What is the magnification of a 4 cm tall object placed 40 cm from a concave mirror having a focal length of 10 cm?



0.33

-0.33

1.33

-1.33

I'm thinking B.

-0.33

To calculate the magnification of an object placed in front of a mirror, you can use the formula:

Magnification (m) = - (image distance / object distance)

Where:
- Image distance is the distance of the image formed by the mirror from the mirror itself.
- Object distance is the distance between the object and the mirror.

In this case, the object distance is given as 40 cm and the focal length of the concave mirror is 10 cm.

Now, to find the image distance, you can use the mirror equation:

1 / focal length = 1 / object distance + 1 / image distance

Plugging in the values, we can rearrange the equation to solve for the image distance:

1 / 10 = 1 / 40 + 1 / image distance

Simplifying the equation further:

1 / image distance = 1 / 10 - 1 / 40

1 / image distance = (4 - 1) / 40

1 / image distance = 3 / 40

image distance = 40 / 3 cm

By substituting the image distance (40 / 3 cm) and the object distance (40 cm) into the magnification formula, we can calculate the magnification:

magnification = - (image distance / object distance)
magnification = - (40/3) / 40
magnification = - (4/3)

Therefore, the correct answer is -1.33 (option D).