Blog

A 109  turn circular coil of radius  2.41  cm is immersed in a uniform magnetic field that is perpendicular to the plane of the coil. Over an interval of  0.159  s , the magnetic field strength increases from 58.3  mT to  98.3  mT . Find the magnitude of the average emf  induced in the coil during this time interval, in millivolts.

A simple ac circuit is composed of a capacitor connected across the terminals of an ac power source. If the frequency of the source is doubled, what happens to the reactance of the capacitor?

An ideal parallel-plate capacitor has a capacitance of  C. If the area of the plates is doubled and the distance between the plates is halved, what is the new capacitance?

A heart defibrillator being used on a patient has a resistance of [R] k  Ω and a capacitance of [C] μF.  If the initial voltage is 12.0 kV, how long does it take to decline to 600 V?

You are given a copper bar of dimensions 3 cm × 5 cm × 8 cm and asked to attach leads to it in order to make a resistor. If you want to achieve the  largest possible resistance, you should attach the leads to the opposite faces that measure

What charge accumulates on the plates of a 2.0-μF air-filled capacitor when it is charged until the potential difference across its plates is 100 V?

Three resistors with resistances of 2.0 Ω, 6.0 Ω, and 12 Ω are connected across an ideal dc voltage source  V as shown in the figure. If the total current through the circuit is  I = 2.0 A, what is the applied voltage  V?

What type of shimming uses shims to adjust for large changes in the magnetic field by manipulating the lines of flux?

Why is helium is the cryogen of choice in superconducting magnets?

An actress crossing the stage to accept her Oscar award trips on the hem of her gown, and the audience gasps.  When she reaches the microphone, she jokes that she didn’t have enough time to practice walking in the dress.  The audience laughs, and she continues with her acceptance speech.  What has occurred here?