Physics 10th Notes By Wasiq Bilal

Physics 10th Notes By Wasiq Bilal

In this blog we will be providing students with key notes which would be helping them out in solving their chapter's question and it would help the students to clear their concepts and get their work done in no time.

Physics Class 10th Notes by Wasiq Bilal

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    Saturday, 9 July 2022

    Chapter 14 : Current Electricity

    July 09, 2022 0
    Chapter 14 : Current Electricity

     Chp14 : Current Electricity

    Answer the following questions.

    1. Define the term Electric Current?

    Ans. “The rate of flow of electric charge through any cross-sectional area is called
    Electric current”
     Current  = Charge/ time         Or       I = Q/t
    Unit: SI unit of Current is Ampere (A).

    2. What is the difference between Electronic current and Conventional current?

     Ans.   Electronic Current
    The current due to motion of negative charges that flows from the negative terminal of the battery to the positive terminal in the electrical circuit is called Electronic current.

           Conventional Current
    The current due to motion of positive charges that flows from positive terminal of battery to its negative terminal is called Conventional current.

    3. How can we differentiate between e.m.f and Potential difference?

    Ans      EMF
    • Electromotive force is the total voltage in the battery.
    • Electromotive force is always greater.
    • EMF is only applicable to an electric field.
      
           Potential Difference
    • Potential difference is the work done in moving a charge against the electric field.
    • Potential difference is always small.
    • Potential difference is only applicable to magnetic, gravitational and electric field.

    4. Define Ohm’s Law?

    Ans.   If V is the potential difference across the two ends of any conductor, then current I
    will flow through it. The value of the current changes with the changes in potential
    difference and explained by ohm’s law.

    5. Define Resistance and its Units?

    Ans.  “The property of a substance which offers opposition to the flow of current through
    it is called its Resistance.”
    Unit :  Its SI unit is ohm

    6. Differentiate between insulators and conductors.



    7. Discuss the main features of Parallel combination of resistors?
    Ans: In parallel combination one end of each resistor is connected with positive terminal
    of battery while the other end of each resistor is connected with the negative terminal of
    battery.
    1/Req = 1/R1 + 1/R2 + 1/R3
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    Chapter 13: Electrostatics

    July 09, 2022 0
    Chapter 13: Electrostatics

         Chp 13: Electrostatics

    Answer the following questions.

    1. How can you show by a simple experiment that there are two types of charges?

    Ans.  Experiment at pg 69

    2. Describe the method of charging through electrostatic induction?

    Ans. There are a variety of methods to charge an object. One method is known as induction. In the induction process, a charged object is brought near but not touched to a neutral conducting object. The presence of a charged object near a neutral conductor will force (or induce) electrons within the conductor to move.
    Take two insulator conductors or neutral bodies fixed on a stand and bring a postively charged rod near to it eventually it will attract the unlike charges causing the negative charge to come near to rod while the like charge i.e the positive charges will move at the opposite end of the bodies.

    3. What is Gold leaf electroscope? discuss its working principle with the help of a diagram. 

    Ans.  “The gold leaf electroscope is sensitive instrument for detecting charges”.
    Working:  
     Electroscope consists of closely placed two metallic (aluminium) foils or strips. When both the strips are charged with similar charges, they repel each other and become wide on

    4.  With the help of electroscope how can you find presence of charge on the body?

    Ans.  pg 72 (In order to detect ........... amount of charge on the body)

    5.How can you find the nature of charge on the body?

    Ans.   pg 72  ( for the detections of charge....................  the body has negative charge)

    6. Explain Coulomb’s law of electrostatics and write its mathematical form?

    Ans. “The force of attraction or repulsion between two point charges is directly
    proportional to the product of the magnitude of charges and inversely proportional to the
    square of the distance between them”.
    Mathematically :
    Mathematical form: If there are two point charges q1 and q2, separated by a distance (r),
    then the electrostatic force F between the charges.
    F ∝ q1 q2
    Force ∝ 1/ d2
    F = k q1q2/ d2

    7. What is meant by Electric field and Electric intensity?

    Ans.    Electric field :
    The electric field is a region around a charge in which it exerts electrostatic force on another charges.
           Electric field Intensity:
    The strength of electric field at any point in space is known as electric field intensity.

    8. What is difference between variable and fixed type capacitor?

    Ans.   A fixed capacitor is constructed in such manner that it possesses a fixed value of
    capacitance which cannot be adjusted. While in variable type of capacitors some
    arrangement is made to change the area of the plates facing each other.

