Answer: option 4: A wire that is 2-mm thick and coiled.
Explanation:
The current in each wire is same. The magnetic field due to a current carrying wire increases if the wire is coiled with the more number of turns. A thick wire would cause low resistance to the current. Hence, a 2-mm thick wire which is coiled would produce the strongest magnetic field.
Answer:

Explanation:
Given that,
Radius of a spherical shell, r = 0.7 m
Torque acting on the shell, 
Angular acceleration of the shell, 
We need to find the rotational inertia of the shell about the axis of rotation. The relation between the torque and the angular acceleration is given by :

I is the rotational inertia of the shell

So, the rotational inertia of the shell is
.
Im guessing it's (a) since the numbers go in chronological order and you read the periodic table left to right
Answer:
5773.50269 Hz
23 A
Explanation:
= Inductance = 6 mH
= Capacitance = 5 μF
= Resistance = 3 Ω
= Maximum emf = 69 V
Resonant angular frequency is given by

The resonant angular frequency is 5773.50269 Hz
Current is given by

The current amplitude at the resonant angular frequency is 23 A