Answer:
Electric field will be
Explanation:
We have given diameter of the copper d = 2.05 mm
So radius
We know that area
Current is given as i = 4.7 A
So current density
Resistivity is given
We know that electric field is given by
Answer: For the given process it is true that the balloon has a net charge on it, but the wall may be neutral (have no net charge).
Explanation:
When we tend to rub a balloon against a woolen sweater then it is possible that the balloon might stick to the wall. This might be due to the increase in number of electrons on the balloon and the wall gets positively charged.
Since, opposite charges tend to attract each other hence, the balloon will stick to the wall.
A neutral object also tends to acquire a certain charge when it is rubbed by a charged object.
Therefore, we can conclude that the balloon has a net charge on it, but the wall may be neutral (have no net charge).
Answer:
A. Underground coal mining is dangerous because of possible tunnel collapse and possible methane gas explosions.
Explanation:
Dangers of underground coal mining include asphyxiation, methane gas poisoning, tunnel collapse and explosions of methane gas, a highly flammable gas. Methane explosions occur since this gas is a byproduct of coal. This explosion can cause tunnel collapse.
Answer:
less frequency in the energy