Introduction to Electricity & Electric Current

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Questions and Answers

In a simple electrical circuit consisting of a battery, switch, and lamp, what is the conventional direction of current flow, and why was this concept developed?

From negative to positive; to align with the actual movement of electrons in modern circuits.
From positive to negative; to simplify calculations involving electron charge and flow.
From positive to negative; based on Benjamin Franklin's theory of electric fluid. (correct)
From negative to positive; based on Joseph Thompson's discovery of electron flow.

How does a battery facilitate the flow of electric current in a circuit, and what unit is used to measure its 'pushing' force?

By acting as a pump, providing pressure; measured in volts (V). (correct)
By creating resistance; measured in ohms.
By generating electrons; measured in amperes (amps).
By converting electrical energy to mechanical energy; measured in watts.

If a copper wire carries a current of 2 amps, approximately how many electrons are flowing past a given point in the wire each second?

12.4 quintillion electrons. (correct)
3.1 quintillion electrons.
6.2 quintillion electrons.
1.6 quintillion electrons.

In the context of electrical current in a copper wire, what causes a copper atom to become a positive ion, and how does this relate to electron flow?

Losing an electron due to thermal energy; contributes to electrical conductivity. (B) Signup and view all the answers

How does the direction of electric field lines differ between protons and electrons, and what does this indicate about their electric fields?

Protons have field lines pointing outwards, while electrons have them pointing inwards; demonstrating opposite electrical charges. (D) Signup and view all the answers

What role does resistance play in an electrical circuit, and how does it affect the flow of current, according to basic electrical principles?

It limits the amount of current flowing in the circuit; similar to a narrow pipe restricting water flow. (D) Signup and view all the answers

Given a circuit with a 9V battery and a resistance of 3 ohms, what is the current flowing through the circuit, and which law allows you to calculate this?

3 amps; calculated using Ohm's Law. (A) Signup and view all the answers

Why do mobile electrons in a copper wire move randomly in all directions when no electric field is applied, and what is the average net movement of these electrons?

Due to thermal energy causing chaotic motion; resulting in an average movement of zero. (B) Signup and view all the answers

What is the primary role of surface charges in an electrical circuit?

To establish an electric field that drives electron drift. (B) Signup and view all the answers

In a circuit with a resistive wire connected to a 10-volt battery, what happens to the voltage and current along the length of the wire?

Voltage gradually decreases, while current remains the same. (C) Signup and view all the answers

Why does a lamp filament heat up and emit light when electrons flow through it?

Accelerated electrons collide with atoms in the filament, transferring kinetic energy and causing heat and light. (C) Signup and view all the answers

How does closing a switch initiate the flow of current in a circuit containing a lamp?

It initiates complex interactions that establish a gradient of surface charges and electric fields, leading to electron flow. (C) Signup and view all the answers

What determines the strength of the electric field within the lamp filament compared to the connecting wires?

A steeper surface charge gradient exists in the filament due to its higher resistance. (C) Signup and view all the answers

If drift speed is so slow (less than 0.1 mm/s at 1 amp), why does a light bulb appear to turn on almost instantly when a switch is flipped?

The electric and magnetic fields propagate the influence of electron movement, doing so at close to the speed of light. (A) Signup and view all the answers

What occurs when the charges along the face of a switch meet as it closes?

They meet and cancel out. (C) Signup and view all the answers

What is the role of the chemical reaction within a battery in maintaining an electric circuit?

The chemical reactions absorb electrons on one side and eject electrons on the other, creating an electric field. (D) Signup and view all the answers

How do electric and magnetic fields contribute to stabilizing a circuit after a switch is closed?

They interact and help establish the gradient of surface charges and electric fields, stabilizing the circuit. (B) Signup and view all the answers

What is the effect of reducing the cross-sectional area of a conductive material on the flow speed of electrons?

Increases the flow speed. (D) Signup and view all the answers

Flashcards

Simple Electric Circuit

A complete path for current to flow, including a power source, switch, load (like a lamp), and connecting wires.

Conventional Current

The flow of positive charge from a positive terminal to a negative terminal (historical perspective).