Answer:

Explanation:
Let's use Ohm's law:
or
(1)
Where:

We know the value of the voltage V, so we need to find the value of R in order to find I. Fortunately there is a relation between the resistivity of a conductor and its electrical resistance given by:
(2)
Where:

Keep in mind that the electrical resistivity of the gold is a known constant which is
and the cross sectional area of the conductor is calculated as:

Because we have a wire in this case, so we assume a cylindrical geometry.
Now replacing our data in (2)

Finally, we know R and V, so replacing these values in (1) we will be able to find the current:

Answer:
Explanation:
Let the charge on proton be q .
energy gain by proton in a field having potential difference of V₀
= V₀ q
Due to gain of energy , its kinetic energy becomes 1/2 m v₀²
where m is mass and v₀ is velocity of proton
V₀ q = 1/2 m v₀²
In the second case , gain of energy in electrical field
= 2 V₀q , if v be the velocity gained in the second case
2 V₀q = 1/2 m v²
1/2 m v² = 2 V₀q = 2 x 1/2 m v₀²
mv² = 2 m v₀²
v = √2 v₀