Answer:
That is, mechanical waves cannot travel through a vacuum. This feature of mechanical waves is often demonstrated in a Physics class. A ringing bell is placed in a jar and air inside the jar is evacuated. Once air is removed from the jar, the sound of the ringing bell can no longer be heard.
Frequency represents the number of complete oscillations in one second. it is measured in Hertz (Hz). Electromagnetic waves are waves which do not require a material media for transmission. They travel with a speed of light.
The speed (m/s) of a wave is given by frequency (Hz) × Wavelength (m)
Speed is 300,000 km/sec or 300,000,000 m/s and the wavelength is 300,000 km or 300,000,000 m.
Frequency = speed÷ wavelength
= 300000000 ÷ 300000000 = 1
Therefore, the frequency of the wave is 1Hz
Answer:
ℏ
Given:
Principle quantum number, n = 2
Solution:
To calculate the maximum angular momentum, 
, we have:
(1)
where,
l = azimuthal quantum number or angular momentum quantum number
Also,
n = 1 + l
2 = 1 + l
l = 1
Now,
Using the value of l = 1 in eqn (1), we get:
ℏ
