# Physics Formulas For ICSE Class 10 Chapter Wise

Students should refer to ICSE class 10 physics formulas given here prepared as per the chapters given in Selina physics class 10 book which has been recommended for class 10 students. You can also refer to ICSE class 10 physics solutions which have been provided on our website. These formulas for Physics in Standard 10th ICSE are very important as it will help you to solve many difficult questions which can come in your exams

#### Physics Formulas For ICSE Class 10 Chapter Force

1. Moment of force = Force × Perpendicular distance of force.
SI unit = Newton × metre ( Nm )
CGS unit = dyne × cm
Important conversion :
1 Nm = 10⁵ dyne × 10² cm = 10⁷ dyne cm
2. Moment of Couple = Either force × perpendicular distance between the two forces.
3. Principle of moments = Sum of anticlockwise moments = Sum of clockwise moments.

Center of Gravity

1. Rod = Mid point of Rod.
2. Circular Disc = Geometric centre.
3. Solid or hollow = Geometric center of sphere.
sphere.
4. Solid or Hollow = Mid point of Axis of Cylinder.
Cylinder
5. Solid cone = At a height h/4 from the base, on its axis.
6. Hollow Cone = At a height h/3 from the base.
7. Circular ring = Centre of Ring.
8. Triangular Lamina = The point of intersection of medians.
9. Parallelogram or rectangular lamina or square or rhombus = The point of intersection of diagonals.

#### Physics Formulas For ICSE Class 10 Chapter Work Energy and Power

1. Work = Force × displacement
W = F × S it is a scalar quantity.
W for an inclination = F × S costhita
SI unit = Joule i.e. Newton × metre
CGS unit = Erg i.e. dyne × cm.

Important conversion :
1 joule = 10⁵ dyne × 10² cm = 10⁷ dyne cm = 10⁷ erg

SPECIAL CASES :
1. If the displacement is in direction with the force then work done is positive.
2. If the displacement is normal to the direction of force then work done is zero.
3. If displacement is in direction opposite to the force then work done is negative.

power

Power = Work / Time .
It is a scalar quantity.
For a constant force with change in displacement Power = Force × average speed.
P = F × v.
SI unit = Watt = Joule/second.
CGS unit = erg/s
Bigger units of Power :
1. Kilowatt (kw) = 10³ W
2. Megawatt (MW) = 10⁶ W
3. Gigawatt ( GW ) = 10⁹ W
Smaller units =
milliwatt = 10^-3 W , microwatt = 10^-6 W.
Horse Power : 1 HP = 746W = 0.746 kW.

Energy

The energy of a body is its capacity to do work.
SI unit = Joule
CGS unit = erg

Bigger units of Energy :
1. Watt hour ( Wh) = 3600 J = 3.6 kJ
2. Kilowatt hour (kwh) = 3.6 × 10⁶ J = 3.6 MJ
3. Calorie : 1 calorie = 4.18 J
4. Electron volt ( eV ) = 1 eV = 1.6 × 10^-19 J.
Force due to gravity = mg
at a certain height = mgh
Gravitational potential energy U = mgh
Kinetic energy = 1/2 mass × (velocity)²
= 1/2 mv²

Work-Energy Theorem

Let u = initial velocity
v = final velocity.
W = 1/2 mv² – 1/2 mu².
Thus work done on a body is equal to increase in Kinetic energy.

#### Physics Formulas For ICSE Class 10 Chapter Machine

1. Mechanical advantage ( M.A. ) = Load ( L ) ÷ Effort (E)
2. Velocity Ratio = Velocity of Effort ÷ Velocity of load
V.R. = dE / dL.
3. Work input = work done by effort.
4. Work output = work done on load.
5. Efficiency = work output/ work input

For an ideal machine
output energy = input energy.

Relation between above formulas : M.A. = V.R. × Efficiency .
All the above formulas are unit less.

