Physics 1102 In-Class Problems: DC Circuits and Kirchhoff's Rules

1. Use the loop method to find current through each resistor in the circuit shown below.
   
   

2. Use the loop method to find current through each resistor in the circuit shown below.
   
   

3. Use the branch method to find current through each resistor in the circuit shown below. Find the potential difference between points A and B.
   
   

4. Use the branch method to find current through each resistor in the circuit shown below. Find the potential difference between points A and B.
   
   

5. An electronic flash attachment for a camera produces a flash by using the energy stored in a 750-μF capacitor. Between flashes, the capacitor recharges through a resistor whose resistance is chosen so that the capacitor recharges with a time constant of 3.0 s. Determine the value of the resistance.

6. A charged capacitor is connected across a 9600-Ω resistor and discharges to 1% of its maximum charge in a time of 8.3 s. What is the capacitance of the capacitor?
   

7. Ideal capacitors have an infinite internal resistance. Real capacitors only have a very large resistance as charges leak from one plate to the other. If a capacitor of 8.0 μF has an internal resistance of 5.0 × 10⁸ Ω, how long does it take for one-half of its original charge to leak away?
   

8. Three identical capacitors are connected with a resistor in two different ways. When they are connected as in part a of the drawing, the time constant to charge up this circuit is 0.020 s. What is the time constant when they are connected with the same resistor as in part b?
   
   

9. In the circuit shown below, ε = 12.0 V, r = 0.500 Ω, R₁ = 5.00 Ω, R₂= 10.0 Ω, and C = 250 μF. Initially, the switch S is open. (a) At the instant S is closed, determine the current supplied by the battery. (b) After the switch has be closed for a long time, determine the current supplied by the battery. (c) What is the voltage drop and charge across the capacitor at this later time? (d) The switch is now reopened, how long does it take for the capacitor to lose 80% of its charge.
   

10. A galvanometer has a coil resistance of 250 Ω and requires a current of 1.5 mA for full-scale deflection. This device is used in an ammeter that has a full-scale deflection of 25.0 mA. What is the value of the shunt resistance?
    

11. The coil resistor in an ammeter has a resistance which is 100 times larger than the shunt resistor. The galvanometer reads 10.0 mA when the ammeter is used to measure the current in a simple circuit. Unfortunately, the resistor in the simple circuit has a resistance which is only 5.00 times as large as the shunt resistor. What would be current through the resistor if the ammeter was not in place?
    

12. A galvanometer with a full-scale deflection of 2000 μA has a coil resistance of 100 Ω. If it is to be used as a voltmeter with a full-scale deflection of 1.5 V, what would be the required multiplier resistance?
    

Questions? mike.coombes@kwantlen.ca