Q: The resistivity of a material increases with temperature according to $$\rho = \$$rho_0$$ [1 + \alpha (T - T_0$)]. If $$the resistivity of Nichrome at $$20^\circC is$$ $$100 \times 10$$^{-8}$$ \Omega \cdot m$$ and $$\alpha = 4 \times 10$$^{-4}$$ \ ^\circC$^{-1}$$, what is its resistivity at $$520^\circC$$?

$$\rho = 120 \times 10$$^{-8}$$ \Omega \cdot m$$

Q: A resistor has color bands: green, violet, orange, and silver. What is its resistance and tolerance?

$$57 \times 10^3$ \Omega$$ with $$\pm 10\%$$ tolerance

Q: A copper wire carries a current of $$1.67 A $$and has a cross-sectional area of $$8.20 \times 10$$^{-7}$$ m^2$. If the resistivity of copper is 1.72$$ \times $$10^{-8}$$ \Omega \cdot m$$, what is the electric field magnitude in the wire?

$$E = 2.09 \times 10$$^{-2}$$ V/m

Question 1

Which of the following best describes the direction of conventional current in a conductor?

Accepted Answer

It is opposite to the direction of electron drift velocity.

Question 2

A cylindrical copper wire has a cross-sectional area $$A$$, length $$L$$, and carries a current $$I. $$Which equation gives the resistance $$R of $$the wire?

Accepted Answer

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

Question 3

A 22-gauge nichrome wire has a radius of $$0.321 	imes 10$$^{-3}$$ m and a resistivity of 1.5$$ 	imes $$10^{-6}$$ \Omega \cdot m$$. What is the resistance per meter of this wire?

Accepted Answer

$$R = 4.6 \Omega/m$$

Question 4

Which device is always connected in parallel in a circuit and ideally has infinite resistance?

Accepted Answer

Voltmeter

Question 5

A battery with emf $$\mathcal{E}$$ and internal resistance $$r is $$connected to an external resistor $$R. $$What is the current $$I in $$the circuit?

Accepted Answer

$$I = \frac{\mathcal{E}}{R + r}$$

Question 6

Which of the following statements about Ohm’s Law is correct?

Accepted Answer

Ohm’s Law states that $$V = IR$$ for ohmic materials.

Question 7

A 1.3 kW electric frying pan is plugged into a 120 V circuit. What is the current drawn by the frying pan?

Accepted Answer

$$I = 10.8 A$$

Question 8

The resistivity of a material increases with temperature according to $$ho = \$$rho_0$$ [1 + \alpha (T - T_0$)]. If $$the resistivity of Nichrome at $$20^\circC is$$ $$100 	imes 10$$^{-8}$$ \Omega \cdot m$$ and $$\alpha = 4 	imes 10$$^{-4}$$ \ ^\circC$^{-1}$$, what is its resistivity at $$520^\circC$$?

Accepted Answer

$$ho = 120 	imes 10$$^{-8}$$ \Omega \cdot m$$

Question 9

Which of the following best describes a non-ohmic resistor, such as a semiconductor diode?

Accepted Answer

Current increases nonlinearly with voltage in one direction and little current flows in the other.

Question 10

A resistor has color bands: green, violet, orange, and silver. What is its resistance and tolerance?

Accepted Answer

$$57 	imes 10^3$ \Omega$$ with $$\pm 10\%$$ tolerance

Question 11

In a circuit with a battery of emf $$\mathcal{E} = 12 V$$, internal resistance $$r = 2 \Omega$$, and external resistance $$R = 4 \Omega$$, what is the terminal voltage across the battery when the circuit is closed?

Accepted Answer

$$V = 8 V$$

Question 12

Which equation correctly expresses the power dissipated in a resistor $$R$$ with current $$I$$ flowing through it?

Accepted Answer

$$P = I^2$R$$

Question 13

A 100 W lamp is plugged into a 120 V circuit. What is the resistance of the lamp?

Accepted Answer

$$R = 144 \Omega$$

Question 14

Which of the following is true about the household power distribution system?

Accepted Answer

The neutral line is connected to ground.

Question 15

If a voltmeter is connected across a resistor in a circuit, what does it measure?

Accepted Answer

The potential difference across the resistor.

Question 16

A copper wire carries a current of $$1.67 A $$and has a cross-sectional area of $$8.20 	imes 10$$^{-7}$$ m^2$. If the resistivity of copper is 1.72$$ 	imes $$10^{-8}$$ \Omega \cdot m$$, what is the electric field magnitude in the wire?

Accepted Answer

$$E = 2.09 	imes 10$$^{-2}$$ V/m

Question 17

Which of the following statements about internal resistance in batteries is correct?

Accepted Answer

Internal resistance decreases the terminal voltage.

Question 18

A circuit contains a battery with emf $$\mathcal{E}$$, internal resistance $$r$$, and an external resistor $$R. If $$the current is $$I$$, what is the voltage drop across the internal resistance?

Accepted Answer

$$V = Ir$$

Question 19

Which of the following is the correct unit for resistivity?

Accepted Answer

$$\Omega \cdot m$$

Current, Resistance, and Electromotive Force

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