Electricity and Magnetism Answers

In an LC circuit in which C = 4.0 uF the maximum potential difference across the capacitor during the oscillations is 1.5 V and the maximum current through the inductor is 50 mA. (a) What is the inductance L? (b) What is the frequency of the oscillations? (c) How much time does it take for the charge on the capacitor to rise from zero to its maximum value?

Find the emf induced in a 0.1-H coil when the current in it is changing at the rate of 80 A/s.

How fast should a wire 20 cm long be moved through a 0.05-T magnetic field for an emf of 1 V to appear across its ends? 

A 200-turn solenoid having a length of 25 cm and diameter of 10 cm carries a current of 0.30 A. What is the magnitude of the magnetic field B near the center of the solenoid?

What uniform magnetic field must be set up in space to permit a proton of speed 1.0x10^7 m/s to move in a circle the size of the earth’s equator? (R = 6400 km) 

 It is desired to have a current of 20 A in a 5- resistor when it is connected to an 80-V battery. Is there any way in which an auxiliary resistor can be connected in the circuit to increase the current in the 5- resistor to this valur? If so, what should ist resistance be?

A wire of resistance 5  is connected to a battery whose emf is 2 V and whose internal resistance is 1.0 . In 2.0 min (a) how much energy is transferred from chemical to electric form? (b) How much energy appears in the wire as thermal energy? (c) Account for the differences between (a) and (b). 

A write 4.0 m long and 6.0 mm in a diameter has a resistance of 96 . If a potential difference of 20 V is applied between the ends, (a) what is the current in the wire? (b) what is the current density? (c) what is the resistivity of the wire material? 

A 75-W hall light is left on continuously. At 0.04 Ls/kWh, find the cost per week.

If you have available several 2.0-uF capacitors, each capable of withstanding 200V without breakdown, how would you assemble a combination having an equivalent capacitance of (a) 0.40 uF or of (b) 1.2 uF, each capable of withstanding 1000 V?