20.2 Ohm’s Law: Resistance and Simple Circuits

Where V = IR comes from, what makes a material ohmic, and solving a single-loop circuit for voltage, current, or resistance.

College Physics 2e, 20.2 Ohm’s Law: Resistance and Simple Circuits

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5 exercises

20.2 Exercise 1

If the voltage across a fixed resistance is doubled, what happens to the current?

It doubles.
It halves.
It stays the same.
The current cannot be determined.

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20.2 Exercise 3

What is the resistance of a bulb if the current in it is 1.25 A when a 4 V voltage supply is connected to it? If the voltage supply is increased to 7 V, what will be the current in the bulb?

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20.2 Exercise 6

What current flows through the bulb of a 3.00-V flashlight when its hot resistance is $3 . \text{60 }\Omega$ ?

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20.2 Exercise 8

What is the effective resistance of a car’s starter motor when 150 A flows through it as the car battery applies 11.0 V to the motor?

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20.2 Exercise 10

(a) Find the voltage drop in an extension cord having a $0 . \text{0600}- \Omega$ resistance and through which 5.00 A is flowing. (b) A cheaper cord utilizes thinner wire and has a resistance of $0 . \text{300} \Omega$ . What is the voltage drop in it when 5.00 A flows? (c) Why is the voltage to whatever appliance is being used reduced by this amount? What is the effect on the appliance?

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