IGCSE Physics Equations
Welcome to the IGCSE Physics Equations page, your go-to resource for all the essential equations required for the 0625 syllabus. Here, you’ll find a comprehensive list of equations organized by topic, making it easier for you to reference and revise. Whether you’re preparing for exams or doing last-minute revisions, this page ensures that all the critical formulas are at your fingertips, helping you solve problems efficiently and confidently.
1. Motion, Forces, and Energy
1. Average Speed
\( v = \frac{d}{t} \)
\( v = \) velocity or speed (ms-1)
\( d = \) distance (m)
\( t = \) time (s)
2. Average Velocity
\( v = \frac{s}{t} \)
\( v = \) velocity (ms-1)
\( s = \) displacement (m)
\( t = \) time (s)
3. Acceleration
\( a = \frac{v - u}{t} \)
\( a = \) acceleration (ms-2)
\( v = \) final velocity (ms-1)
\( u = \) initial velocity (ms-1)
\( t = \) time (s)
4. Weight
\( W = mg \)
\( W = \) weight (N)
\( m = \) mass (kg)
\( g = \) gravitational field strength (ms-2)
5. Force
\( F = ma \)
\( F = \) force (N)
\( m = \) mass (kg)
\( a = \) acceleration (ms-2)
6. Density
\( \rho = \frac{m}{V} \)
\( \rho = \) density (kgm-3)
\( m = \) mass (kg)
\( V = \) volume (m3)
7. Hooke's Law
\( F = kx \)
\( F = \) force (N)
\( k = \) spring constant (Nm-1)
\( x = \) extension (m)
8. Pressure
\( P = \frac{F}{A} \)
\( P = \) pressure (Pa)
\( F = \) force (N)
\( A = \) area (m2)
9. Fluid Pressure
\( P = \rho gh \)
\( P = \) pressure (Pa)
\( \rho = \) density (kgm-3)
\( g = \) gravitational field strength (ms-2)
\( h = \) height (m)
10. Work
\( W = Fd \)
\( W = \) work (J)
\( F = \) force (N)
\( d = \) distance moved (m)
11. Power
\( P = \frac{W}{t} \)
\( P = \) power (W)
\( W = \) work (J)
\( t = \) time (s)
12. Kinetic Energy
\( KE = \frac{1}{2}mv^2 \)
\( KE = \) kinetic energy (J)
\( m = \) mass (kg)
\( v = \) velocity (ms-1)
13. Gravitational Potential Energy
\( GPE = mgh \)
\( GPE = \) gravitational potential energy (J)
\( m = \) mass (kg)
\( g = \) gravitational field strength (ms-2)
\( h = \) height (m)
14. Efficiency
\( \text{Efficiency} = \frac{P_{\text{out}}}{P_{\text{in}}} \times 100\% \)
\( P_{\text{out}} = \) useful power output (W)
\( P_{\text{in}} = \) total power input (W)
15. Moment
\( M = Fd \)
\( M = \) moment (Nm)
\( F = \) force (N)
\( d = \) perpendicular distance from pivot (m)
16. Sum of Moments
\( \sum M_{\text{clockwise}} = \sum M_{\text{anticlockwise}} \)
\( M = \) moment (Nm)
17. Momentum
\( p = mv \)
\( p = \) momentum (kgms-1)
\( m = \) mass (kg)
\( v = \) velocity (ms-1)
18. Impulsive Force
\( F = \frac{\Delta p}{t} \)
\( F = \) impulsive force (N)
\( \Delta p = \) change in momentum (kgms-1)
\( t = \) time (s)
19. Impulse
\( \Delta p = mv - mu \)
\( \Delta p = \) change in momentum (kgms-1)
\( m = \) mass (kg)
\( v = \) final velocity (ms-1)
\( u = \) initial velocity (ms-1)
2. Thermal Physics
1. Boyle's Law
\( P_1V_1 = P_2V_2 \)
\( P_1 = \) initial pressure (Pa)
\( V_1 = \) initial volume (m3)
\( P_2 = \) final pressure (Pa)
\( V_2 = \) final volume (m3)
2. Energy (Specific Heat Capacity)
\( Q = mc\Delta\theta \)
\( Q = \) energy (J)
\( m = \) mass (kg)
\( c = \) specific heat capacity (Jkg-1°C-1)
\( \Delta\theta = \) temperature change (°C)
3. Celsius to Kelvin Conversion
\( T(K) = T(°C) + 273.15 \)
\( T(K) = \) temperature in Kelvin (K)
\( T(°C) = \) temperature in Celsius (°C)
3. Waves
1. Wave Speed
