IGCSE Physics formulae

Question 1

speed

Answer 1

distance travelled

time taken

Question 2

s =

Answer 2

d

t

Question 3

acceleration

Answer 3

change in velocity

time taken

Question 4

a =

Answer 4

(v-u)

t

Question 5

Hooke’s law for springs

Answer 5

Force applied to a spring is proportional to its extension, up to the limit of proportionality

Question 6

For a spring,

F =

Answer 6

kx

Question 7

Resultant force on an object

Answer 7

mass x acceleration

or

the vector sum of all the individual forces acting on it

Question 8

For an accelerating object with a resultant force on it,

F =

Answer 8

ma

Question 9

weight

Answer 9

mass x gravitational field strength

Question 10

W =

Answer 10

mg

Question 11

What is the gravitational field strength at the surface of the Earth (with units)

Answer 11

10 N/kg

(approximately)

Question 12

density

Answer 12

mass

volume

Question 13

**ρ = **

Answer 13

m

V

Question 14

moment

Answer 14

force x perpendicular distance to the line of action of the force

Question 15

moment of a force =

Answer 15

Fd

Question 16

The Principle of Moments

Answer 16

If a body is in equilibrium,

sum of clockwise moments = sum of anticlockise moments

F₁d₁ + F₂d₂….= F₃d₃ + F₄d₄…

Question 17

current (in amps)

Answer 17

charge (in coulombs)

time (in seconds)

Question 18

Q =

Answer 18

It

Question 19

I =

Answer 19

Q

t

Question 20

Refractive index of a material

Answer 20

speed of light in a vacuum

speed of light in the material

Question 21

n =

Answer 21

sin i

sin r

Question 22

Electromagnetic spectrum in order of decreasing wavelength

Answer 22

Question 23

frequency (in Hz)

Answer 23

number of waves passing per second

Question 24

f =

Answer 24

1

T

(T= the period of the, i.e. the time for one complete wave)

Question 25

wave speed (in m/s)

Answer 25

frequency (in Hz) x wavelength (in m)

Question 26

For a wave **v =**

Answer 26

**fλ**

Question 27

The prefix **M** in front of a unit means?

Answer 27

"mega" / million e.g. **1Mz = 1,000,000 Hz**

Question 28

**E_GPE =**

Answer 28

**mgΔh**

Question 29

**E_KE = **

Answer 29

**_mv²_** **2**

Question 30

Efficiency

Answer 30

_useful energy_ ( x 100%) total energy supplied

Question 31

Work done against a force

Answer 31

force x distance moved against the force

Question 32

**W =**

Answer 32

**Fd**

Question 33

Power

Answer 33

_energy transferred_ time taken

Question 34

**P**

Answer 34

**_E_** **t**

Question 35

**E =** (in terms of power)

Answer 35

**Pt**

Question 36

Pressure

Answer 36

_force_ area the force is applied over

Question 37

**p =**

Answer 37

**_F_** **A**

Question 38

The SI units of pressure are?

Answer 38

pascal _or_ newtons per square metre **Pa N/m²** 

Question 39

**p =** (due a liquid of depth of **h**)

Answer 39

**hρg**

Question 40

Boyle's Law for a fixed mass of gas at a constant temperature in locations **₁** and **₂**

Answer 40

**p₁V₁ = p₂V₂**

Question 41

Energy required to change state **E =**

Answer 41

**mL**

Question 42

Energy required to raise the temeprature of an object **E =**

Answer 42

**mc(θ₁-θ₂)** _or_ **mcΔT**

Question 43

Units of specific heat capacity

Answer 43

**J/(kg ****°C****)**

Question 44

Electrical energy transferred **E =**

Answer 44

**QV**

Question 45

Resistance of a component in an electric circuit

Answer 45

_Potential Difference across the component_ current through the component

Question 46

**V =**

Answer 46

**IR**

Question 47

Electrical power **P =**

Answer 47

**IV**

Question 48

Energy transferred by an electric current **E =**

Answer 48

**ItV**

Question 49

The transformer equation

Answer 49

**_V__p = _N__p** **V_s N_s**

Question 50

Assuming a transformer is 100% efficient, the power on either side is linked by the equation

Answer 50

**V_pI_p = V_sI_s**

Question 51

For resistors in series, **R_{total =}**

Answer 51

**R₁ + R₂ + ...**

Question 52

For resistors in parallel, **_1_ = ** **R_total**

Answer 52

**_1_ + _1_ + ...** **R₁ R_{2          .}**

Question 53

The total Potential Difference across components in series the same branch of an electric circuit

Answer 53

**= V1 + V2 + ...**

Question 54

The sum of the currents flowing into a junction in an electric circuit

Answer 54

= the sum of all the currents flowing out of the junction