Question

For a situation of a certain concave mirror creating an image of an object, when p=6cm, q=12cm. What is the value of p when q=-12cm?

Group of answer choices

• -6cm.

• -3cm.

• 3cm.

• 6cm.

• 15cm.

Answer 1

for concave mirror, focal length, f is positive

so,

1/f = 1/p + 1/q

1/f = 1/6 + 1/12

f = 4 cm

Now,

q = -12 cm

then

1/p = 1/f - 1/q

1/p = 1/4 + 1/12

p = 3 cm