<span>b. becomes weaker
try this </span>
It is B. false that an instrument used to detect a static electric charge is called an ammeter. It is actually called an electroscope. Ammeter measures current.
Answer:
Current in outer circle will be 15.826 A
Explanation:
We have given number of turns in inner coil 
Radius of inner circle 
Current in the inner circle 
Number of turns in outer circle 
Radius of outer circle 
We have to find the current in outer circle so that net magnetic field will zero
For net magnetic field current must be in opposite direction as in inner circle
We know that magnetic field is given due to circular coil is given by

For net magnetic field zero

So 

Answer:
The tension is 
Explanation:
From the question we are told that
The total mass is 
The radius is 
The density of air is 
Generally the upward force acting on the balloon is mathematically represented as

=> 
=> 
Here V is the volume of the spherical helium filled balloon which is mathematically represented as

=> 
=> 
So

