best Solution of all Chapter of class 10th federal board students download in pdf, National book foundation 10th physics notes 10th Physics Conceptual Questions Notes By Sir Ijaz Ali (BS Mathematics & Physics )
10th Class Physics Notes by Classic Study Evening Coaching
Conceptual Questions Physics chapter 10
Q10.1: Ans: since T=
When the length is doubled we put .the new time period will be T new
T new =
T new =
(Taking
as common from under root)
T new = T
So, if we double the length of the simple pendulum the time period increases by Time of the original time period.
Q10.2: Ans: No, because SHM requires a restoring force and acceleration to be proportional to the displacement of the object, but the bouncing ball has constant force and acceleration regardless of the displacement, moreover its mean position is also not fixed.
Q10.3: Ans: There is not effect on the time period because as we know the formula of the time period of simple pendulums:
T=
As there is no mass included in the formula of time period, so time period remain the same by changing the mass of the pendulum keeping the other parameters constant.
Q10.4: Ans: Electromagnetic waves do not require any medium for their propagation such as radio waves, heat waves, light waves etc.
Q10.5: Ans: water waves travel faster when the medium is deepest. Thus if water waves are passing from deep water into shallow water, they will slow down (speed Decreases) and also the wavelength of the plane waves shortens (waves length decreases)
Conceptual Questions Physics chapter 11
Q.11.1: Ans: When two tin cans are attached with a stretched string then the string becomes a medium that transmit sound waves from one can to the other. String is a solid and solids are better medium of transfer of sound waves than air which is a gas. When we shout in air then air carries sound with low speed than a stretched string because sound travels five times faster in solids than in gases.
Q.11.2 Ans: We can recognize persons speaking with the same loudness from their voice because quality of sound is different. Quality of the sound is the characteristic by which we can distinguish between two sounds of same loudness and pitch. The wave forms of sound produced by persons are different. So their quality is different and they can be distinguished from each other.
Q.11. 3Ans: Wavelength of sound waves is large than wavelength of light waves, so sound of our friend can be diffracted and easily heard by us. However light waves have small wavelength and cannot be diffracted. This makes it impossible for us to see our friend around a corner.
Q.11.4 Ans: In carpeted floor rooms, volume of stereo has to be tuned higher because carpet is made up of softer material than wood and according to acoustics the reflection of sound is less if the reflecting surface is soft and porous.
Q.11.5 Ans: No, the statement of the student is not correct. Speed is the distance travelled by wave in unit time, whereas frequency is the number of waves passing from any surface in one second. So these two things are not same. Also frequency does not depend upon the nature of the medium but the speed of the waver is different in different mediums.
Q.11.6 Ans: This may happen only due to difference in the hearing sense of the two persons. A sound appears louder to the person with sensitive ears than to a man with defective ears.
Q.11.7 Ans: No, there is no difference between echo and reflection of sound. Echo can be defined as when sound is incident on the surface of a medium, it reflects back into the first medium. This phenomenon is also called reflection.
Q.11.8 Ans: No, two separate 50dB sounds do not constitute 100dB sound because dB is an exponential scale and each 10 dB increase in sound makes the sound 10 times louder. An increase of 50dB scale will make sound 104 times louder. Hence it will not make 100dB but twice as loud as increase of 10Log (2) = 3.01dB is twice as loud as 50dB.Mathematically, we know that
If intensity level = 50dB Io = 10-12 I=?
50 = 10 log ( I/10-12)
5 = log (I/10-12)
Anti-log 5= I/10-12
105 x 10-12 = I
So, I = 10-7 Wm-2
If we add them I+I = 2I =2 10-7
Reconverting into dB scale, we get
Intensity level = 10 Log (I/Io)
=10 Log (2x 10-7 / 10-12)
=10 Log (2x 10-7/ 10-12)
=10 Log (2 x 105)
=10 (Log2 + Log 105)
=10 (0.3010+ 5 Log 10)
=10 (0.3010+ 5(1))
=10 (0.3010+ 5)
=10 (5.3010)
=53.010 dB Proved
Q.11.9 Ans: The wavelength of ultra sound waves is shorter is shorter as compared to normal sound waves. Because of these ultra sound waves are reflected back by the obstacles in their path rather than bending round. This quality of ultra sound makes it useful in many fields including medical field.
The ultra sound techniques are more advantageous than X-Ray for obtaining images of internal organs.
Q.11.10 Ans: No, we will not be able to hear any sound because moon has no atmosphere, there is vacuum on the surface of the moon, and propagation of sound waves require material medium for its propagation.
Conceptual Questions Physics chapter12
Q.12.1 Ans: A man raises his left hand in a plane mirror, the image facing him raises his right hand. This is due to lateral inversion (It is the effect produced by mirror reversing images from left to right). Plane mirror is the only type of mirror which always gives us virtual & erect image of the same size as that of the object.
