10th Science Most Important Repeated Concepts
Passing Package
For Below Average Students
Physics
Electricity
→ SI Units
★ Electric Current (I) = Ampere (A)
★ Electric Charge (Q) = Coulomb (c)
★ Electric Power (P) = Watt (w)
★ Potential difference / Voltage (V) = volt (V)
★ Resistance (R) = Ohm (Ω)
★ Resistivity = ohm mete (Ω m)
→ Electric Components Symbols
→ Voltmeter
★ It measure the voltage
★ It Connected in parallel
→Ammeter
★ It measure the current
★ It connected in series
→Electric current
★ Flow of electric charge through conductor.
Or I = Q/t
→Define 1A
★ 1A = 1 c / 1 s
→Potential difference
★ Work done to moving electric charge.
Or V = W / Q
→Define 1V
★ 1V = 1 J / 1 c
→ Resistance
★ Oppose the flow of current.
→ Resistance of the conductor depends on
★ length
★ Thickness
★ Materials
★ Temperature
→ Ohm's law
★ Voltage directly proportional to current.
Or V = IR
→ Joule's law of heating
★ Heat produced in conductor directly proportional to
(i) current (ii) resistance (iii) time
Or H = I2Rt
→ Advantages of Parallel Connection
★ If one device fail other work properly
★ Same voltage suply
★ Resistance decrease
★ Current divide
→ Disadvantages of Series Connection
★ If one device fail other not work.
★ voltage divide
★ Resistance increase
★ Same Current suply
→ Formulas
★ I = Q / t
★ V = W / Q
★ V = IR
★ Rs = R1 + R2 + R3
★ 1/Rp = 1/ R1 + 1/R3 + 1/R3
★ H = I2Rt
★ P = VI
★ E = P t
→ Electric Bulb
★ Filament - Tungsten, because high melting point and high resistance
★ Gas - Argon / Nitrogen, they increase the life of filament
★ Working: when current passes through filament then it becomes hot and emit light.
→ Fuse
★ Safety device
★ Protect the electric circuit
★ If current is high then it become heat and melt and beak the circuit
→Heating Devices work on Joule's of heating
★ Electric Toaster
★ Electric Oven
★ Electric Kettle
★ Electric Bulb
★ Electric Fuse
- Alloys like nichrome used in electrical heating device because high melting point ang high resistance
Magnetic effects of electric current
→Magnetic field
★ Force around the magnetic
→ Properties of magnetic field
★ Never intersect
★ Closed loop
★ North pole to south - outside
★ South pole to north - inside
→Right hand thumb rule
Hold the conductor in right hand
★ Thumb - current direction
★ Four fingers - magnetic field
Direction
★ Current direction upward - magnetic field direction is anticlockwise
★ Current direction downward - magnetic field direction clockwise
→ Solenoid
★ Solenoid is the Circular coil of insulated copper wire
Magnetic field in solenoid
★ Same as bar magnet
★ Inside solenoid is uniform
Electromagnet
★ When soft iron core placed inside the Solenoid is converted into electromagnet.
Strength of magnetic field in solenoid increase
★ By increasing current.
★ By increase number of coil.
→Circular loop
Magnetic field in circular loop
★ Circles around the loop
★ Straight lines at the center:
→ Fleming's left hand rule
In Left hand
★ Thumb - motion / force
★ Fore finger - magnetic field
★ Middle finger - current
→Short circuit
★ If live wire and neutral wire direct contact cause short circuit.
Preventions
★ Use good quality wire
★ Use fuse
★ Do not connect many device to single socket
★ Do not use fault device
→Over loading
Reason for over loading
★ Sudden hike in voltage
★ connect many device to single socket
★ When live wire and neutral wire direct contact.
Prevention
★ Use good quality wire
★ Use fuse
★ Do not connect many device to single socket
★ Do not use fault device
→Earth wire
Functions
★ Providing a low resistance path
★ Leakage current send to ground
★ Preventing electric shock to the user.
→Fleming's left hand rule - activity (current carrying conductor experience force)
★ Aluminium rod place b/w poles of horse shoe magnet
★ When current is pass, rod move one one direction
★ Current is reverse, rod move another direction
Light - Reflection and Retraction
→ Reflection of light
★ Bounce back of light
→ Laws of reflection
★ Angle of incidence = angle of reflection Or i = r
★ Incident ray, reflected ray and normal, all lie on the same plane
→ Important Terms
★ Pole(P): centre of the spherical mirror.
★ Centre of curvature(C): centre of the sphere.
