Physics Formulae

FORCES AND MOTION 1.

=

Average speed v

=

 s

 s

t 

2. Acce Accele lera rati tion on,, a

3. a. c.

v

 s

=

Total distance travelled

=

=

= ut  +

2

 b.  s d.

Momentu tum

5. a.  b. 6. a.

=

u

+

v

 F  =

=

u + v    t  2  

=

v

2

=

mv

−

=

mv

−

 F 

24. 24. a. Refr Refrac acti tive ve inde index, x, n

=

 b.  b. Refr Refract activ ivee index index,, n

=

c. Refr Refract activ ivee ind index ex,, n

=

 pA b. Force,  F  =  pA =

=

 F 1

17. Pascal's principle:

mu

hρ   g 

Vg   ρ 

 A1

n

=

=

26. Lens formula: formula:

HEAT  F  m a

Weight of  object, W 

=

W  m g 

mg 

  b. Gravitati Gravitational onal field strength, strength,  g  =

W  m

W   F s

8. Work Work done done,, W  =  Fs W 

W   P t 

t 

1 2

mv

 b.  b. Pote Potent ntia iall ener energy gy = mgh 11. a. Hook ooke's e's law law::  F  = kx

20. Latent Latent heat, Q

=

Boyle's law

 p1 : T 1

  b. b. Pres Pressu sure re law law

1 1  Fx  Fx = kx 2  b. Elasti Elasticc poten potenti tial al energ energy y= 2 2

c.

Charles' law

K  =θ 

:  p1V 1

2

 F  k x

Real depth Apparent depth

1   f  

=

1

1 u

+

1 v

27. Linear Linear magnification magnification,, m =

Height of  object Height of  image

28. Astronomi Astronomical cal telescope

mc θ 

a. Magnif Magnifyin ying g power power of teles telescop cope, e, M  =

ml 

21. Absolute Absolute temperatur temperature, e, T  22. a.

=

sin sin c

  f  

θ 

19. Heat absorbed absorbed or heat released, released, Q

sin sin r  1

Speed of  light in medium

 A2

   X  −  X ais   o   18. Temperature, θ  =   ×100 C −  X   X  ais     stim

sin i

Speed of  light in vacuum

 P  = 25. Power of a lens, lens, P 

 F 2

r  2

d. Refr Refract activ ivee inde index, x,

ρ Vg 

mu

t 

10. 10. a. Kine Kineti ticc ene energ rgy y=

 ρ 

mg 

mv

 Ft   Ft 

 F   p A

Buoyant force = weight of liquid displaced =

mv − mu

9. Power,  P  =

Press ur ure,  p

 ρ V  m

15. Archimede Archimedes' s' Principle Principle

= u 2 + 2as

 b.  b. Resu Result ltan antt force force,,  F  = ma 7. a.

ρ V  =

23. Focal length of curved mirror, mirror,   f   =

m

V 

16. Law of flotation flotation Weight of object = Buoyant force

Change of  momentum Impulse

=

LIGHT

m

 A 14. Pressure Pressure in a liquid liquid,,  p

=      2

Density , ρ  =

c. Volume , V  13. a.

t 

at 2

12. a.

b. Mass, m  s v t 

v −u

e. Aver Averag agee spe speed ed = 4.

Time taken  s t  = v

vt 

u + at 

1

FORCES AND PRESSURE

:

V 1 T 1

= =

=

o

C + 273

 p 2V 2

 p 2 T 2

 b. Distan Distance ce betwe between en lens lenses es =   f  o

+

  f  o   f  e

f  e

WAVES 29. 29. Frequ Frequenc ency, y,   f   = 30. 30. Wave Wave speed, speed, v

=

1

T    f  λ 

V 2 T 2

31. Young's double slit experiment experiment λ   D Separation of fringes,  x = a

ELECTRICITY 32

Ch

Q

 It 

λ 

=

ax  D

=

v u

 b. Current,  I  =

Q

c.

t 

33. Potential difference or voltage, V  34. Energy transferred, W  35. a. Resistance,  R

=

=

=

W  Q

QV 

Curre nt,  I  =

 R

 R1

=

W  Q V 

 b.  E  =  I ( R + r )

V   I R

a.

V S V P

=

 N S

 b.

 N P

c. Efficiency =

c. p.d. across a resistor 

∝

 R

Efficiency =

 R

=

1  R1

+

1  R2

+

 I PV P

×100

 I PV P

=

100 %

×

%

1

a. Power transmitted,  P  =  IV 

 R3

 b. Power dissipated,  P  =  I 2 R

38. a.

c.

=

Energy, W  =

1

RADIOACTIVITY

 R

44. Einstein's equation :  E  = mc 2

2

 I   Rt  V 

2

 R

W 

39. a.

Power,  P  =

40. a.

Power,  P  =  IV 

t 

b. Power,  P  =  I 2 R

t 

W   P t 

F  Ft  W  W  E  P 

 N  N s  N J J J s –1 ,W

Density Volume

ρ  V 

kg m –3 m3

Extension of spring

x, e

Physical Quantity Speed / Velocity Distance / Displacement Time

Symbol  Unit v s, d  t 

 –1

ms m s

cm, m

k 

 N cm –1 , N m –1

Pressure

P 

Pa

Area

A

m2

Temperature in celsius Heat

θ  Q

Specific heat capacity Specific latent heat

c l 

J kg –1 oC –1 J kg –1

Absolute temperature Focal length Radius of curvature Angle of incidence

T  f  r  i

K  mm, cm, m mm, cm, m

Angle of refraction

r  n c P  u v T  f  λ  Q I  V  R W  P  E  r 

Charge of an electron Speed of light

 b. Energy, W  =  Pt   P   I V 

Force Impulse Weight Work done Energy Power 

Power of a lens Object distance Image distance Period Frequency Wavelength Electric charge Current Potential difference Resistance Electrical energy Electrical power  Electromotive force (emf) Internal resistance Peak voltage

Energy, W  =  IVt 

 b. Energy, W 

kg m s –1 , N s

Critical angle

 b. same p.d. across the resistors c. current in a resistor  ∝

p

Refractive index

43. Transmission of electricity

37. Resistors in PARALLEL: 1

 I SV S

Input  power 

 I SV S

r 

Momentum

Force constant

Output  power 

 b. same current flows in each resistor 

a.

 I

42. Transformer 

R3

+

 E-V 

EMF,  E  = V  +  Ir 

ELECTROMAGNETISM

=  IR

 R

 R2

a.

 I 

V 

+

 R

41. For battery with internal resistance:

36. Resistors in SERIES: a.

V  2

V 

 b. Potential difference or voltage, V  c.

Power,  P  =

o

C J

degree ( o ) degree ( o )  –  degree ( o ) dioptre (D) cm, m cm, m s Hz cm, m C A V Ω

J W V Ω

V o

V

e

C

c

m s –1

SPM Physics