A air-filed solenoid 3.3 m diameter and length 23 cm, has 100 turns. If the current increases from 9 mA to 43 mA in 0.3 s a) What is the inductance of the solenoid? b) What is the induced emf? c) What is magnetic field of solenoid for 15 mA?

What is the magnetic field due to an inductor of length 10 cm that has300 turns if 0.25 A of current passes through it? What is its inductance ifthe cross sectional area of the inductor is 1.5 cm2?

plz help Inductive battery chargers, which allow transfer of electrical power without the need for exposed electrical contacts, are commonly used in appliances that need to be safely immersed in water, such as electric toothbrushes. Consider the following simple model for the power transfer in an inductive charger (see the figure).(Figure 1) Within the charger's plastic base, a primary coil of diameter ddd with nPnP turns per unit length is connected to a home's ac wall outlet so that a current I=I0sin(2πft)I=I0sin(2πft) flows within it. When the toothbrush is seated on the base, an NNN-turn secondary coil inside the toothbrush has a diameter only slightly greater than ddd and is centered on the primary. Find an expression for the emf induced in the secondary coil. [This induced emf recharges the battery.] Express your answer in terms of the variables ddd, nPnPn_P, I0I0I_0, fff, ttt, NNN, and appropriate constants.

4. A coil of current carrying wire contalns 500 turns and is 20cm long with a diameter of 2cm. What is its inductance? What is the magnetic flux through It with a current of 20 A running through the wire? What is the induced voltage across it if the 20a current dies to zero at a constant rate during a 10second interval? VLE