    9. Enlist some Uses of capacitors?

    Ans.  Uses of Capacitors:
    • Capacitors are used for tuning transmitters, receivers and transistor radios.
    • Capacitors are used in electronic circuits of computers.
    • Capacitors are used to differentiate high and low frequency.

    10. Derive the formula for the equivalent capacitance for a series combination ofa number of capacitors?

    Ans: In this combination, the capacitors are connected side by side..    
    V = V1 + V2 + V3
    V = Q/C1 + Q/C2+ Q/C3
    V = Q(1/C1 + 1/C2 + 1/C3)
    V/Q = 1/C1 + 1/C2 + 1/C3
    1/ Ceq =   1/C1 + 1/C2 + 1/C3

    11. Define the hazards of electricity ?

    Ans .    pg 85 both heading imp

    12. How would you define Potential difference between two points? Define its unit.

    Ans.  Potential difference between two points becomes equal to the energy supplied by
    the charge. Thus, we define potential difference between two points as the energy supplied by a unit charge as it moves from one point to the other in the direction of the field.
    Unit: Unit of potential difference is Volt.

    17. What do you mean by the Capacitance of a capacitor? Define units of capacitance.

    Ans. Capacitance of capacitor is defined as “the ability of the capacitor to store charge”.
    It is given ratio of charge and the electric potential as:
              C = Q/V
    Unit: SI unit of capacitance is farad.
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    Chapter 12 : Geometrical Optics

    July 09, 2022 0
    Chapter 12 : Geometrical Optics

                  Chp12 : Geometrical Optics

    Answer the following questions.

    1.  What do you understand by Reflection of light? Draw a diagram to illustrate reflection at a plane surface.

    Ans.  “When light travelling in a certain medium falls on the surface of another medium, a
    part of it turns back in the same medium, this is called Reflection of light”. 


    2.  Describe the following terms used in Reflection:

    Ans. a) Normal:
    The imaginary line perpendicular to the reflecting surface of mirror at the point of incidence is called Normal.

      b) Angle of incidence:
    The angle between the incdent ray and the normal is called angle of incidence.

      c) Angle of reflection :
    The angle between the reflected ray and normal is called angle of reflection.

    3.  State Laws of Reflection? 

    Ans. Following are the laws of reflection :
    • The incident ray, reflected ray and normal at the point of incidence lie in the same pane.
    • The angle of incidence is equal to the angle of reflection.

    4.  Define Refraction of Light?

    Ans. “Bending effect of light as it passes from one transparent material into another is
    called Refraction of light”.



    4. Define the following terms used in refraction:

    Ans.  Angle of incidence:
    The angle that the incident ray makes with the normal is referred as the angle of incidence. 
            Angle of refraction:
    The angle that the refracted ray makes with the normal line is referred to as the angle of refraction.

    5.  What is meant by Refractive index of a material?How can it be determined ?

    Ans.  When a ray of light passes from one particular medium to another, the ratio of the
    sin of the angle of incidence to the sin of the angle of refraction is constant. This constant
    ratio is called the refractive index. 
         n = Sin i/Sin r

    6.  What is meant by the term Total Internal reflection? 

    Ans.  The angle of incidence for which the angle of refraction becomes 90 is called
    critical angle. When the angle of incidence becomes larger than the critical angle, no
    refraction occurs. The entire light is reflected back into the denser medium. This is known
    as Total Internal reflection.

    7.  State the Laws of Refraction of Light?

    Ans.  Following are the laws of refraction given below :
    •  The incident ray, the normal, and the reflected ray at the point of incidence all lie in the same plane.
    • For two particular media, the ratio of the sin of the angle of incidence to sin of the angle of refraction is a constant.

    8.  State the conditions for Total Internal reflection?

    Ans. Conditions for total internal reflection are:
    • The ray of light passes from denser to a less dense medium.
    • The angle of incidence in the denser medium is greater than the critical angle

    9. What is Critical Angle? 

    Ans.  “The critical angle is defined as the angle of incidence in the optically denser
    medium for which the angle of refraction in the less dense medium is 90 °”

    10. What are Optical Fibers? Describe how total internal reflection is used in propagating of light through optical fibre ?

