DC Circuits - Check Point#1

A battery has an emf of 8 𝑉 and an internal resistance 2 𝛺. If it is connected to an external circuit that draws 6 𝑊 of power, what is a possible current in the circuit?

• 1𝐴

• 2𝐴

• 4𝐴

• 6𝐴

• 8𝐴

A battery with an internal resistance of 4 𝛺 is connected to a 40 𝛺 resistor to which it delivers 3 𝐴 of current. What is the emf of the battery?

• 92𝑉

• 120𝑉

• 132𝑉

• 160𝑉

• 240𝑉

A battery with emf 6.0 𝑉 and an internal

resistance 𝑟 is connected to a resistor of resistance 𝑅, as shown in Figure 1 below. The current in the circuit is 2.0 𝐴. When an identical battery is added to the circuit in series, as shown in Figure 2, the current in the circuit is 3.0 𝐴. Which of the following statements about the resistances in the circuit is true?

• 𝑟 is very small compared to 𝑅

• 𝑟 is very large compared to 𝑅

• 𝑟 is equal to 𝑅

• 𝑟 is one fourth of 𝑅

• 𝑟 and 𝑅 are comparable in magnitude, but they are not equal

A 10𝛺, 15𝛺 and 40𝛺 resistors are connected as shown to a 48 𝑉 emf source with internal resistance 𝑟 = 1 𝛺. What is the terminal voltage of the emf source?

• 0 V

• 43 V

• 46 V

• 47 V

• 48 V

• A

• B

• C

• D

• E