Y1 Formulas

Question 1

Density / Mass / Volume

Answer 1

ρ=m/V (Density = mass/Volume)

Question 2

Weight / Mass / Gravitational field strength

Answer 2

W=mg (Weight = mass x gravitational field strength)

Question 3

Wave speed / Frequency OR Time / Wavelength

Answer 3

v=fλ or v=λ/T (speed = frequency x wavelength or speed = wavelength/Time)

Question 4

Frequency / Time

Answer 4

f=1/T (frequency = 1/Time)

Question 5

Refractive index / θi / θr
(When light is entering from air/vacuum)

Answer 5

n=sin i/sin r (refractive index = sin angle of incidence/sin angle of refraction)

Question 6

Refractive index / θi / θr
(When light is not entering from air/vacuum)

Also known as Snell’s law

Answer 6

n1 sin θ1=n2 sin θ2 (refractive index of first material sin angle of incidence = refractive index of second material sin angle of refraction)

Numbers must be written as subscripts

Question 7

Refractive index (does not involve θi or θr)

Answer 7

n=real depth/apparent depth(refractive index = …)
OR
n=c/v (refractive index = speed of light in vacuum/speed of light in given medium)

Second formula only works when light is entering the medium from air or a vacuum

Question 8

Refractive index / θc (When light is entering from air/vacuum)

Answer 8

n=1/sin c (refractive index = 1/sin critical angle)

Question 9

Refractive index / θc (When light is not entering from air/vacuum)

Answer 9

n1 sin θc=n2 (refractive index of first material sin critical angle = refractive index of second material)

Numbers and “c” must be written as subscripts

Question 10

Focal length / Object distance / Image distance

Also known as the Thin Lens Equation

Answer 10

1/xo+1/xi=1/f (1/object distance + 1/image distance = 1/focal length)

“o” and “i” must be written as subscripts

Question 11

Magnification / Object height / Image Height

Answer 11

m=hi/ho (magnification = image height/object height)

“o” and “i” must be written as subscripts

Question 12

Magnification / Object distance / Image distance

Answer 12

m=-xi/xo (magnification = negative image height/object height)