Pulley

SINGLE FIXED PULLEY
M.A. = 1
V.R. = 1
Efficiency = 1 or 100%

SINGLE MOVABLE PULLEY
M.A. = 2
V.R. = 2
Efficiency = 1 or 100%

FOR COMBINATION OF PULLEYS
M.A. = 2^n
V.R. = 2^n
Efficiency = 1 or 100%.

Block and Tackle System

1. Effort required to balance the load
E = L/n , n = number of pulleys, L = load.
In this system the effort gets multiplied n times therefore it acts as a force multiplier.
Work done by effort = effort × distance moved
= E × nd = nEd.
= L × d
= nE × d = nEd.
For greater efficiency the pulleys in the lower block should be as light as possible.

#### Physics Formulas For ICSE Class 10 Chapter Refraction of Light at Plane Surfaces

For normal incidence angle of incidence is zero degree.
Refractive index ( ų ) = sin i / sin r
Or
Speed of light in vaccum or air ÷ speed of light in that medium.

The refractive index of transparent surfaces is always greater than 1.

Principle of reversibility :

Lateral Displacement :

Important formula :

Angle of Deviation :

REAL AND APPARENT DEPTH :

SHIFT :

CRITICAL ANGLE :

#### Physics Formulas For ICSE Class 10 Chapter Refraction Through A Lens

LENS FORMULA :

LINEAR MAGNIFICATION :

Q1: A: at what position a candle of length 3 cm be placed in front of a convex lens so that its image of length 6cm be obtained on a screen placed at a distance of 30cm behind the lens?

Q2: A lens forms the image of an object placed at distance 15 cm from it at a distance 60 cm in front.
find
1:the total the focal length
2: the magnification and
3: the nature of the first image.

Q3: An object is placed at a distance of 20 cm in front of a concave lens of focal length 20cm. find
1: the position of image and
2: the magnification of the image

Q4: A convex lens forms an inverted image of size same as that of the object which is placed at a distance 60 cm in front of the lens. Find
1 : the position of image
2 : the focal length of the lens.

Q5: The power of the lens is + 2.0 D. Find its focal length and state the kind of lens.

Q6: The power of a lens is -2.0 D. Find its focal length and its kind. IMP

#### Physics Formulas For ICSE Class 10 Chapter Spectrum

Relation between speed, frequency and wavelength of electromagnetic waves :
C = f λ

numerical

• Calculate the frequency of yellow light of wavelength 550 nm. the speed of light is 3×10^8 ms^-1.
• An Electromagnetic wave has a frequency of 500MHz and a wavelength of 60cm.
a) calculate the speed of the wave.
b) name the medium through which it is travelling.

#### Physics Formulas For ICSE Class 10 Chapter Sound

Relationship between wave velocity V,frequency f,wavelength
V=fλ
2.Relationship between time period t and it’s frequency f of a wave : f=1/T
3.Speed of longitudnal waves in a gaseous medium of density d at a pressure P is :

4.Speed of trasverse waves in a streched string with tension t is given as :

ECHO:

Time taken to hear the echo: t=2d/V or d=Vt/2
2.To determine the speed of the sound by echo method: V=2d/t

LOUDNESS & INTENSITY:

Relationship between Loudness and intensity: L=K log I10

#### Physics Formulas For ICSE Class 10 Chapter Current Electricity

CHARGE : Units of Charge:
The S.I unit of charge is coulumb denoted by symbol (C).
The smaller units of Charge are :
Milli-coulomb
• Micro-coulomb
Nano-coulomb
1mC=10-³ C , 1 uC=10-⁶ C and 1nC=10-⁹ C

CURRENT : Units of current:
S.I unit of current is Ampere denoted by symbol (A)
The smaller units of Ampere:
• Milli-ampere (mA)
• Micro-ampere (uA)
1mA = 10-³A and 1uA = 10-⁶A

Current ( I ) = Q / t
Q = n × e
I = ne / t

• POTENTIAL DIFFERENCE :
V = W / Q
Unit of potential difference
S.I unit of potential difference is volt denoted by symbol (V).
It is a scalar quantity.
1volt = 1joule/1coulumb.

