The resistance of the piece of wire is

where

is the resistivity of the copper

is the length of the piece of wire

is the cross sectional area of the wire
By substituting these values, we find the value of R:

Then, by using Ohm's law, we find the potential difference between the two points of the wire:
32.5 kg of air
Explanation:
To calculate the mass of the air, we use the density formula:
density = mass / volume
mass = density × volume
density of air = 1.3 kg/m³
volume = 5 × 3 × 2 = 25 m³
mass of the air = 1.3 kg/m³ × 25 m³
mass of the air = 32.5 kg
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density
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Answer:
Explanation:
Plate separation, d = 1.76 cm = 0.0176 m
Area of plates, A = 25 cm^2 = 0.0025 m^2
V = 255 V
(a) Capacitance of capacitor


C = 1.258 x 10^-12 F
charge is same before and after immersion as the battery is disconnected
q = C V
q = 1.258 x 10^-12 x 255 = 3.2 x 10^-10 C
(b)
Capacitance before, C = 1.258 x 10^-12 C
capacitance after, C' = k x C = 80 x 1.258 x 10^-12 = 100.64 x 10^-12 C
Where, k is the dielectric constant of water = 80
Potential difference after immersion, V' = V / k = 255 / 80 = 3.1875 V
(c) initial energy,


Final energy

