How does mirror equation works

Topic:- mirror equation

Ray diagrams can be used to determine the image location, size, orientation and type of image formed of objects when placed at a given location in front of a mirror.
The reflection of light is what we are getting here.

Let us see one example on it .

Question:-
An object is 15 cm from a spherical concave mirror having a 20 cm radius. Locate the image by means of: the mirror equation?

ANSWER: - 30 cm

The mirror equation expresses the quantitative relationship between the object distance (do), the image distance (di), and the focal length (f). The equation is stated as follows:

1/ do +1/f = 1/ di

f=-r/2= - 20/2=-10 cm

So here di = - 30 cm

Here the image is – 30 cm from the mirror

Question on Wavelength of Sound generated by a String

Waves and Sounds is one of the basic concept in Physics which deals with wavelength, frequency and velocity of waves and sounds under uniform motion.

Topic : Velocity and Wavelength of Sound

Waves travel under uniform motion in sinosoidal form. However velocity of waves will be calculated using same formula v = s/t where s is the distance between two crests of wave denoted by λ.

Question : The velocity of waves on a string is 92 m/s. If the frequency of standing waves is 475 Hz, how far apart are two adjacent nodes?

Solution :
The distance between two adjacent nodes is the half of wavelength.
Therefore:
λ = v/f
= 92/475
= 0.2m

Therefore: d = λ/2 = 0.1 m

For more simple word problem like this contact physics help or science help.