• RESISTANCE :
Unit of Resistance
S.I unit of resistance is Ohm.
Unit of R = Unit of V/Unit of I.
Higher resistance are measured in:
1 kilo-ohm = 10-³ ohm
1 Mega-ohm = 10⁶ ohm

Resistance is directly proportional to :
Lenght if conductor and temperature of the conductor.
Indirectly proportional to thickness of conductor.

• OHM’S LAW
Formula for Ohm’s law: V=IR
Where ,
V is potential difference.
I is current.
R is resistance.
• Conductance =
Formula : Conductance = 1/Resistance.
Unit = ( ohm ) ^-1

• SPECIFIC RESISTANCE = Ra / l
R = resistance, a = area of cross section, l = lenght.
Unit = ohm × metre

Conductivity = 1 / specific resistance.
Unit = 1 / ohm × metre.

ELECTROMOTIVE FORCE :
Formula : E = W/q
Where, E is e.m.f, W is work done q is Charge.

TERMINAL VOLTAGE :
Formula : V = w’/q
Where, V is potential difference . W’ is work done, q is charge.

VOLTAGE DROP IN A CELL :
Formula : v = w/q
Relationship between e.m.f & terminal voltage of a cell :
Formula : E=V+v Or V=E-v
Internal resistance of a cell Formula : v=Ir.

MOST IMPORTANT FORMULAS
1: Total resistance of circuit = R+r
2: Current drawn from the cell : I = E/R+r.
3: E.m.f of a cell: (Use this one not the above one) E = I(R+r)
4:The terminal voltage of the cell: V=IR.
5: Voltage drop due to internal resistance = v=Ir
6: Internal Resistance:
i)r=v/I
ii)E-V/I
iii)E-V/V/R
iv)(E/V-1)R.

SERIES & PARALLEL COMBINATION :

1:Equivalent resistance in series: Rs = R1 + R2 + R3 …….+ Rn times..
2:Equivalent resistance in parallel: 1/Rp = 1/R1 + 1/R2 + 1/R3 ……+1/Rn

#### Physics Formulas For ICSE Class 10 Chapter Calorimetry

HEAT : Units of heat :
S.I unit of heat is joule (J)
And the other unit commonly ised unit is calorie (cal).
Relationship between calorie and heat: 1calorie = 4.186J or 4.2 J nearly.

TEMPERATURE: Unit of temperature:
S.I unit of temperature is Kelvin (K)
The other commonly used unit is degree celsius (C).
Relationship between celsius and kelvin: TK = 273 + tC.
Amount of heat absorbed:
Formula : Q=mc×delta t.

HEAT CAPACITY : Unit of heat capacity:
S.I unit of heat capacity is Joule per kelvin (JK-¹).

It is denoted by (C’).
Formula for heat capacity:
C’=Q/ delta t

Where ,
C’ is heat capacity
Q is total heat energy
Delta t is temperature difference

SPECIFIC HEAT CAPACITY : Unit of heat capacity:
S.I unit of heat capacity is Joule per kilogram kelvin (JK-¹).

It is denoted by (c).
Formula for specific heat capacity:
c = Q/m× delta t

RELATIONSHIP BETWEEN HEAT CAPACITY AND SPECIFIC HEAT CAPACITY : Heat capacity C’ = mass m × specific heat capacity c

Principal of caloriemeter: Heat energy lost by the hot body = Heat energy gained by cold body.

Formula : m1 c1 (t1 -t) = m2 c2 (t -t2)

Where, M is mass, c is specific heat capacity t is temperature.

LATENT HEAR AND SPECIFIC LATENT HEAT :

Unit of specific Latent heat :
S.I unit of specific latent heat is Joule per kilogram (Jkg-¹).
It is denoted by (L)

Formula: L = Q/m or Q= mL
Where,
L is specific heat capacity
Q is total heat absorbed
m is mass.

ALPHA EMISSION :

BETA EMISSION :

GAMMA EMISSION :

IMPORTANT TERMS

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