# Physics Formulae To Remember

I am compiling a list of all the formulae you will need to remember for the AS Physics course

HideShow resource information
• Created by: Oskar
• Created on: 22-03-13 09:38

## Chapter 1 - Matter and Radiation

Proton: Charge = +1.6 x10(-19)c, Mass = 1.67x10(-27)

Neutron: Charge = 0c, Mass = 1.67x10(-27)

Electron: Charge = -1.6x10(-19)c, Mass = 9.11x10(-31)

Specific Charge = Charge/Mass

Power of a laser beam = nhf (n = no. of photons passing through a fixed point each second, and hf due to poton energy hf.)

Annihilation: Minimum energy of photons produced, hfmin = E0
Pair Production: Minimum energy of Photons produced = 2E0

1 Electron Volt = 1.6x10(-19)j

1 of 12

## Chapter 3 - Photoelectricity

Photon Energy, E = hf = fc/λ (with c being 3x10^8)

Maximum Kinetic Energy of an emitted electron = Ekmax - Φ

Threshold frequency, fmin = Φ/h

2 of 12

## Chapter 4 - Current and Charge

Charge, Q = It (Current x Time)

PD across a component, V = W/Q (work done / charge)

Work Done, W = QV = IVt

Electrical Power = V x I

Voltage of a component, V = IR

Resistance, R = V/I

Current, I = V/R

Resistivity, ρ = RA/L ( resistance x cross sectional area / length)

3 of 12

## Chapter 5 - Direct Current Circuits

For Parralel Resistors, I1 = V/R1, I2 = V/R2 .........

1/Rt = 1/R1 + 1/R2 + ........

Rate of heat transfer = I^2 x R = P

emf ε = E/Q = IR + Ir (r being internal resistance)

Power supplied by a cell, Iε = (I^2 x R) + (I^2 x r)

Terminal pd, V = ε - Ir

Cell Current = cell emf / total circuit resistance

Pd across series resistors = current x resistance of each resistor

current through parralel resistors = pd across both / resistor's resistance

Terminal Pd across cells in series = ε - Ir/n (n being the no. of cells)

4 of 12

## Chapter 6 - Alternating Currents

Root mean square (R.M.S) = Peak value / root 2

5 of 12

## Chapter 7 - Forces in equilibrium

For a vertical force, F = h sin ϴ (h being hypotenuse)

For a horizontal force, F = h cos ϴ

Moment of a force = F x d (d being perpendicular distance from the line of action)

For multiple forces in equilibrium, F1/sinϴ1 = F2/sinϴ2 = F3/sinϴ3

6 of 12

## Chapter 8 - On the move

For an object travelling at a constant speed V, V = s / t (s being distance and t being time)

For an object travelling round in a circle, V = 2πr / t (r being the radius of the circle)

Suvat Equations

v = u + at (doesnt need distance (s))

s = (u + v)t / 2 (doesnt need accelleration (a))

v^2 = u^2 + 2as (doesnt need time (t))

s = ut + 1/2 a t^2 (doesnt need final velocity (v))

For a speed time graph, the area under the line is the total distance travelled

7 of 12

## Motion and Force

F = ma (force = mass x accelleration)

Motion of an object - accelleration, a =(Pushing forces - draggong forces) / m

I

mpact force, F = change in kinetic energy / impact distance

8 of 12

## Chapter 10 - Work, Energy and Power

Work done = force x distance moved in the direction of the force

Work done to stretch a spring to extention, ΔL = 1/2 F Δl (Δl being change in the length)

Kinetic energy, Ek = 1/2 mv^2 (v being the speed of the object)

Work done to raise an object = force x distance moved = mg Δh

Power = ΔE / ΔT = Work done (change in energy) / time

Work done, W = Fs

Efficiency = useful energy / total energy = work done / total energy

9 of 12

## Chapter 11 - Materials

density, ρ = m / v (mass / volume)

Hookes's law - F = kΔL (k being the spring constant)

Elastic potential energy of a stretched spring , Ep = 1/2 FΔL = 1/2 KΔL^2

Young Modulus, W = stress (ρ) / strain (ε)

10 of 12

## Chapter 12 - Waves and Vibrations

Wave speed, c = fλ (frequency x wavelength)

Phase difference between to points of a wave in radians = 2πd / λ (d being the distance)

Period of a wave = 1 / f (f being the frequency)

Distance between 2 adjacent nodes = 1/2 λ

11 of 12

## Chapter 13 - Optics

Refractive index of a material = sin i / sin r (i & r being the angles of incidence and reflection)

n1 sin i = n2 sin r (n1 & n2 being the refractive indexes of the substances)

For total internal reflection, sin i = n2 / n1

Fringe separation of light in a multiple slit experiment, w = λD / s (s being fringe spacing and D being the distance between the slits and the screen)

For single slit diffraction, W = (λ / a) x 2D (W being the width of the central fringe and a being the width of the single slit)

12 of 12