    Ans.   An optical fibre cable is a bundle of glass fibres with thickness of a human hair.                                         Working of Optical Fibre:

    pg 45 (from Total internal reflection is used in optic fibre..............................  with small loss of energy).

    10.  Define the following terms applied to a lens:

    Ans.  (i) Principal axis:
    Each of the two surfaces of a spherical lens is a section of a sphere. The line passing through the two centres of curvatures of the lens is called Principal axis.
              
             (ii) Optical centre:
    A point on the principal axis at the centre of lens is called Optical centre.

             (iii) Focal length:
    The focal length is the distance between the optical centre and the principal focus

    11.  What is meant by the Principal focus of a:

    Ans.  Principal focus of Convex lens:
    The light rays travelling parallel to the principal axis of a concave lens after refraction meet at a point on the principal axis called principal focus or focal point. Hence convex lens is called converging lens.

           Principal focus of Concave lens:
    The parallel rays appear to come from a point behind the lens called principal focus. Hence concave lens is also called diverging lens.

    12. Describe how light is Refracted through Convex lens?

    Ans.   Refraction of light through convex lens can be described with the help of three
    principal rays as:
    • The ray parallel to the principal axis passes through the focal point after refraction by the lens.
    • The ray passing through the optical center passes straight through the lens and passes deviated.
    • The ray passing through the focal point becomes parallel to the principal axis after refraction by the lens.

    13. A coin is placed at a focal point of a converging lens. Is an image formed? What is its nature?

    Ans.  A coin is placed at a focal point of a converging lens. No image is formed because
    the refracted rays are parallel and never meet. 


    14.What are the Differences between Real and Virtual Images?

    Ans.   Real Image
    • Real image usually appear inverted.
    • On mirror, Real images lie in front of the reflecting surface.
    • On lens, Real images lie on the other side of the object.
    • Light rays meet at a focal point in front of the mirror.
              Virtual Image
    • Virtual image usually appears erect.
    • Virtual image cannot be obtained on screen.
    • On lens, Virtual images lies on the same side of the object.
    • Light rays meet at a focal point behind the mirror.

    15. How does a converging lens form a virtual image of a Real object? How does a diverging lens can form a real image of a Real object?

    Ans.   At pg 50 and 51

    16. Define Power of a lens and its Units?

    Ans.  “Power of a lens is defined as the reciprocal of its focal length in metres”
     Unit :    SI unit of power of a lens is dioptre denoted by a symbol D.

    16.   Define the terms Resolving Power and Magnifying Power?

    Ans,   Resolving Power:
    Resolving power of an instrument is its ability to reveal the minor details of the object under examination.

          Magnifying Power:
    The ratio of the angles subtended by the image as seen through the optical device to that subtended by the object at the unaided eye.


    17.  What is meant by the terms Nearsightedness and Farsightedness? How can
    these defects be corrected?

    Ans. Nearsightedness (myopia): “Some people cannot see distant objects clearly
    without the aid of spectacles. This defect of vision is known as Short sight or
    Nearsightedness”.
    Correction of Nearsightedness: The nearsighted eye can be corrected with glass or
    contact lenses that use diverging lenses.

    Farsightedness (hypermetropia): “The disability of the eye to form distinct images
    of nearby objects on its retina is known as Farsightedness”.
    Correction of Farsightedness: Farsightedness can be corrected with the aid of a
    suitable converging lens.

    18. Draw Ray diagrams.

    Ans.   pg 50,51

    19. Mention magnification for telescope, microscope and  simple microscope?

    Ans.  pg 58,56,57
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    Thursday, 7 July 2022

    Chapter 11 : Sound

    July 07, 2022 0
    Chapter 11 : Sound

                        Chp11 :  Sound

                                 Exercise Questions

    Answer the following questions.

    1. What is necessary condition for the production of sound?

    Ans. Unlike light waves which are electromagnetic in nature and also can pass through vacuum,sound waves require some material medium for their propagation because it is mechanical wave.

    2. What is the effect of the Medium on the Speed of Sound? In which medium sound travels faster: air, solid or liquid?

    Ans. The nature of the medium will affect the speed of the sound waves. Sound will travel faster in solids as the particles of solid are tightly packed .Speed of sound in air is fifteen times greater than in gas while sound has five times greater speed in liquid than in gas. 

