A concave lens has focal length

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Geometric Optics · Geometric Optics

Problem

20\,\text{cm}

. An object is placed

30\,\text{cm}

in front of the lens along the principal axis. Which of the following sign combinations for

(u,\,v,\,f)

follows the Cartesian sign convention? (a)

(+30\,\text{cm}, -12\,\text{cm}, -20\,\text{cm})

(b)

(-30\,\text{cm}, -12\,\text{cm}, +20\,\text{cm})

(c)

(-30\,\text{cm}, -12\,\text{cm}, -20\,\text{cm})

(d)

(-30\,\text{cm}, +12\,\text{cm}, -20\,\text{cm})