f' = frequency observed by the police car after sound reflected from the vehicle and comes back to police car = 1250 Hz
f = frequency emitted by the police car = 1200 Hz
V = speed of sound = 340 m/s
v = speed of vehicle = ?
frequency observed by the police car is given as
f' = f (V + v)/(V - v)
inserting the values in the above equation
1250 = 1200 (340 + v)/(340 - v)
v = 6.9 m/s
Answer:
The photoelectric effect occurs only for frequencies above the cutoff frequency, regardless of the intensity.
Explanation:
The photoelectric effect occurs when light is shined on metals such as zinc beyond a certain frequency (the threshold frequency), which causes electrons to escape from the zinc. The electrons which are fleeing are called photo electrons.
Therefore photo electric effect is
The photoelectric effect occurs only for frequencies above the cutoff frequency, regardless of the intensity.
The hypothesis because its very hard to make and it confounds me
Answer:
Chemical bonds
Explanation:
The chemical bonds hold the different type atoms or ions together.
The type of chemical bonds :
1. Ionic bond ;
Ions or atoms changes the electron and form ionic bond.Those atoms gains the electron gets negative charge and those atoms donate the electron gets positive charge.
2.Covalent bond :
In this type of bond atoms share the electrons and form covalent bonds.
3. Metallic bond :
This type of bond are present in the metals.In this atoms are used free electrons to form bonds.
Therefore answer is --
Chemical bonds
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