Q: A car speaker is rated for a maximum power of 100 W and has a resistance of 4 $$\Omega. $$What is the maximum possible potential difference the amplifier can supply to the speaker?

$$\sqrt{100 \times 4} = 20\ \mathrm{V}$$

Q: A leaf of a corn plant is modeled as a rectangular slab with length $$L = 0.20\ \mathrm{m}$$, width $$w = 0.050\ \mathrm{m}$$, and thickness $$t = 0.25 \times 10$$^{-3}$$\ \mathrm{m}. If $$its resistance is $$130\ \Omega$$, what is its resistivity $$\rho$$?

$$\rho = \dfrac{R A}{L}$$, where $$A = w \times t$$

Question 1

Which physical principle ensures that the total current entering a junction in a circuit equals the total current leaving the junction?

Accepted Answer

Conservation of charge

Question 2

A battery supplies a constant potential difference $$V$$ across a resistor $$R. $$What is the current $$I$$ through the resistor according to Ohm's Law?

Accepted Answer

$$I = \dfrac{V}{R}$$

Question 3

Which of the following statements about the direction of conventional current is correct?

Accepted Answer

It is defined as the flow of positive charge from higher to lower potential.

Question 4

A wire has a length $$L$$, cross-sectional area $$A$$, and resistivity $$\rho. $$What is the resistance $$R of $$the wire?

Accepted Answer

$$R = \dfrac{\rho L}{A}$$

Question 5

If a 1.5 V battery is connected to a 15 $$\Omega$$ resistor, what is the current in the circuit?

Accepted Answer

$$0.10\ \mathrm{A}$$

Question 6

Which material property describes how well a material conducts electric current?

Accepted Answer

Conductivity

Question 7

A flashlight uses two AA batteries (total voltage 3.0 V) and draws a current of 0.40 A. How much electrical energy is consumed in 5 minutes?

Accepted Answer

$$360\ \mathrm{J}$$

Question 8

Which of the following is true about the electric field inside a resistor carrying current?

Accepted Answer

It is uniform and points from high to low potential.

Question 9

A car speaker is rated for a maximum power of 100 W and has a resistance of 4 $$\Omega. $$What is the maximum possible potential difference the amplifier can supply to the speaker?

Accepted Answer

$$\sqrt{100 	imes 4} = 20\ \mathrm{V}$$

Question 10

Which device is designed to have a specific resistance and is used to control current in a circuit?

Accepted Answer

Resistor

Question 11

If the resistance of a wire increases with temperature, what happens to the current for a fixed potential difference?

Accepted Answer

Current decreases

Question 12

Which of the following is NOT an ohmic device?

Accepted Answer

Battery

Question 13

The SI unit of conductance is:

Accepted Answer

Siemens (S)

Question 14

A wire has a resistance $$R. If $$its length is doubled and its cross-sectional area is halved, what happens to its resistance?

Accepted Answer

It becomes $$4R$$

Question 15

Which of the following best describes the energy transformation in a simple circuit with a battery and a resistor?

Accepted Answer

Chemical energy is converted to electrical potential energy and then to thermal energy

Question 16

A battery supplies a current $$I$$ through a resistor $$R. $$What is the power $$P$$ dissipated by the resistor?

Accepted Answer

$$P = I^2$ R$$

Question 17

Which of the following statements about ideal wires in a circuit is correct?

Accepted Answer

Ideal wires have zero resistance and no potential drop across them.

Question 18

In a biological context, which property is often measured to assess tissue composition such as fat versus muscle?

Accepted Answer

Resistance

Question 19

A leaf of a corn plant is modeled as a rectangular slab with length $$L = 0.20\ \mathrm{m}$$, width $$w = 0.050\ \mathrm{m}$$, and thickness $$t = 0.25 	imes 10$$^{-3}$$\ \mathrm{m}. If $$its resistance is $$130\ \Omega$$, what is its resistivity $$ho$$?

Accepted Answer

$$ho = \dfrac{R A}{L}$$, where $$A = w 	imes t$$

Question 20

Which of the following is true about the relationship between resistance $$R$$ and conductance $$G$$?

Accepted Answer

$$G = \dfrac{1}{R}$$

Chapter 22: Current and Resistance – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards