To determine the devices' order from greatest magnetic field strength to weakest, we need to calculate the magnetic field strength for each device. The magnetic field strength is influenced by the number of wire loops, the current, and whether or not there is a metal core. Specifically, the magnetic field strength is directly proportional to the product of the number of wire loops and the current, and it is doubled if there is a metal core.
1. Device W:
- Number of Wire Loops: 60
- Current: 0.0 mA
- Metal Core: Yes
- Magnetic Field Strength: [tex]\( 60 \times 0.0 \times 2 = 0 \text{ (since current is 0)} \)[/tex]
2. Device X:
- Number of Wire Loops: 40
- Current: 0.2 mA
- Metal Core: Yes
- Magnetic Field Strength: [tex]\( 40 \times 0.2 \times 2 = 16 \)[/tex]
3. Device Y:
- Number of Wire Loops: 30
- Current: 0.1 mA
- Metal Core: No
- Magnetic Field Strength: [tex]\( 30 \times 0.1 \times 1 = 3 \)[/tex]
4. Device Z:
- Number of Wire Loops: 20
- Current: 0.1 mA
- Metal Core: No
- Magnetic Field Strength: [tex]\( 20 \times 0.1 \times 1 = 2 \)[/tex]
Now, we arrange these devices in order from greatest to weakest magnetic field strength:
- Device with the greatest magnetic field strength: X (16)
- Next: Y (3)
- Next: Z (2)
- Weakest: W (0)
Thus, the correct order from greatest to weakest magnetic field strength is: X, Y, Z, W.
Therefore, the answer is:
- [tex]\( \boxed{X, Y, Z, W} \)[/tex]
