asked 220k views
2 votes
An emf of 17 mV is induced in a 314-turn coil when the current is changing at a rate of 14.5 A/s. What is the magnetic flux through each turn of the coil at an instant when the current is 2.09 A?

asked
User EnterML
by
7.6k points

1 Answer

2 votes

Sure, we can solve this problem by using Faraday's law of electromagnetic induction.

Step 1: Convert the EMF into volts. As we're given 17 mV (millivolts), we convert it to volts by multiplying by 10^-3. So, 17 mV = 17 * 10^-3 = 0.017 V.

Step 2: Write down the other given quantities. There are 314 turns on the coil and the current is changing at a rate of 14.5 A/s.

Step 3: Apply Faraday's law of electromagnetic induction. The emf (electromotive force) in a circuit is equal to the negative rate of change of magnetic flux through the circuit (emf = -d(phi)/dt). The minus sign is a result of Lenz's law, which states that currents are induced in such a way as to oppose the change causing them.

Step 4: Substitute the values into the formula. To find the magnetic flux, ϕ (in Weber, Wb), through each turn of the coil, we rearrange Faraday's law to give:

ϕ = -emf / turns / rate of change of current


We substitute our given values into the equation to find:

ϕ = -0.017 / 314 / 14.5

Step 5: Solve for ϕ to give the magnetic flux per turn. Using a calculator, we find ϕ is approximately equal to -3.73 x 10^-6 Wb. This is the magnetic flux through each turn of the coil at the instant when the current is 2.09 A.

Please note, having a negative result for the magnetic flux is completely normal in this situation because of Lenz’s law. What's important is the magnitude of this flux, not its sign. The negative sign simply indicates that the flux is decreasing.

answered
User Emmics
by
8.2k points
Welcome to Qamnty — a place to ask, share, and grow together. Join our community and get real answers from real people.