Introductory Physics Volume Two

182 Hints A
3.16 Compute the total charge that can flow from the battery. One
kilowatt hour is a unit of energy 3600kJ.
3.17 From the specific heat of water you can find the energy required
and from this you can find the power and thus from the known voltage
you can find the current and then resistance.
3.18 The internal resistance acts like it is in series with the external
resistor and and ideal voltage source.
3.19 Reduce the system in stages. Look for pairs of resistors in the
system that are in parallel or in series, combine this pair, then repeat
until there is only one resistor left.
3.23 Write out all of the equations and then solve.
3.25 Connect the circuit to a voltage supply V S and using Kirchhoff’s
rules for the resultant circuit you can find the charge on each capacitor.
This will in turn allow you to compute the total charge drawn form the
power supply and thus the effective capacitance of the system.
3.26 Use Kirchhoff’s rules
3.27 Use Kirchhoff’s rules
3.28 The bulb that draws the most power is brighter.
3.29 The appliances are connected in parallel to the voltage supply.
3.30 Use the result of the other problem in which you computed the
resistance of a 12 gauge copper wire.
3.31 The amount of heating is proportional to the power dissipated
by the wire per length.
3.32 When the capacitor is fully charged, no current flows into it.
4.1
(a) Notice that ⃗ dl has length Rdθ and is perpendicular to the radius
vector.
4.2 Compute the force on each of the fours section of wire first. Recall
that torque is ⃗τ = ⃗r × ⃗ F , where ⃗r points from the axis of rotation to
the point at which the force is applied.
4.5 For any radius it will take a time 2πm/qB
4.6 Plug the given values into the Lorentz force formula and do the
cross product.
4.7 The magnetic field of the earth points roughly northward.
4.8 Don’t forget that the electron is negatively charged.
4.9 This question is asking you to relate acceleration and force so
start with Newton’s second law.