Physics 1100 In-Class Problems: DC Circuits

1. In the diagram below, R₁ = 5 Ω, R₂ = 10 Ω, and R₃ = 15 Ω. The battery supplies an emf of ε = 0.30 V. What is the equivalent resistance, R_S? What is the current through each resistor? What is the voltage drop across each resistor? What is the power expended in each resistor?

2. In the diagram below, R₁ = 5 Ω, R₂ = 10 Ω, and R₃ = 15 Ω. The battery supplies an emf of ε = 0.30 V. What is the equivalent resistance, R_P? What is the voltage drop across each resistor? What is the current through each resistor? What is the power expended in each resistor?

3. For the circuits shown below, identify all nodes and branches. Are any nodes at the same potential? Which resistors, if any, are in series? Which resistors, if any, are in parallel?

   (a)
   (b)

4. Find the equivalent resistance of the circuit shown below. Find the voltage drop over, current through, and power dissipated by each resistor. Put your results in a table.
   

5. Find the equivalent resistance of the circuit shown below. Find the voltage drop over, current through, and power dissipated by each resistor. Put your results in a table.
   

6. Find the equivalent resistance of the circuit shown below. Find the voltage drop over, current through, and power dissipated by each resistor. Put your results in a table.

7. A student is working with the circuit shown in the diagram below. She uses an ammeter and finds that the current through the branch with the 300-Ω resistor to be I = 0.050 A.
   (a) What is the voltage drop across the 300-Ω resistor?
   (b) What is the voltage drop across the 150-Ω resistor?
   (c) What is the current through the 150-Ω resistor?
   (d) What is the current through the 100-Ω resistor?
   (e) What is the voltage drop across the 100-Ω resistor?
   (f) What is the emf of the battery?
   
8. A galvanometer has a coil resistance of 250 Ω and requires a current of 1.5 mA for full-scale deflection. This device is to be used in an ammeter that has a full-scale current of 25.0 mA. What is the value of the shunt resistance? What is the equivalent resistance of the ammeter?
9. Consider the circuit in diagram (a) below. What is the current in this circuit? Now consider the circuit in diagram (b) below. The only difference is that an ammeter has been added so that the current could be measured. The ammeter is the same one as the previous problem. What is the current reading on the ammeter? Why is it different from the theoretical value that you found for diagram (a)?
   

10. The equivalent resistance of a voltmeter is 140,000 Ω. The voltmeter uses a galvanometer that has a full-scale deflection of 180 μA. What is the maximum voltage that can be measured by the voltmeter?
11. Consider the circuit in diagram (a) below. What is the potential difference over the 140 kΩ resistor in this circuit? Now consider the circuit in diagram (b) below. The only difference is that a voltmeter has been added so that the potential difference could be measured. The voltmeter is the same one as the previous problem. What is the voltage reading on the voltmeter? Why is it different from the theoretical value that you found for diagram (a)?
    

Questions?mike.coombes@kwantlen.ca