Answer:

Explanation:
The energy of a photon is given by:

where
h is the Planck constant
f is the frequency of the photon
In this problem, we have:

is the frequency of the photon
Substituting into the equation, we find:

Answer:
at the stone age people thought that every thing in the earth is made up of 5 elements they are:-air,earth,fire,sky and water
Explanation:
Answer:(1)=current (2)=force (3)=magnetic field (4)=reverse
Explanation:When there's a current in The coil. A force act on each side Of The coil. This is because the coil is in a magnetic field, the direction Of The spin would reverse
The original frequency of horn of Car A is 1071 Hz.
Explanation:
Doppler effect describes the change in the frequency of sound waves with respect to the observer. As the sound waves emitted from a source need to travel the air medium to reach observer, it will undergo loss in energy. So there will be change in its frequency compared to original frequency. Depending upon the direction of travel of source and observer the shifting of frequency will vary.

Here vo is the observer velocity and vs is the velocity of the source. So Vo = 15 m/s as car B is the observer and Vs = 35 m/s as car A is the source. And f is the frequency of sound wave at source that is car A.
Similarly, the doppler shift in frequency is the frequency of sound heard by car B which is f' = 1140 Hz. And v is the speed of sound that is v = 343 m/s
1140 = 
f = 1140/1.0649= 1071 Hz.
Thus, the original frequency of horn of Car A is 1071 Hz.