A copper transmission cable 140 {\rm km} long and 12.5 {\rm cm} in diameter carries a current of 115 {\rm A}.

1.What is the potential drop across the cable?
2.How much electrical energy is dissipated as thermal energy every hour?

1.

2.

Explanation:

Given:

length of copper cable,

diameter of copper cable,

current through the copper wire,

We have the resistivity of copper,

We know that the resistance of a wire is given as:

where:

cross sectional area of the wire

1.

Now from the  Ohm's law:

2.

From the Joules law the thermal energy generated as an effect of electrical energy is mathematically given as:

where:

time duration for which the current flows

(∵ we have 3600 seconds in 1 hour)

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force