle finger in the direction of the current, then the thumb would indicate the direction of the force acting on the conductor.


Q:  Define  Faraday's law ?
Ans: Faraday's law states that "The value of the induced emf is directly proportional to the rate of change of flux."


Q:  Define working principle of D.C motor ?
Ans:  When a current carrying coil is placed in a magnetic field a couple would act on the coil due to which it rotate in magnetic field. This is the principle on which an D.C motor works.


Q:  Define working principle of A.C generator ?
Ans:  When a coil rotates in a magnetic field, the flux passing through it continuously changes. This change of flux induces an emf in the coil. This is the principle on which an A.C generator works.

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Current Electricity

Q:  Define electric current?
Ans:  The rate of flow of electric charge through any cross sectional area is called electric current.

سوال :الیکٹرک کرنٹ کی تعریف کریں ؟ 

   جواب :کسی رقبہ سے الیکٹرک چارج  کے بہنے کی شرح کو الیکٹرک کرنٹ کہتے ہیں 

I = Q/t
Unit = Ampere (A)

Q:  Define conventional current?
Ans:  The current which is due to the flow of positive charge.

سوال :کنونشنل کرنٹ کی تعریف کریں ؟

.جواب :ایسا کرنٹ جو مثبت چاجز کی وجہ سے بہتا ہے

Q:  Define electromotive force (emf)?
Ans:  The amount of energy supplied by the battery in pushing one coulomb of charge (electrons) from its positive terminal to its negative terminal through the battery is known as the electromotive force.

سوال : ای . ایم .ایف  کی تعریف کریں ؟

جواب : ای . ایم .ایف انرجی کی اس مقدار کے برابر ہوتی ہے جو کہ بیٹری ١کولمب چارج کو اپنے پوزیٹیوٹرمینل سے نیگیٹو ٹرمینل کو منتقل کرنے کے لیے مہیا کرتی ہے

Unit = Volt (V)

Q:  Define potential difference?
Ans:  It determines the energy between two points of circuit which is required in moving a charge from one part to another.

Unit = Volt (V)

Q:  Define Ohm's Law?
Ans:  The value of current I passing through a conductor is directly proportional to the potential difference V applied across its ends, provided the temperature and the physical state of the conductor does not change.

V = IR

Q:  Define limitations of Ohm's law?
Ans:  Ohm's law is applicable only in case of metallic conductors when their temperature and physical state do not change.


Q:  Define resistance?
Ans:  The property of a substance which opposes the flow of current through it is called its resistance. It is represented by letter R. Its unit is Ohm Ω.

Q:  Define ohm?
Ans:  The unit used to measure the resistance is called ohm.
"If a current of one ampere passes through it when a potential difference of one volt is applied across its ends." It is represented by the Greek letter Ω.


Q:  What are the factors upon which the resistance of conductor depend?
Ans:  The resistance R of any wire is inversely proportional to its area A and is directly proportional to its length L.

R  ∞ A
R  ∞ 1/L

Resistance also depend upon temperature. It increases with the increase in temperature.


Q:  Define galvanometer?
Ans:  An instrument which indicates the presence of current in the circuit and it also indicates the potential difference between two points. It can measure small amount of current.


Q:  Define ammeter?
Ans:  An instrument which is used to measure the value of current flowing through the circuit is called ammeter. It is attached in series in the circuit.


Q:  Define voltmeter?
Ans:  An instrument which is used to measure the value of potential difference between two points in the circuit is called voltmeter. It is attached in parallel in the circuit.


Q:  Define shunt resistance?
Ans:  A resistance of low value, which is attached in parallel to the galvanometer to convert it in to ammeter. It is represented by Rs.


Q:  Define  Joule's law ?
Ans: Joule's law states that "the amount of heat energy generated in a resistance due to the flow of electric current is equal to the product of the square of current I, the resistance R and the time duration t".

W = I² R t

Q:  Define  electric power ?
Ans: The amount of energy supplied by current in unit time is known as electric power.

P = W/t

The unit of electric power is watt.

Q:  Define  kilowatt hour?
Ans: It is the amount of energy obtained by a power of one kilowatt in one hour.

amount of energy in kilowatt-hour = (watt x time in hour)/1000

Q:  Differentiate between A.C and D.C ?
Ans: A current which always flows only in one direction is called direct current or d.c.
A current which change its direction again and again is called alternating current or a.c.

Q:  What is neutral wire?
Ans:  The wire which is at zero potential is called neutral wire.


Q:  What is fuse wire or fuse?
Ans: A small wire connected in series with the live wire. It is known as fuse wire or fuse. It is used in the circuits for safety purpose.

Q:  What is circuit breaker?
Ans:  It is a safety device used in place of fuse. Due to any fault when the current exceeds the safety limit, then the button of the circuit breaker moves upward. Due to which the circuit breaks and the flow of the current stops in it.

Q:  What is earth wire?
Ans:  An additional wire is used along with the live and neutral wires. This wire is known as earth wire because its one end is connected directly to earth by means of a water pipe leading to ground  or by means of an earth terminal.

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Electrostatics

Q:  Define Coulomb's Law?
Ans:  The force of attraction or repulsion between two charged bodies is directly proportional to the product of the quantity of charges (q1.q2) on them and inversely proportional to the square of the distance (square of r) between them.

