Final answer:
To find the magnetic field strength needed to induce an average emf of 10,000 V, we can use Faraday's law of electromagnetic induction.
Step-by-step explanation:
To find the magnetic field strength needed to induce an average emf of 10,000 V, we can use Faraday's law of electromagnetic induction. Faraday's law states that the emf induced in a coil is directly proportional to the rate of change of magnetic flux through the coil.
The magnetic flux through the coil can be calculated using the formula: magnetic flux = magnetic field strength x area of the coil.
In this case, the coil has a radius of 0.250 m, so the area of the coil is pi x (0.250)^2. We can rearrange the formula to solve for the magnetic field strength, which gives us:
magnetic field strength = emf / (number of turns x rate of change of magnetic flux)
Using the given values, the magnetic field strength needed to induce the average emf of 10,000 V is approximately 0.12 T.