<span>An atom’s emission of light with a specific amount of energy confirms that </span><span>electrons emit and absorb energy based on their position around the nucleus.
The light emitted from an electron is a result of the electron's quantum jumps/leaps ( atomic electron transitions ) to and from different energy levels.</span>
The reason why a delivery truck filled with birds sitting on the floor be heavier than a truck with the same birds flying around is because when the birds are sitting on the floor, they are adding their weight to the truck.
Meanwhile, if the birds are flying around they aren't resting on the truck or touching it, so therefore their weight wouldn't be added to the truck.
The mass of the truck will remain the same as you cannot change the mass but the weight will vary depending on the items and objects placed in it.
Gravity on the surface = 4 m/s^2
Now, the acceleration due to centripetal motion, a = v^2/R
Where,
v= 10^3 m/s, R = 10^6 m
Then,
a = (10^3)^2/(10^6) = 1 m^2/s
The net gravitational acceleration = 4-1 = 3 m/s^2
The reading on the spring scale = ma = 40*3 = 120 N
Answer:
The charge density in the system is 
Explanation:
To solve this problem it is necessary to keep in mind the concepts related to current and voltage through the density of electrons in a given area, considering their respective charge.
Our data given correspond to:

We need to asume here the number of free electrons in a copper conductor, at which is generally of 
The equation to find the current is

Where
I =Current
V=Velocity
A = Cross-Section Area
e= Charge for a electron
n= Number of free electrons
Then replacing,


Now to find the linear charge density, we know that

Where:
I: current intensity
Q: total electric charges
t: time in which electrical charges circulate through the conductor
And also that the velocity is given in proportion with length and time,

The charge density is defined as

Replacing our values


Therefore the charge density in the system is 