★ Principal focus of concave mirror (F): reflected rays actually meet at a point.
★ Principal focus of convex mirror (F): reflected rays appear to meet at a point.
★ Principal axis: line passing through C and P
★ Radius of curvature(R): distance b/w C and P
- Radius of curvature is twice of the focal length
- R = 2f
★ Focal length(f): distance b/w F and P
→Concave mirror:
Properties:
★ Reflecting surface curved inwards
★ Converging mirror
★ Real and inverted image
★ Focal length negative
Uses:
★ Torches,
★ Search light,
★ Vehicle head light,
★ Shaving mirror,
★ Dentist,
★ Solar furnaces.
→Convex mirror:
Properties:
★ Reflecting surface curved inwards
★ Diverging mirror
★ Virtual and erect image
★ Focal length positive
Uses:
★ Rear view mirror in vehicle, because it give erect and diminished image.
→Mirror formula:
★ 1/v + 1/u = 1/f
★ m= h’ / h
★ m= h’/h = -v/u
→ Refraction of light:
★ Bending of light .
★ When light travels from a rarer medium to a denser medium, it bends towards the normal.
★ When light travels from a denser medium to a rarer medium to a rarer medium, it bends away from the normal.
★ Light travels faster in a rarer medium than in a denser medium.
Laws of reflection:
i) Incident ray, refracted ray and normal, all lie on the same plane.
ii) sini/sinr = Constant.
→ Convex lens:
★ Thicker in the middle, thinner at the edge
★ Converging lens
★ Real and inverted image
★ Focal length positive.
→ Concave lens:
★ Thicker at the edge, thinner at the middle
★ Diverging lens
★ Virtual and erect image
★ Focal length negative
→ Refractive index:
★ The ratio of speed of light in air and speed of light in medium. Or n = c/v
★ The refractive index of diamond is 2·42 that means the ratio of the speed of light in air and the speed of light in diamond is 2·42.
★ Refractive index increase, speed light decreases
→Lens formula:
★ 1/v – 1/u = 1/f,
★ m = h’/h,
★ m = h’/h = v/u
★ m is positive, the image is virtual and erect
★ m is negative, the image is real and inverted.
★ m = more than 1 - large or magnified image
★ m = less than 1 - small or diminished image
★ m = 1 - image is same size of the object
→ Power of lens:
★ The power of a lens is the reciprocal of its focal length (in metres).
★ P = 1/f
★ SI unit is dioptre (D)
★ 1 dioptre is the power of a lens whose focal length is 1 metre
★ The power of a convex lens is positive (+ve)
★ The power of a concave lens is negative (-ve).
Human Eye and Colourful World
→ Human eye
★ Pupil: control the amount of light.
★ Iris: control the size of the pupil.
★ Ciliary muscle: change the eye lens focal length.
★ Retina : image formed on retina.
→Power of accommodation of eye
★ Eye can see near and far object by changing its focal length is called Power of accommodation of eye
To see near object:
★ Ciliary muscle contract.
★ Lens become thick.
★ Focal length decreases.
To see far/distant object:
★ Ciliary muscles relaxed.
★ Lens become thin.
★ Focal length increases
Near point - 25cm, Far point - Infinity
→ Myopia (Near sightedness)
Person can see near object but not see far object clearly is called myopia.
Causes:
★ Increase curvature of eye lens
★ Increase length of eye ball
Corrected by use concave lens
Hypermetropia (farsightedness)
Person can see far object but not see near object clearly is called hypermetropia.
Causes:
★ the focal length of the eye lens is too long,
★ the eyeball has become too small.
Corrected by use convex lens
Presbyopia
It occur in old age people, they not see near and far objects clearly.
Causes:
★ Weakening Ciliary muscles
★ Decreasing flexibility of eye lens
Corrected by use bifocal lens
→ Cataract
★ In old age people eye lens become Milky and cloudy,
★ Corrected by surgery
→ Dispersion of white light
★ White light split in to seven colours is called dispersion.
★ Band of colours of white light is called spectrum.
★ Least bend - Red, Most bend - Voilet
→ Formation of Rainbow
★ Water droplets act like small prism.
★ Dispersion of sun light by water droplets.
→ Twinkling of Stars
★ Due to atmospheric refraction of star light.
★ Due to continues changing refractive index.
→Planets do not twinkling
Because
★ Planets closer to the earth.
★ Extended source of light from planets.
→ Tyndall effect
★ Path of light visible due to scattering of light by particles.
→Sky appears blue
★ Atmospheric particles scatter the blue colour.
★ Blue has shorter wavelength than red.
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