F = (1/4πε ̥ ) q₁q₂/r²

 Q:  Define electric intensity?
Ans:  The strength of the field at any point is known as electric intensity.

E (intensity) = F/q
E = (1/4πε ̥ ) Q/r²

 Q:  Define electric field?
Ans:  The electric field of a charge is a region of space surrounding it, In which a charge can feel its electrostatic effect in the form of a force.


Q:  Define electric lines of force?
Ans:  The direction of electric intensity in an electric field can also be indicated by drawing lines. These lines are known as electric lines of force.


Q:  Define electron volt?
Ans:  It is equal to the amount of energy supplied by an electron as it moves between two points having a potential difference of one volt.

Charge on an electron = q = 1.6 x 10⁻¹⁹ C
V₁-V₂ = 1V
1eV = 1.6 x 10⁻¹⁹ C x 1V
1eV = 1.6 x 10⁻¹⁹ J

Q:  Define Farad?
Ans:  It is the capacity of a conductor the potential of which rises by one volt when one coulomb charge is given to it. This is the unit of capacitance.

 Q:  Define capacitance?
Ans:  The capacity of a conductor is equal to the amount of charge which raises the potential of the conductor by one volt. The unit of capacitance is farad.

Q = CV (here C is capacitance)

Q:  Define capacitor?
Ans:  A device used for storing charge.


Q:  Define fixed capacitor?
Ans:  If plates of capacitor are immovable or fixed then such capacitor is called fixed capacitor. e.g paper capacitor, mica capacitor.


Q:  Define variable capacitor?
Ans:  The capacitor in which plates of capacitor are movable is called variable capacitor. e.g capacitor used in tuning of a radio set.

You might also like:
Sound
Current Electricity
Circular Motion And Gravitation

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Sound

Q: What is the relation between loudness and amplitude of vibrating body?
Ans: 

Loudness ∞ Amplitude of vibrating body

If amplitude of vibrating body is large sound will be loud, if amplitude of vibrating body is small sound will be low. That is the reason why sound produced by sitar is loud if its wires are plucked violently.


Q: What is the relation between loudness and area of vibrating body?
Ans: 

Loudness ∞ Area of vibrating body

If area of vibrating body is large sound will be loud, if area of vibrating body is small sound will be low. The sound produced by large drum is louder than that by a small drum because of its large vibrating area.


Q: What is the relation between loudness and distance from vibrating body?
Ans: 

Loudness ∞ 1/Distance from vibrating body

If distance from vibrating body is large sound will be low, if  distance from vibrating body  is small sound will be loud. 


Q:  Differentiate between loudness and intensity?
Ans:
Loudness:
It is such a characteristic of sound by which a loud and a faint sound can be distinguished.
Loudness depends upon the physical condition of ear.
Loudness is measured in terms of sound level, whose units are bel and decibel.
Intensity:
Sound energy flowing per second through a unit area held perpendicular to the direction of sound waves is called the intensity of sound.

I = sound energy/ unit area

I = W/ m²

Intensity does not depend upon physical condition of ear.


Q: What is Weber Fechner Law?
Ans:  According to Weber's law

L ∞ log I

L = K log I

Where K is a constant of proportionality. L is loudness and I is intensity of sound.


Q: Define quality of sound?
Ans:  The characteristic of sound by which two sounds of same loudness and pitch are distinguished from each other is called the quality of sound. In figure below, sounds produced by tuning fork and piano have same loudness and pitch but their waveforms are different. So their quality is different and they can be distinguished from each other.

Q: What is the difference between noise and music?
Ans:  Such sounds which have pleasing effect on our ears are called musical sounds.
Sound which has jarring effect on  our ears is called noise.

Q: What are major sources of noise pollution?
Ans:  Auto vehicles, airplanes, helicopters, trains, heavy machinery, loud speakers are the major sources of noise pollution.


Q: What is the audible frequency range for human year?
Ans:  A human ear can hear a sound only if its frequency lies between 20Hz and 20,000Hz.


Q: Write two uses of ultrasonic?
Ans:  

1. The resources of oil and gas beneath the earth are searched by using ultrasonic.
2. The depth of an ocean can be measured by using ultrasonic.

Q:  What is meant by silent whistle?
Ans:   It is a whistle which has frequency in between 20,000 and 25,000Hz. This frequency is not audible for human ear so it is used to call the dogs because they can hear this range of sound waves.
Q:  Define ultrasonics?
Ans:   The sound waves which have frequency more than 20,000 Hz are called ultrasonics.


Q:   How depth of ocean is measured by means of ultrasonics?
Ans:    In measuring depth of ocean an ultrasonic pulse is sent down towards the ocean bed from the bottom of ship. This pulse after reflection from the ocean bed reaches the ship where it is detected. The time taken by the pulse of ultrasonic in reaching the bed and back to ship is noted, them using the formula S=vt, the depth (s) of the ocean is measured.

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Circular Motion And Gravitation

Q: Why value of g is less on mountains?
Ans:

 According to above equation if the distance (h) increases from the radius (R) of the earth the value of 'g' will decrease. This is the reason for less value of 'g' on mountain.

Q: On mountains our weight will be more of less?
Ans: On mountain our weight will be less due to decrease in value of 'g' with the increase in distance from earth.

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