For a certain transverse wave, the distance between two successive crests is 1.20 m and eight additional crests pass a given point along the direction of travel every 13.00 s. calculate the wave speed.

The distance between two succesive crests of a wave corresponds to its wavelength, therefore the wavelength of this wave is


The frequency of a wave is the number of crests that passes through a given point in a certain time; therefore, for this wave it is:


And now we can calculate the wave speed, which is given by the product between the wavelength and the frequency:

The reflection of the candle in the concave mirror formed an upside-down virtual image that is smaller than the candle.in other words. the answer is the third option, c