Answer: False
Explanation: They can see it by karst topography!
D. The graduated cylinder is used to find the volume, and triple beam balance is used to find the mass.
Answer:
The magnitude of the magnetic field B is 5.921 T.
Explanation:
Given that,
Length = 4.1 mm



Current 
We need to calculate the magnetic field
Using formula of magnetic field

Put the value into the formula


Hence, The magnitude of the magnetic field B is 5.921 T.