Q.12.2 Ans: Refraction occurs at the boundary of two mediums, when light travels from one medium to another medium its speed changes but frequency remains the same. If the light hit the medium at an angle which is not perpendicular to or parallel to the surface, then it will change its direction and appear to bend. The amount of bending depends upon the index of refraction of the two mediums.
Q.12.3 Ans: Since the air is rarer medium so angle of refraction is greater than angle of incidence. For an observer’s eye, the object appears to be raised up above the actual position due to which apparent depth of the pond look less than its real depth i.e. it appears to be shallower.
Q.12.4 Ans: People use concave mirror for make-up because when a person stands between the principal focus and pole of the mirror, person sees an enlarged, erect and virtual image of his face. This is the reason why concave mirrors of large focal length are used for make-up.
Q.12.5 Ans: Drivers side mirror is convex because they always produce erect image of the objects behind driver, moreover the field of view is very broad and the driver is able to see more widely. However, plane or convex mirror will not make erect image all the time and also will not give a broader view.
Q.12.6 Ans: To increase the distance of eye chart from the patient, the optician uses plane mirror in small rom. This tricks the eye and makes the space seem larger. The eye chart seems to be at double distance than it originally is.
Q.12.7 Ans: The focal length of the lens is inversely proportional to the thickness of the lens, when the thickness of the lens increases, its focal length decreases and vice versa.
Q.12.8 Ans: Converging lens (convex lens) forms virtual images if the object distance is less than the focal length. If the object is in between the principal focus and the optical centre then the image formed will be virtual. This image will be behind object, virtual, erect and larger than the object.
Q.12.9 Ans: When the object is placed at 2F then the real & inverted image is formed at the other side of the lens having the same size.
Q.12.10 Ans: The magnification of the telescope is given by M= fo/fe. So, it is clear that objective lens of larger focal length givers greater magnification of telescope is directly proportional to the focal length of objective lens.
Conceptual Questions Physics chapter 13
Q 13.1 Ans : Initially the pieces of paper are attracted due to electrostatic induction so they are attached with rod . After attaching they attain the same charge so they fly off .
Q 13.2 Ans : the same jmu 7.5 x 10-11C negative charged is removed .
Q 13.3 Ans: the electric field lines are supposed to be directed from positive to negative charge. So when a positive charge is placed in such electric field, it will move away from the field
Q 13.4 Ans : yes , in series combination of each capacitor carry equal charge due to electrostatic induction , one type of charge at one plate will induce the same quantity of opposite charge on the other plate
Q 13.5 Ans : as the capacitors are not connected in parallel to each other but also with the battery as well . So in parallel circuit same potential is developed in all electrical components as that of battery therefore each two plates in parallel combination of capacitors will have same potential
Q 13.6 Ans : a metallic chain can be seen hanging from the rear side of a gasoline truck this chain rolls on the road as the tanker moves due to fraction with air the body of tanker gets charged and tiny spark can cause a havoc this charge is continuously being transfer to ground metallic chain thus the danger of apart is eliminated
Q 13.7 Ans : If a high voltage power line fell across the car while the person is in the car , the supply is actually grounded while passing through the body of the car and when the person will try to come out of the car , electrification may happen through the person to get grounded d which is hazardous for the person. Moreover the tires are good insulators so person will be safe inside the car rather than outside.
Q 13.8 Ans :Iron rod is good conductor . Charge after rubbing will not accumulate on the surface whereas glass rod is an insulator charge will not flow inside it after rubbing and will accumulate on its surface.
Conceptual Questions Physics chapter 14
Q 14.1: Ans: In conductor there are majority of free electron which can easily flow from one place to another place while the positive charges remain stationary at their respective position that is why charge is transfer by free electron rather than by positive charge.
Q 14.2: Ans:
| CELL | BATTERY |
| A small compartment of electricity is called cell. The output voltage of cell is fixed i.e. 1.5V.Cell is always dry. | Battery is a group of large number of cells.The output voltage of battery depends upon number of cells it contains e.g. 6V battery contains 4 cells each having 1.5 V.Battery may be dry or it may contain liquid. |
Q 14.3 Ans: yes. to flow the current through a circuit potential difference is necessary otherwise no current can flow.
Q 14.4: Ans: Yes, The flow the charges between the two points of an object are only possible if there is some potential difference between these points. If there is no potential difference, no current will flow.
Q 14.5: Ans: The resistance of ammeter is kept low so that maximum current can flow through if it is connected in series in the current, in this way an accurate value of current can be measured.
