Download Drill Problems

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PHYS 202 DRILL HOMEWORK PROBLEMS
PART 1
D1-1. An object has a net charge of –25 C. Does it have more electrons or protons and how many more?
[1.5625x1014 more electrons]
D1-2. An object has a net charge of +4 nC. Does it have more electrons or protons and how many more?
[2.5x1010 more protons]
D1-3. A +2 nC point charge is located at the origin of the xy-plane. A +3 nC point charge is located at
coordinates (2m, -1m). Find the size and direction of the electric force on the +3 nC charge.
[10.8 nN, -26.6]
D1-4. A –2 C point charge is located at coordinates (-1m, 3m). A +2 C point charge is located at
coordinates (2m, 1m). Find the size and direction of the electric force on the negative charge.
[2.77 mN, -33.7]
D1-5. A +5 nC point charge is located at the origin. Find the size and direction of its electric field at the point
(-4m, 3m).
[1.8 N/C, 143]
D1-6. A –4 C point charge is located at the point (2m, -1m). Find the size and direction of its electric field at
the point (-4m, 0).
[973 N/C, -9.5]
D1-7. An electron is at a point where the electric field is 2000 N/C directed at 240. Find the electric force on
the electron.
[3.2x10-16 N, 60]
D1-8. A +5 nC point charge feels an electric force of 1.5x10-5 N directed at 50. Find the size and direction of
the electric field at the position of the point charge.
[3000 N/C, 50]
D1-9. The electric field between two parallel plates is 4500 N/C. An electron starts from rest and is
accelerated across the plates in 2 nanoseconds. Find the acceleration of the electron and the distance
between the plates.
[7.9x1014 m/s2, 1.58 mm]
D1-10. The voltage difference between two parallel plates is 100V. The plates are separated 0.5 cm with the
left plate being at the higher voltage. Find the size and direction of the electric field between the plates.
[20000 V/m, points to the right]
D1-11. An electron is accelerated from rest between the plates in problem D1-10. In which direction does it
travel and what is its speed when it reaches the final plate?
[travels to the left with a final speed of 5.93x106 m/s]
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D1-12. An electron is accelerated between two parallel plates. It starts from rest and reaches a final speed of 107
m/s. Find the voltage difference between the plates.
[285 V]
D1-13. A capacitor is made out of two round plates separated by 0.5 mm. Each plate has a radius of 5 mm.
The space between the plates is filled with Teflon, which has a dielectric constant of 2.1. Find the
capacitance of the capacitor.
[2.9 pF]
D1-14. A 2.2 F capacitor is connected to a 10 V battery. Find the amount of charge stored on one of the
capacitor plates and the energy stored in the capacitor.
[22 C, 110 J]
D1-15. You hook up two 5 nF capacitors in series to a 1.5 V battery. Find the equivalent capacitance of your
circuit, the total charge moved by the battery, and the total amount of energy stored by the capacitors.
[2.5 nF, 3.75 nC, 2.8 nJ]
D1-16. You hook up two 5 nF capacitors in parallel to a 1.5 V battery. Find the equivalent capacitance of your
circuit, the total charge moved by the battery, and the total amount of energy stored by the capacitors.
[10 nF, 15 nC, 11.2 nJ]
D1-17. A current of 3 Amps flows past a point in a wire. How much charge passes this point in 2 nanoseconds?
How many electrons pass this point in 2 nanoseconds?
[6 nC of charge, 3.75x1010 electrons]
D1-18. If 1018 electrons flow past a point each second, how may milliamps is this current?
[160 mA]
D1-19. A resistor made out of a thin carbon wire has a radius of 0.32 mm (22 gauge wire) and a length of 20
mm. The resistivity of carbon is 3.5x10-5 -m. Find the resistance of the resistor.
[2.2 ]
D1-20. A 500  resistor is connected to a 10 V battery. Find the amount of current flowing through the resistor
and the power dissipated by the resistor.
[20 mA, 0.2 W]
D1-21. You hook up two 1000  resistors in series to a 9 V battery. Find the equivalent resistance of your
circuit, the total current supplied by the battery, and the total power dissipated by the resistors.
[2 k, 4.5 mA, 40.5mW]
D1-22. You hook up two 1000  resistors in parallel to a 9 V battery. Find the equivalent resistance of your
circuit, the total current supplied by the battery, and the total power dissipated by the resistors.
[500 , 18 mA, 162 mW]
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D1-23. For the circuit below, find the total current flowing from the battery and the total power supplied by the
battery.
[125 mA, 625 mW]
75 
50

5V
125 
D1-24. Find the currents through the three resistors in the circuit in Problem D1-23.
[100 mA (50 ), 25 mA (75 ), 25 mA (125 )]
D1-25. Find the power dissipated by each of the three resistors in the circuit in Problem D1-23.
[500 mW (50 ), 46.9 mW (75 ), 78.1 mW (125 )]