    3. How can you prove the mechanical nature of sound by a simple experiment?

    Ans.  Take an electric bell suspended in a bell jar with the help of two wires connected to power supply.By setting on power supply,electric bell will start ringing. Now start pumping the air out of the bell jar eventually the sound of electric bell will die out but if you pump back the air into the jar so again you will be able to hear the electric bell. This experiment of bell jar proves the mechanical nature of sound.

    4.What do you understand by the longtudinal wave? Describe the longituinal nature of sound.

    Ans. In longitudinal waves, the particles of medium move back and forth along the direction of the propagation of the waves
     Longitudinal Nature of Sound:
    Direction of propagation of sound waves along oscillation or vibrating molecules.This shows the longitudinal nature of sound waves.

    5. Sound is a form of wave.List some reasons to prove that sound is a wave.

    Ans. Sound is form of wave, following are the reasons given below:
    • It is produced by vibration of particles of medium
    • Its is a carrier of energy
    • Sound also manifest the phenomenon of diffraction, refraction and reflection.


    6. We know that wave manifest the phenomenon of diffraction, relflection and refraction. Does sound also show these properties of waves?

    Ans. Yes, like other waves sound also manifest the phenomenon of diffraction, relflection and refraction.

    7. What is the difference between the intensity and loudness? Describe relation between the two terms.

    Ans.  Intensity:
    “Sound energy passing per second through a unit area held perpendicular to the direction of propagation of sound waves”. The basic units are (Wm-2).
            Loudness: 
    “Loudness is the characteristic of sound by which loud and faint sounds can be distinguished”.
                               Relation between intensity and loudness
                       L - Lo = K (log I – log Io) = K log I /Io

    8.  On what factors does the loudness of sound depend?

    Ans. Loudness depends upon following factors:
    • Area of vibrating body
    • DIstsnce from vibrating body
    • Amplitude of vibrating body


    9. What do you mean by the term Intensity level of the sound? Name and define the unit of intensity level of sound.

    Ans. As we know
                                    L - Lo = K (log I – log Io) = K log I /Io

    The difference (L - Lo) between the loudness (L) of an unknown sound and the
    loudness Lo is called the intensity level of the unknown sound.
    There are two unit of intensity level of sound: Bel and deciBel (dB)

    10. What is difference between Frequency and Pitch?

    Ans.  “Frequency is the number of occurrences of a repeating event per unit time” While
    “Pitch of the sound is a characteristic of sound by which a shrill sound can be
    distinguished from a grave one”.

    11. Describe the effect of change in amplitude on loudness and the effect of change in frequency on pitch of sound.

    Ans. The loudness of the sound varies directly with the amplitude of the vibrating
    body. Higher amplitude has more loud sound.
    Pitch of the sound varies directly with the frequency. A higher pitches means higher
    frequency and vice versa.

    12.Explain that Noise is a Nuisance?

    Ans. “A noise nuisance is an annoyance or a noise that is audible”.
         Impacts of Noise:
    The impact of noise on human health is a matter of great concern.
    Noise pollution can affect us in several ways: Hearing problems, Poor cognitive function,
    cardiovascular issues, Sleep disturbance, Trouble communication and Mental health
    problem.

    13. If the pitch of sound is increased, what are the changes in following:

    Ans.    a) the frequency
    As pitch is directly proportional to frequency hence the the increase in pitch will cause an increase in the frequency as well.
                b) the wavelength
    With the increase in pitch there will be a decrease in wavelength.
                c) wave velocity
    The  increase of pitch will cause an increase in wave velocity.
                d) amplitude of wave
    The increase of pitch will have no effect on amplitude.


    14. If we clap or speak in front of a building while standing at a particular distance, we rehear our sound after sometime. Can you explain how does this happen?

    Ans. It is due to reflection of sound. When the sound is incident on the surface of the other medium it bounces back into its first medium which is known as relfection of light.

    15. What is the Audible frequency range for Human Ear? Does this range vary with the age of people? Explain.

    Ans. “The range of the frequencies which a human ear can hear is called the Audible
    frequency range”.
    A normal human ear can hear a sound only if its frequency lies between
    20Hz and 20,000Hz.Different people have different range of audibility. It also decreases
    with age. Young children can hear sounds of 20,000 Hz but old people cannot hear
    sounds even above 15,000 Hz.

    16.  Describe the importance of Acoustic Protection?

    Ans.  Acoustic has a great importance in our daily life.
    • Office equipment’s has increased significantly, the noise level remained almost the same.
    • Productivity increases when the noise level decreases at the work place.
    • Indoor environment of all places of work must ensure that people feel healthy both in mentally and physically terms. 


