physics

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A 5.0-cm real object is placed at a distance of 30.0 cm from a concave mirror of focal length 10.0 cm. Find the location of the image.
A. 6 cm
B. 10 cm
C. 15 cm
D. 60 cm

Is it B. 10 cm?

Which of the following objects can set fire to a piece of paper in the presence of sunlight?
A. Double concave lens
B. Convex lens
C. Convex mirror
D. Concave lens

Is it B?

• physics - ,

right on the second. On the first, how can the image be at the focus? That is where infinite distance rays converge.

• physics - ,

Oh yeah. I re-did it and the answer is C-15cm...?

• physics - ,

A 5.0-cm real object is placed at a distance of 30.0 cm from a concave mirror of focal length 10.0 cm.
Find the location of the image.

Height of the object = 5.0 cm
Distance = 30.0 cm
Focal length = 10.0 cm

This is the equation:
1/Do + 1/v = 1/f

which means:
1/[distance] + 1/[location] = 1/[Focal length]

1/30.0 + 1/v = 1/10.0
1/ ((1/10.0) - (1/30.0)) = v
14.999999 = v = the location

Which of the following objects can set fire to a piece of paper in the presence of sunlight?