Electric circuit problem, finding internal resistance

  • Thread starter physics604
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  • #1
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1. A battery whose emf is 6.0 V is connected to a 2.0 Ω resistor. The voltage drop across the 2.0 Ω resistor is 5.0 V. What is its internal resistance?

a) 0.40 Ω
b) 1.7 Ω
c) 2.4 Ω
d) 2.5 Ω



Homework Equations



VT=ε-Ir

The Attempt at a Solution



I know that

ε=6.0 V
VT=5.0 V
and a resistor= 2.0 Ω

The resistor part is what I don't understand. If I'm looking for the internal resistance, I'm looking for the resistance of the resistor. So if they give me the resistance to be 2.0 Ω in the question, shouldn't the answer be 2.0?

The answer is a) 0.40 Ω.
 

Answers and Replies

  • #2
gneill
Mentor
20,816
2,792
1. A battery whose emf is 6.0 V is connected to a 2.0 Ω resistor. The voltage drop across the 2.0 Ω resistor is 5.0 V. What is its internal resistance?

a) 0.40 Ω
b) 1.7 Ω
c) 2.4 Ω
d) 2.5 Ω



Homework Equations



VT=ε-Ir

The Attempt at a Solution



I know that

ε=6.0 V
VT=5.0 V
and a resistor= 2.0 Ω

The resistor part is what I don't understand. If I'm looking for the internal resistance, I'm looking for the resistance of the resistor. So if they give me the resistance to be 2.0 Ω in the question, shouldn't the answer be 2.0?

The answer is a) 0.40 Ω.
You're looking for the internal resistance of the battery.
 

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