An object of height is placed in front of a concave mirror

PHYSICS · Single correct · A Level · Physics · Measurements and their errors · Measurements and their errors

Problem

An object of height

(5.00 \pm 0.05)\,\text{cm}

is placed

(28.0 \pm 0.2)\,\text{cm}

in front of a concave mirror. The virtual image is measured to have a height of

(9.00 \pm 0.10)\,\text{cm}

. Which of the following best represents the focal length of the mirror with its absolute uncertainty? (a)

f = (18 \pm 2)\,\text{cm}

(b)

f = (63 \pm 2)\,\text{cm}

(c)

f = (31 \pm 2)\,\text{cm}

(d)

f = (63 \pm 6)\,\text{cm}