Answer:
a
The magnetic field strength is 
Explanation:
From the question we are told that
The length line above the ground is 
The current of the line is 
The voltage of the line is 
Generally magnetic field strength is mathematically represented as

Where
is the permeability of free space 

![= (2.0*10^{-7})[\frac{200}{20} ]](https://tex.z-dn.net/?f=%3D%20%282.0%2A10%5E%7B-7%7D%29%5B%5Cfrac%7B200%7D%7B20%7D%20%5D)


Earths magnetic field is approximately given as 
So the percentage would be


%
Answer:
F'= 4F/9
Explanation:
Two small objects each with a net charge of +Q exert a force of magnitude F on each other. If r is the distance between them, then the force is given by :
...(1)
Now, if one of the objects with another whose net charge is + 4Q is replaced and also the distance between +Q and +4Q charges is increased 3 times as far apart as they were. New force is given by :
.....(2)
Dividing equation (1) and (2), we get :

Hence, the correct option is (d) i.e. " 4F/9"
Answer:
Explanation:
As the circuit is parallel, then there is no effect of other branches as the potential difference across each arm is same.
Explanation:
A double replacement reaction is a reaction in which two different compounds are mixed together and both their cations and anions get exchanged with each other respectively.
When potassium bromide reacts with silver nitrate then it results in the formation of potassium nitrate and silver bromide.
The chemical reaction equation is as follows.