\( v = f\lambda \)
\( v = \) wave speed (ms-1)
\( f = \) frequency (Hz)
\( \lambda = \) wavelength (m)
2. Frequency
\( f = \frac{1}{T} \)
\( f = \) frequency (Hz)
\( T = \) period (s)
3. Refractive Index
\( n = \frac{\sin i}{\sin r} \)
\( n = \) refractive index
\( i = \) angle of incidence
\( r = \) angle of refraction
4. Refractive Index (Speed of Light)
\( n = \frac{c}{v} \)
\( n = \) refractive index
\( c = \) speed of light in vacuum (ms-1)
\( v = \) speed of light in material (ms-1)
5. Critical Angle
\( n = \frac{1}{\sin c} \)
\( n = \) refractive index
\( c = \) critical angle
4. Electricity and Magnetism
1. Current
\( I = \frac{Q}{t} \)
\( I = \) current (A)
\( Q = \) charge (C)
\( t = \) time (s)
2. Voltage
\( V = \frac{W}{Q} \)
\( V = \) voltage (V)
\( W = \) energy transferred (J)
\( Q = \) charge (C)
3. Ohm's Law
\( V = IR \)
\( V = \) voltage (V)
\( I = \) current (A)
\( R = \) resistance (Ω)
4. Power (Current and Voltage)
\( P = IV \)
\( P = \) power (W)
\( I = \) current (A)
\( V = \) voltage (V)
5. Power (Current and Resistance)
\( P = I^2R \)
\( P = \) power (W)
\( I = \) current (A)
\( R = \) resistance (Ω)
6. Energy Transferred
\( W = IVt \)
\( W = \) energy transferred (J)
\( I = \) current (A)
\( V = \) voltage (V)
\( t = \) time (s)
7. Energy Transferred (Power)
\( W = Pt \)
\( W = \) energy transferred (J)
\( P = \) power (W)
\( t = \) time (s)
8. Resistors in Series
\( R_{\text{total}} = R_1 + R_2 + R_3 + \dots + R_n \)
\( R_{\text{total}} = \) total resistance (Ω)
\( R_1, R_2, \dots, R_n = \) individual resistances (Ω)
9. Resistors in Parallel
\( \frac{1}{R_{\text{total}}} = \frac{1}{R_1} + \frac{1}{R_2} + \dots + \frac{1}{R_n} \)
\( R_{\text{total}} = \) total resistance (Ω)
\( R_1, R_2, \dots, R_n = \) individual resistances (Ω)
10. Resistance
\( R = \frac{\rho l}{A} \)
\( R = \) resistance (Ω)
\( \rho = \) resistivity (Ωm)
\( l = \) length (m)
\( A = \) cross-sectional area (m2)
11. Transformers (Voltage)
\( \frac{V_s}{V_p} = \frac{N_s}{N_p} \)
\( V_s = \) voltage in secondary coil (V)
\( V_p = \) voltage in primary coil (V)
\( N_s = \) turns in secondary coil
\( N_p = \) turns in primary coil
12. Transformers (Current)
\( \frac{V_s}{V_p} = \frac{I_p}{I_s} \)
\( V_s = \) voltage in secondary coil (V)
\( V_p = \) voltage in primary coil (V)
\( I_s = \) current in secondary coil (A)
\( I_p = \) current in primary coil (A)
5. Nuclear Physics
1. Alpha Decay
\( ^A_ZX \rightarrow ^{A-4}_{Z-2}Y + ^4_2He \)
\( ^A_ZX = \) parent nucleus
\( ^{A-4}_{Z-2}Y = \) daughter nucleus
\( ^4_2He = \) alpha particle
2. Beta Decay
\( ^A_ZX \rightarrow ^A_{Z+1}Y + ^0_{-1}e \)
\( ^A_ZX = \) parent nucleus
\( ^A_{Z+1}Y = \) daughter nucleus
\( ^0_{-1}e = \) beta particle (electron)
3. Gamma Decay
\( ^A_ZX \rightarrow ^A_ZX + \gamma \)
\( ^A_ZX = \) nucleus
\( \gamma = \) gamma ray
6. Space Physics
1. Average Orbital Speed
\( v = \frac{2\pi r}{T} \)
\( v = \) average orbital speed (ms-1)
\( r = \) average radius of the orbit (m)
\( T = \) orbital period (s)
2. Hubble's Law
\( v = H_0 d \)
\( v = \) speed away from us (ms-1)
\( H_0 = \) Hubble constant (s-1)
\( d = \) distance of a far galaxy (m)
3. Hubble's Law (Alternative Form)
\( \frac{d}{v} = \frac{1}{H_0} \)
\( d = \) distance of a far galaxy (m)
\( v = \) speed away from us (ms-1)
\( H_0 = \) Hubble constant (s-1)
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