Answer
given,
Side of copper plate, L = 55 cm
Electric field, E = 82 kN/C
a) Charge density,σ = ?
   using expression of charge density
  σ = E x ε₀
 ε₀ is Permittivity of free space = 8.85 x 10⁻¹² C²/Nm²
now,
  σ = 82 x 10³ x 8.85 x 10⁻¹²
  σ = 725.7 x 10⁻⁹ C/m²
  σ = 725.7 nC/m²
change density on the plates are 725.7 nC/m² and -725.7 nC/m²
b) Total change on each faces 
    Q = σ  A
    Q = 725.7 x 10⁻⁹ x 0.55²
    Q = 219.52 nC
Hence, charges on the faces of the plate are 219.52 nC and -219.52 nC
 
        
             
        
        
        
Answer:
F = f from Newton’s first law.
Explanation:
 since the desk is moved in a straight line at a constant speed, newton first law tell us that the two forces must be equal.
Newton's First Law states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. since the table has been set in motion by the 400 N force, it will remain in motion unless it is been acted upon by an external force, and this means that the 400 N must be equal to the frictional force for it to have been in motion in the first instance.
 
        
             
        
        
        
Answer:
Power input, P = 2880 watts
Explanation:
It is given that,
Voltage of the motor, V = 240 V
Current required, I = 12 A
Weight lifted, W = 2000 lb
It is lifting at a speed of 25 ft/min. We need to find the power input to the motor. The product of current and voltage is called power input of the motor.


P = 2880 watts
So, the power input of the motor is 2880 watts. Hence, this is the required solution.
 
        
             
        
        
        
I think it’s C. Stroke if not then D
        
             
        
        
        
Technically this is a Biology question;
The 'amount' we can see depends on how much light can get through our pupil to hit our retina.
When there is a lot of light the pupil is small; it doesn't need to be big to let a lot of light in.
When we move to a dark space there is much less light, so the pupil 'dilates' to let enough light so we can see properly.
The period in which one cant see is simply when the pupil hasn't had time to change shape yet so doesn't let in enough light.<span />