Q 14.6: Ans: The resistance of volt meter is kept high so that maximum voltage can drop across the resistance if it is in connected in parallel to the potential source in a circuit.
Q 14.7: Ans: We know that 1 kwh = 36 x 105 J and 1 Wh = 3600 J
1wh=3.6×103 J
1wh/3.6×103=1J
1J=0.00027wh
1000J=1000×0.00027wh
=0.27wh
Q 14.8: Ans: Automobile head lights are connected in parallel with the battery to get maximum voltage. Because the battery is also providing the voltage to the other electrical parts of the automobile at the same time. In case of series circuits the head lights may get dim. Moreover if one lamp gets defective other will continue to glow because it is connected in parallel.
Q 14.9: Ans: Low resistance means high current which means battery will discharge quickly . Low resistance of 5 ohm gives brighter light because it offers low resistance and more current can flow through the circuit. So more brightness will be with 5 ohm and same will discharge battery first.
Q 14.10: Ans: if we connect electric bulb and heater in series this divides the voltage supply through each appliance is affected. In order to avoid this loss of power they are connected in parallel.
Q 14.11: Ans: The fuse in circuit control only the current therefore it is connected in series with the live wire. When current exceeds the limited value the fuse wire melts and stops the current by breaking circuit.
Conceptual Questions Physics chapter 15
Q15.1: Ans: We will bring the compass needle near each of the bars . The iron bar which is not the magnet will not cause any deflection of the needle in the compass.
Q15.2: Ans: by moving the bar magnet toward the coil or by moving the coil toward the stationary magnet, the induced e.m.f and induced current as well can be produced in the coil. this induced current will produced due to charge in the magnet flux through the coil.
Q15.3: Ans: Electric motor is use to convert electrical energy into mechanical energy.
Q15.4: Ans: the coil will swing perpendicular to its cross-sectional area due to opposite polarity of magnet and coil according to Len’s law.
Q15.5: Ans: The conductor wire should move perpendicular to direction of magnetic field lines to produce a maximum induced voltage in it according to right hand rule.
Q15.6: Ans: Generator converts mechanical energy in to electrical energy and motor converts electrical energy into mechanical energy.
Q15.7: Ans: In case of D.C motor the direction of electric current is reversed due to split ring commutator .
Q15.8: Ans: By applying right hand rule the wire will move down perpendicular to the direction of magnetic field and current.
Q15.9: Ans: No, a transformer can operate only on A.C because it operates on the principal of mutual induction which is obtained prominently in A.C supply.
CONCEPTUAL QUESTION CHAPTER 16
16.1: Factors that enhance thermionic emission are:1) Magnitude of the charge flow increases with increasing temperature.
2) The nature of the substance used as filament because different materials have different number of free electrons.
3) Area of the metal.
16.2: The cathode rays are negatively charged which is evident from the following examples.
1. The cathode rays are deflected and accelerated towards the positively charged plates.
2. Cathode rays are negatively charged particles because they are deflected by magnet in just the same way as moving negatively electrified particles.
3. Cathode ray tube having Faraday’s cylinder anode connected to an electroscope’s plate show negative charge on the gold leaves of electroscope. This can be observed by the divergence of gold leaves when a charged rod is brought near the electroscope plate. This experiment is also evident that cathode rays are negatively charged.
16.3: Electrons are deflected towards the positively charged plate. It clearly indicates that cathode rays are negatively charged particles which are attracted and deflected towards positively charged plate.
16.4: Factors that affect the divergence of cathode rays by magnetic field:1.The intensity of the magnetic field. More is the intensity of the magnetic field, more is deflection force.
2. The angle between magnetic lines of forces and the moving electrons.
16.5: The truth table of logic operation X= A.B of AND gate in binary form is obtained as in below table when either of the input or both the output is ‘0’. When both the inputs are closed (0).The output is closed.
| A | B | X=A.B |
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
The outcome of inputs in all columns is exactly the same as the multiplicative product of the inputs A and B.
16.6: NAND gate is the reciprocal of AND gate. In NAND gate’ the value of AND gate is inverted by NOT gate from the sets of inputs and outputs given in truth table of NAND gate it is clear that it is reciprocal of AND gate in every time the value of output of AND gate is inverted.
| A | B | |
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
AND GATE: NAND GATE:
| A | B | X=A.B |
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
16.7:
Y A
B
The circuit acts as an OR gate because in the circuit the output terminal of NOR gate is coupled with NOT operation. In NOR gate, the value of OR gate is inverted, then followed by NOT operation, the value of OR gate is regenerated as in below truth table.
| A | B | A+B | | |
| 0 | 0 | 0 | 1 | 0 |
| 0 | 1 | 1 | 0 | 1 |
| 1 | 0 | 1 | 0 | 1 |
| 1 | 1 | 1 | 0 | 1 |
16.8:
A
Y
B
| A | B | ||||
| 0 | 0 | 1 | 1 | 1 | 0 |
| 0 | 1 | 1 | 0 | 1 | 0 |
| 1 | 0 | 0 | 1 | 1 | 0 |
| 1 | 1 | 0 | 0 | 0 | 1 |
In this circuit NOT operation is working as input of terminals of NOR gate from above truth table it is clear that this circuit acts as AND gate (truth table given below )
AND gate:
| A | B | X=A+B |
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
Conceptual Questions Physics chapter 17
Q 17.1: Ans: In optical fiber information travels in the form of light signals, through the core of FO cable, by total internal reflection. Therefore negligible data is lost due to absence of any interference source such as heat, air dampness, electric / magnetic interference, etc. Secondly a large amount of data, at a highly faster rate can be transmitted via FO cables.
Q 17.2: Ans: Hard disk is more reliable than floppy disk in ways such as:
- Hard disk has much more storage capacity (in GBs & TBs) while floppy disk has storage capacity of few MBs.
- Data accessing and transfer is much faster with hard disk as compared to floppy disk.
- External casing of hard disk is much better as compared to that of floppy disk, to protect from external dirt and dust. Such casing also makes hard disk less vulnerable to external electric/magnetic field, in comparison to floppy disk.
Q 17.3 Ans:
| RAM | ROM |
| Random Access Memory. RAM temporarily stores data require by computer programs to execute specific command / task. RAM is volatile, means all data it contain shall be lost in case power supply to system is cut off. Types: SRAM, DRAM | Read Only Memory. ROM is used to store program instructions require to boot computer system. ROM is non-volatile and keeps the contained data even if power is switched off. Types: PROM, EPROM, EEPROM. |
Conceptual Questions Physics chapter 18
Q 18.1 Ans: Yes, it’s possible for an element to have different type of atoms. Such atoms are called isotopes of that particular element. Each atom has same atomic number, means same number of protons in their nuclei but different atomic masses due to different number of neutrons in their nuclei.
Q 18.2: Ans: In each fusion event 25.7 MeV energy is released while in each fission event about 200 MeV of energy is released. Hence it is clear that in fission reaction much more energy is released in comparison to fusion reaction.
Q 18.3: Ans: α-particles have double +ve charge and has highest tendency to interact with the matter it passing through, to ionize it. Thus having least penetration power.
β-particles are high energy electrons with –ve charge, hence can interact with surrounding matter, have penetration power greater than α rays.
γ-rays are fast moving light photons and due to their neutral nature and shorter wavelength, has least tendency to react with surrounding matter and therefore has highest penetrating power.
Q 18.4: Ans:
| Natural Radioactivity | Artificial Radioactivity |
| Naturally available radioactive elements whose unstable nuclei emit radiations to become stable. Elements having atomic numbers > 82, e.g. Uranium, Radium, Cobalt.Have half life cycles with duration spanned over several 1000 years. | Stable elements which when bombarded with α, β or neutrons are artificially transformed into radioactive isotopes to emit radiations.Radioisotopes of stable elements having atomic numbers < 82, e.g. Sodium, Nitrogen, Phosphorus.Have half life cycles of short duration. |
Q 18.5 Ans: No, theoretically it is impossible to predict when a radioactive element shall completely decay. Reason is that decay activity follows exponential law and half-lives of most radioactive elements span over several thousand years. So witnessing such activity within human life span is impossible.
Q 18.6: Ans: In gamma decay an unstable nucleus in excitation stage, stabilize itself by releasing excitation energy, thus keeping its atomic number and atomic mass remain unchanged.
ZXA* →→ ZXA + γrays
27Co60* →→ 27X60 + 0γ0+ Energy
Q 18.7: Ans: Amount of sample = 1 g.
Amount of sample left after 1 Half-life T1/2 = 1/2 = 0.5 g
Amount of sample left after 2 Half-live 2T1/2 = 0.5/2 = 0.25 g
Amount of sample left after 3 Half-live 3T1/2 = 0.25/2 = 0.125 g
Amount of sample left after 4 Half-live 4T1/2 = 0.125/2 = 0.0625 g
Q 18.8: Ans: The stated activity is β decay, as follows.
ZXA →→ Z+1YA + -1e0+ Energy
1H3 →→ 2H3 + -1e0+ Energy
Daughter nucleus will be an isotope of Helium-3.
Q 18.5 Ans: 7N14 is an isotope of nitrogen. It has seven numbers of protons and seven numbers of neutrons in its nucleus. 7N16 differs from 7N14 in a way that it has same number of protons in its nucleus but have two extra neutrons in its nucleus and hence its atomic mass has increased by 2.
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