here the charge density of metal plate is given as

now the electric field is given Gauss law

now here E = constant
so we will have

Since total area on both sides of plate will be double and becomes 2A



Now if we will find the electric field inside the metal plate
Then as we know that total charge inside the plate will always be zero
so we have

The compass is designed and developed to use a pendulous system to improve horizontality.
<h3>What is a compass?</h3>
A compass can be defined as a scientific instrument that contains a magnetized pointer, which is used to show and indicate the following four (4) main cardinal directions:
Basically, the compass is a scientific instrument that's designed and developed to use a pendulous system to improve horizontality.
Read more on compass here: brainly.com/question/11165627
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10,000 meters: 1,000 meters in every kilometer.
Answer:
120,000J
Corrected question;
In one hour, coal supplies 500 000 J of energy. The wasted energy amounts to 380 000 J. How much useful energy is produced in one hour?
Explanation:
Given;
Total energy Et = 500,000 J
Wasted Energy Ew = 380,000J
The amount useful energy is the amount of energy that is available for supply.
This can be derived by subtracting the wasted energy from the total energy.
Useful energy = Total Energy - wasted energy
Eu = Et - Ew
Substituting the given values;
Eu = 500,000J - 380,000
Eu = 120,000 J
The amount of useful energy produced in one hour is 120,000 J