Q: If two resistors $$R_1$$ and $$R_2$$ are connected in parallel, what is the equivalent resistance $$R_{\text{eq}}$$?

$$\dfrac{1}{R_{\text{eq}}} = \dfrac{1}{R_1$} + \dfrac{1}{R_2$}$$

Q: In a parallel circuit with two resistors, $$R_1 = 2$$\ \Omega$$ and R_2$ = 3\ \Omega$$, what is the equivalent resistance?

$$R_{\text{eq}} = 1.2\ \Omega$$

Question 1

A fluorescent light bulb emits visible light by converting ultraviolet radiation. What is the primary process that generates the ultraviolet radiation inside the bulb?

Accepted Answer

Mercury atoms emit ultraviolet radiation when excited by an electric current.

Question 2

Which analogy best describes the role of a battery in an electric circuit, based on the water flow model?

Accepted Answer

The battery is like the pump.

Question 3

If 6 C of charge pass through a wire in 3 seconds, what is the electric current $$I$$?

Accepted Answer

$$I = 2\ \mathrm{A}$$

Question 4

Which statement about conventional current and electron current is correct?

Accepted Answer

Conventional current is defined as the flow of positive charges.

Question 5

What does a light bulb 'use up' when it is part of a closed electric circuit?

Accepted Answer

It uses up the chemical energy stored in the battery.

Question 6

According to Kirchhoff's Current Law (Current Node Rule), what must be true at any node in a circuit?

Accepted Answer

The sum of the currents entering the node equals the sum leaving.

Question 7

A resistor has a length $$L$$, cross-sectional area $$A$$, and is made of material with resistivity $$\rho. $$What is its resistance $$R$$?

Accepted Answer

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

Question 8

In a simple circuit with a battery and a single resistor, what is the current $$I if $$the battery voltage is $$V$$ and the resistance is $$R$$?

Accepted Answer

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

Question 9

Two resistors $$R_1$$ and $$R_2$$ are connected in series to a battery of voltage $$V. $$What is the current $$I$$ through the circuit?

Accepted Answer

$$I = \dfrac{V}{R_1$ + R_2$}$$

Question 10

If two resistors $$R_1$$ and $$R_2$$ are connected in parallel, what is the equivalent resistance $$R_{	ext{eq}}$$?

Accepted Answer

$$\dfrac{1}{R_{	ext{eq}}} = \dfrac{1}{R_1$} + \dfrac{1}{R_2$}$$

Question 11

A battery is described as having an electromotive force (EMF) $$\mathcal{E}. $$What does this EMF represent?

Accepted Answer

The potential difference the battery creates between its terminals.

Question 12

In a circuit diagram, what does a closed switch represent?

Accepted Answer

A connection with zero resistance, just like a wire.

Question 13

If a wire has zero resistance, what is the potential difference across any two points on the wire?

Accepted Answer

It is always zero.

Question 14

A circuit contains a battery, a switch, and a light bulb. When the switch is closed, the bulb lights up. What happens to the current if the resistance of the bulb increases while the battery voltage stays the same?

Accepted Answer

The current decreases.

Question 15

Which of the following best explains why hair stands on end when a person touches a Van de Graaff generator?

Accepted Answer

The generator charges the person, causing each hair to acquire the same type of charge and repel each other.

Question 16

In a parallel circuit with two resistors, $$R_1 = 2$$\ \Omega$$ and R_2$ = 3\ \Omega$$, what is the equivalent resistance?

Accepted Answer

$$R_{	ext{eq}} = 1.2\ \Omega$$

Question 17

A circuit has a battery of $$12\ \mathrm{V}$$ and two resistors in series: $$R_1 = 2$$\ \Omega$$ and R_2$ = 4\ \Omega. $$What is the current through the circuit?

Accepted Answer

$$I = 2\ \mathrm{A}$$

Question 18

Which of the following is NOT a correct statement about electric current in a metal wire?

Accepted Answer

The direction of conventional current is the same as the direction of electron flow.

Question 19

If a circuit contains a node where 3 A of current enters from one branch and 2 A enters from another, what must be the total current leaving the node?

Accepted Answer

5 A

Electric Current, Circuits, and Resistance: Study Notes

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