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Practice Problems -Test 3
1.
What is the time constant of the circuit, with R=2 Ohms and C= 2 microFarads.
2.
A 2.0 microFarad capacitor is changed to 10 V. It is then connected acrossa 500 kiloOhms resistor. How long does it take (i) for the capacitor voltage to reach 5 V and (ii) for the energy stored in the capacitor to decrease to 1/3 its initial value?
3. What power dissipation must resistor R3 be able to tolerate? (see cuircut shown in the Textbook page 701)
4.
What is the minimum magnetic field needed to exert a 5.4x10-15 N force onan electron moving at 3x107 m/s?
5.
A particle carrying a 30 microCoulomb charge moves with velocity v= 5 i + 3.2 km/s through a uniform magnetic field B= 9.4 i + 6.7 j T. What is the force on the particle?
6.
A 2.0 m long wire has a mass of 37 g. The wire extends horizontally, at 45 deg.to a horizontal magnetic field of 0.08 T. What current in the wire will result in the magnetic force suspending it against gravity?
7.
You have 20 m of 0.5 mm diameter copper wire and a battery capable of passing 15 A through wire. What magnetic field strengths could you obtain inside a 2 cm diameter solenoid wound with the wire as closely spaced as possible?
8.Two long, parallel wires are 6.0 cm apart. One carries 3 A and the other 6 A, with both currents in the same direction. Where on a line perpendicular to both wires is the
magnetic field zero?
9.
A wire of length L carries current I as shown (page 781, problem 59). Point A lies on the perpendicular bisector, a distance y from the wire. Show that magnetic field at A due to straight wire alone has magnitude. What is the field direction?
10.
A toroidal coil of inner radius 15 cm and outer radius 17 cm is wound from 1500 turns of wire. What is the maximum magnetic field strength within the toroid when it carries a 10 A current?
 
bhatti@panam.edu
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