Answer:

Explanation:
Since we know that two sphere is oppositely charged so net electric field at the mid point of two balls will be sum of the electric field due to each ball at the mid point
So we know that

here we know that



so we have


Answer:
Explanation:
Given
Voltage 
Work done 
Work is Equivalent to energy
We know that Charge is given by

where I=current
t=time
Energy 
P=power
P=V\times I
V=Voltage
I=current
Also Energy 

Substitute the value of I in charge



Answer:
The required wavelength is 1.19 μm
Explanation:
In the double-slit study, the formula below determines the position of light fringes
on-screen.

where;
m = fringe order
d = slit separation
λ = wavelength
D = distance between screen to the source
For the first bright fringe, m = 1, and we make (d) the subject, we have:


replacing the value from the given question, we get:

In the double-slit study, the formula which illustrates the position of dark fringes
on-screen can be illustrated as:

The value of m in the dark fringe first order = 0
∴


making λ the subject of the formula, we have:

