What is the speed of an electromagnetic wave that has a frequency of 7.8x106
Hz?

The speed of electromagnetic wave that has a frequency of Hz is m/s.

Electromagnetic waves:

Higher-frequency electromagnetic waves have less energy. All electromagnetic waves travel across space at the speed of light which is   m/s.

As we know that,

Speed=frequency x wavelength,

It follows that the wavelength will also not change. So the direction, speed, frequency and wavelength of any electromagnetic wave are constant and these properties will not change after emission from a source.

Thus, speed of an electromagnetic wave is fixed and does not change on varying frequencies which is m/s.

OR

The waves travel at the same speed, but the observed frequency depends on any relative motion between the observer and source.

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3. x 10⁸m/s

Explanation:

Given parameters:

Frequency of wave  = 7.8 x 10⁶Hz

Unknown:

Speed of the wave = ?

Solution:

All electromagnetic radiation has  a speed of 3. x 10⁸m/s in free space.

No matter the frequency and wavelength, they all have the same speed which is the same as the speed of light.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3