Question

1. An object is placed 1.65 cm in front of a mirror. An image is formed 6 cm in front of the mirror. Find the focal length of the mirror.

2. A 2.1 m tall object is placed 8.5 m from a truck mirror. If an image is formed -1.25 m from the mirror, what is the height of the image?

3. What is the frequency of a 7 X 10^-25 joule photon?

Answer 1

• If an object is placed u= 1.65cm in front of a mirror and an image is formed v=6 cm in front of the mirror

so with the help of mirror formula we can get

is the focal length of the mirror.

• Now, a o=2.1m tall object is placed u=8.5m infront of a truck mirror or convex mirror to form an image v=-1.25 m from the mirror

Using the mirror height formula for convex mirror we get

so the height of the image would be 0.336 m

• Frequency of a photon in terms of energy is where h is the Planck's constant i.e,h=6.626 X 10^-34 J s

Given energy is E=7 X 10^-25 J

So the frequency is