    17. What are the uses of ultrasound in medicines ?

    Ans. Some few uses of Ultrasound in Medicine are:
    • Ultrasound is used to diagnose and treat different ailment.
    • Ultrasounds are used to help a doctor to evaluate the flow of blood in the vessels.
    • The heart can also be studied by using an ultrasound.
    • Ultrasound is a helpful way to observe many of body’s internal organs.
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    Chapter 10: Simple Harmonic Motion

    July 07, 2022 0
    Chapter 10: Simple Harmonic Motion

               Chp10 : Simple Harmonic Motion

                                         Exercise Questions

    Answer the following questions.

    1.What is Simple Harmonic Motion? What are the necessary conditions for a body to execute simple harmonic motion? 

    Ans.  Simple Harmonic Motion is the to and fro oscillatory motion in which acceleration of the body is directly proportional to displacement of body from mean position and is always directed towards the Mean position. 

    Necessary Conditions:

    • A body executing Simple Harmonic Motion  always vibrates at a fixed position.
    • Its acceleration is always directed towards mean position
    • The magnitude of acceleration is always directly propotional to its displacement from the mean position i.e acceleration will be zero at mean position while it will be maximum at extreme position
    • Its velocity is maximum at the mean position and zero at the extreme position
    • Kinetic Energy is maximum at mean position an zero at extreme position while Potential Energy is maximum at extreme position and zero at mean position.

    2. Think of several examples of motion in everyday life that are simple harmonic.

    Ans. Common Examples of Simple Harmonic Motion are:
    1. Motion of Simple Pendulum
    2. Up and Down Motion of cork in water
    3. Motion of body in swing

    3.What are damped oscillations. How damping progressively reduces amplitude of oscillations?

    Ans.  Any oscillation in which the amplitude of the oscillating quantity decreases with time is called damped oscillation.

    Damping Reduces Amplitude :
    Practically in all system the force of friction and resistance retards the motion, so the system do not oscillate for long time period. Friction reduces mechanical energy of a system as time passes. Due to this reason Damping progressively reduces amplitude of oscillations.

    4. How can you define the term wave? Elaborate the difference between mechanical and electromagnetic wave.Give example of each.

    Ans. Wave :
            A wave is the disturbance in the medium causing the particles of the medium to undergo vibratory motion and it carries energy from one place to another.
    Mechanical Waves :
    Def. Waves that require a medium for its propagation are called mechanical waves .
    Example: Sound waves
    Electromagnetic Waves:
    Def. Waves that do not require a medium for its propagation are called electromagnetic waves.
    Example: Light waves

    5. Distinguish between longitudinal and transverse waves with suitable example.

     In Longitudinal Waves,  The vibratory motion of particles is parallel to direction of propagation  of waves .It consists of Compression and Rarefractions.   E.g  Sound Wave, While     In Transverse Waves,  The vibratory motion of particles is perpendicular to direction of propagation  of waves.It consists of crests and trought.    E.g Light wave 

                                                       

    6. Derive a relationship between velocity, frequency and wavelength of a wave.

    Ans.    Velocity = distance/time
                v =    d/t
                 v=      λ /T

                    ∵f= 1/T

    hence,    v = f λ   

        

    7. Define Spring Constant. Write its formula also?      

    Ans. K is a constant called the spring constant. The value of K is a measure of the stiffness of the spring.            Formula:        K = -  F/X


    8.      Explain the following properties of waves with reference to ripple tank experiment.  

    Ans.           Reflection: When waves moving in one medium fail on the surface of another medium they bounce back into the first medium such that the angle of incidence is equal to the angle of reflection.  

                       Refraction: When a wave from one medium enters in the second medium at some angle, its direction of travel changes is called Refraction.   

                       Diffraction: The bending or spreading of waves around the sharp edges or corner of obstacles or slits is called Diffraction.

        

    9. Does increasing the frequency of a wave also increase its wavelength? If not, how are these quantities related?

    Ans. No, increasing the frequency will not increase the wavelength as both the quantities are inversely proportional to each other. Hence increasing the frequency will cause a decrease in the wavelength.


    10. Draw a wave with an amplitude of 2cm and a wavelength of 4cm. Label crest and trough on wave.                                                                                                                                                                   Ans.


                                                           

                                                                                      
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