Answer:
Explanation:
Given that,
The mutual inductance of the two coils is
M = 300mH = 300 × 10^-3 H
M = 0.3 H
Current increase in the coil from 2.8A to 10A
∆I = I_2 - I_1 = 10 - 2.8
∆I = 7.2 A
Within the time 300ms
t = 300ms = 300 × 10^-3
t = 0.3s
Second Coil resistance
R_2 = 0.4 ohms
We want to find the current in the second coil,
The same induced EMF is in both coils, so let find the EMF,
From faradays law
ε = Mdi/dt
ε = M•∆I / ∆t
ε = 0.3 × 7.2 / 0.3
ε = 7.2 Volts
Now, this is the voltage across both coils,
Applying ohms law to the second coil, V=IR
ε = I_2•R_2
0.72 = I_2 • 0.4
I_2 = 0.72 / 0.4
I_2 = 1.8 Amps
The current in the second coil is 1.8A
Answer:
A, B, and C are good reasons for my friend not to worry
Explanation:
The following reasons are reason not to worry
A. The only way to lose additional partial credit on a hint is by using the "give up" button or entering incorrect answers. Leaving the question blank will not cost you any credit (Regardless of whether you open a link or not, you will lose credit if you enter a wrong answer or if you give up on a question by hitting the "give up" button. Even after opening a hint, you can leave the question blank if the hint does not provide relevant hints or if the hint brings up more question. Once the question is left blank, you do not lose additional partial credit)
B. As an incentive for thinking hard about the problem, your instructor may choose to apply a small hint penalty, but this penalty is the same whether the hint simply gives information or asks another question (In a situation where you decide to use a hint, the instructor may have put a penalty for using the hint, so whether it asks a question or help in the solution of the question, as long as the hint is consulted, the hint penalty still applies)
C. Getting the correct answer to the question in a hint actually gives you some partial credit, even if you still can't answer the original question (An advantage of using hint is that you get some partial credit for using it if you answer the hint question correctly and fails to answer the original question)
