An obect is placed 20cm from a convex mirror of focal length 12cm. where does the image form?

7.5 cm behind the mirror

Explanation:

Applying,

Using the real is positive convection: All real distance from the mirror are positive

1/f = 1/v+1/u Equation 1

Where f = focal length of the mirror, v = image distance, u = object distance

From the question,

f = -12 cm, u = 20 cm

substitute these value into equation 1

1/(-12) = (1/20)+1/v

(-1/12)-(1/20) = 1/v

1/v = (-5-3)/60

1/v = -8/60

v = -60/8

v = -7.5 cm

Hence the image is formed 7.5 cm behind the mirror.

Both flashlight and laser emit light. The difference is that the flashlight emits light by spontaneous emission and there are many light waves with different frequencies and has no preferential way of travel. The light waves in the laser beam on the other hand are at the same frequency and all waves have the same direction. According to this, the following statement is correct: The light from the flashlight lights up a larger area of the paper.