Answer:
1. 
2. 
Explanation:
Given:
length of copper cable, 
diameter of copper cable, 
current through the copper wire, 
We have the resistivity of copper, 
<u>We know that the resistance of a wire is given as:</u>

where:
cross sectional area of the wire


1.
<u>Now from the Ohm's law:</u>



2.
<u>From the Joules law the thermal energy generated as an effect of electrical energy is mathematically given as:</u>
<u />
where:
time duration for which the current flows
(∵ we have 3600 seconds in 1 hour)

To solve this problem it is necessary to apply the concepts related to the change of Energy in photons and the conservation of energy.
From the theory we could consider that the energy change is subject to

Where
Initial Energy
Energy loses
Replacing we have that


Therefore the Kinetic energy of the electron once it has broken free of the metal surface is 0.8eV
Object B is positively charged, Object C is negatively charged, Object D is negatively charged.
Answer:
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