A circuit has a 2.9 V battery connected in series with a switch. When the switch is closed, the battery powers two paths in parallel, one of which has a resistor of resistance R1 = 80 Ω in series with an inductor of inductance L = 1×10−2 H , while the other has a resistor of resistance R2 = 230 Ω . What is the current supplied by the battery at a time t = 0.25 ms after the switch is closed? What is the current i1 supplied by the battery a time t = 0.25 ms after the switch is closed? Express your answer in amperes to three significant figures.

A 100 Hz AC voltage source, with a peak output of 170 V, is connected to an inductor. If the rms current through the inductor is 1 A, what is the value of the inductor?

1. 1.9 H

2. 190 mH

3. 19 mH

4. 1.9 mH

A quantity of N molecules of an ideal gas initially occupies volume V. The gas then expands to volume 2V. The number of microscopic states of the gas increases in the expansion. Under which of the following circumstances will this number increases the most? ( i ) if the expansion is reversible and isothermal ( ii ) if the expansion is reversible and adiabatic ( iii ) the number will change by the same amount for both circumstances. Why ?

A potential difference of 3.60 V will be applied to a 33.00 m length of 18-gauge platinum wire (diameter = 0.0400inches). Calculate the current.

Calculate the current density.

Calculate the electric field.

Calculate the rate at which thermal energy will appear in the wire.

An AC generator supplies an rms voltage of 240 V at 50.0 Hz. It is connected in series with a 0.350 H inductor, a 3.60 μF capacitor and a 211 Ω resistor.

1. What is the impedance of the circuit?

2. What is the rms current through the resistor?

3. What is the average power dissipated in the circuit?

4. What is the peak current through the resistor?

5. What is the peak voltage across the inductor?

6. What is the peak voltage across the capacitor?

7. The generator frequency is now changed so that the circuit is in resonance. What is that new (resonance) frequency?

A certain super capacitor has a capacitance of 1.0F. The maximum voltage is 2.7 V. It is contained in a 8.00mm diameter can that is 13.00 mm long. It has two leads that are 3.50mm apart. It costs $0.29 when bought in bulk. How can such a large capacitance be made in a small container? The largest dielectric constant for oils is about 90. The largest dielectric constant is about 100,000 in material that costs $100,000/kg. Just describe the type of design (vacuum parallel-plate, dielectric parallel-plate, cylindrical, dielectric cylindrical, rolled parallel-plate, electrolytic, adjustable plate, etc.)

What is the energy density of the capacitor when fully charged?

A blow-dryer and a vacuum cleaner each operate with a voltage of 120 V. The current rating of the blow-dryer is 9.2 A, while that of the vacuum cleaner is 5.9 A. Determine the power consumed by (a) the blow-dryer and (b) the vacuum cleaner. (c) Determine the ratio of the energy used by the blow-dryer in 18 minutes to the energy used by the vacuum cleaner in 56 minutes.

Three loads are connected in parallel to an AC supply of 120∠0° V. The loads are 40∠30° Ω, 50 - j30 Ω
and 30 + j40 Ω.
a) Draw the circuit diagram
b) Determine the amplitude and phase angle of the supply current graphically by constructing a
phasor diagram using a suitable scale of the load currents and source voltage.
c) State the overall power factor using the answer from part (b).
d) Construct another phasor diagram for the system that illustrates an improved power factor to
unity.
e) Determine the VAR rating of the load required to achieve this using its current phasor determined
graphically from part (d). State its capacitance or inductance.
f) Draw the power triangles for the system before and after power factor correction.

5. A proton and an electron are in a uniform electric field with magnitude 45 V/C. Which particle has the larger magnitude acceleration, and what is the magnitude of the acceleration? (e = 1.6×10−19 C, mp = 1.67×10−27 kg, me = 9.11×10−31 kg) A. the electron, 7.9×1012 m/s2 B. the proton, 4.3×1013 m/s2 C. the proton, 4.3×109 m/s2 D. the electron, 7.9×108 m/s2 E. the electron, 7.9×1010 m/s2

6. A +2q point charge is located at the origin (x = 0), and a –3q charge is at x = +d. What is the magnitude of the electric field at x = +2d ? Assume 1 4π0 = k. A. 7kq 2d2 B. 5kq 2d2 C. 4kq d2 D. 3kq 2d2 E. 5kq d2