[PDF]

1. The circuit shown in the figure contains four resistors R1, R2, R3 and R4. The values are as follows: R1 =100 Ω; R4 =50 Ω. R3 is a variable resistor. R2 is a resistor whose value is unknown and which we wish to determine. When resistor R3 is 60 Ω, the ammeter connected between C and D does not show any current flowing through.

a) What is the voltage drop between C and D?

b) What is the value of R2?

2. We have a coil of copper wire and we wish to cut a piece that has a resistor of 1 Ω. What details are missing to enable us to carry out this operation? Calculate the characteristics of the conductor for the details provided.

3. Three equal resistors of 5 Ω each are combined forming a triangle. A voltage drop in 15 V is applied between two of the sides of this triangle. What current does flow through each of the resistors?

4. The voltage drop between the ends of resistor R1 shown in the figure is 50 V. Calculate:

a) The current through resistors R2, R3 and R4

b) The voltage drop on a resistor R2

 

5. Determine the equivalent resistor of the network in the following figure. What is the voltage drop between A and B if the ammeter shows 1 A?

6. Two groups of lamps are assembled in series. Each group composes of six lamps that are the same and are connected in parallel. A voltage drop of 200 V is applied between the ends of the assembled circuit.

Knowing that the resistor of each lamp is 180 Ω, calculate:

a) The voltage drop in each of them

b) The current that flows through each of them

c) If two lamps from each group are disconnected, what is now the current that flows through each of them?

7. Given the circuit shown in the figure:

a) Measure the total resistor of the circuit

b) Do a screen capture for the circuit

c) Calculate the voltage drop of 1 KΩ resistor

d) Calculate the voltage drop of 10 KΩ resistor

8. Given the circuit shown in the figure:

a) Measure the total resistor of the circuit

b) Do a screen capture for the circuit

c) Calculate the voltage drop between A and B (V_ab)

d) Calculate the voltage drop between B and C (V_bc)

 

This circuit is presented in Falstad in the below figure.

 

 

Other Exercises

1. The needle of a very sensitive ammeter shows 10mA with the internal resistor R1= 50 Ω.

a) What resistor R2 needs to be connected to the device and in what way in order to transform it into an ammeter capable of measuring current up to 10 A?

b) And if we want to convert it into a voltmeter capable of measuring voltage of 100 V?

2. One ampere-hour (Ah) refers to the amount of electricity transmitted in 1 hour via a constant 1A electrical current. Calculate:

a) The Ah charge in Coulomb;

b) The charge transmitted via an electrical current of 100mA in 20 minutes (expressed in Ah)

3. A car battery has a 36 Ah capacity (the charge it can provide us when totally discharged). The motor starter is switched on for 2 sec to start a car. It is fed by a 90 A current. How many times could we activate motor starter without recharging the battery? (the battery may run out when its capacity goes below 5 Ah)