Answer:
a. -8 cm
Explanation:
 = distance of the object = 4 cm 
 = distance of the image = ?
 = focal length of the converging lens  = 8 cm 
using the lens equation 


 = - 8 cm 
 
        
             
        
        
        
Answer:
(1) passed through the foil
Explanation:
Ernest Rutherford conducted an experiment using an alpha particle emitter projected towards a gold foil and the gold foil was surrounded by a fluorescent screen which glows upon being struck by an alpha particle.
- When the experiment was conducted he found that most of the alpha particles went away without any deflection (due to the empty space) glowing the fluorescent screen right at the point of from where they were emitted. 
 
- While a few were deflected at reflex angle because they were directed towards the center of the nucleus having the net effective charge as positive. 
 
- And some were acutely deflected due to the field effect of the positive charge of the proton inside the nucleus. All these  conclusions were made based upon the spot of glow on the fluorescent screen.
 
 
        
                    
             
        
        
        
Once the atomic number of an atom is known, the number of electrons can be deduced depending on if the atom is an ion or a neutral one.
<h3>Atomic number</h3>
The atomic number of an atom is the number of protons in the nucleus of the atom. 
For atoms that are neutral, that is, no net charges, the number of protons is always equal to the number of electrons. In other words, the positive charges always balance the negative charges in neutral atoms. 
Thus, if the atomic number of a neutral atom is 6, for example, the proton number will also be 6. Since the proton must balance the electron, the number of electrons will also be 6.
More on atomic numbers can be found here; brainly.com/question/17274608
 
        
             
        
        
        
This problem uses the relationships among current 
I, current density 
J, and drift speed 
vd. We are given the total of electrons that pass through the wire in 
t = 3s and the area 
A, so we use the following equation to to find 
vd, from 
J and the known electron density 
n,
 so: 

<span>The current
 I is any motion of charge from one region to another, so this is given by:
</span>

The magnitude of the current density is:

Being:

<span>
Finally, for the drift velocity magnitude vd, we find:
</span>
Notice: The current I is very high for this wire. The given values of the variables are a little bit odd
 
        
             
        
        
        
overuse of a muscle Answer:
Explanation: