Physics Class: Current and Voltage Basics

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Questions and Answers

What type of transistor is designed to amplify current?

Phototransistor

LDR

Thermistor

NPN and PNP (correct)

Which meter is specifically used to measure resistance?

Oscilloscope

Ammeter

Ohmmeter (correct)

Voltmeter

What does an oscilloscope primarily display?

Current flow

Voltage levels only

Resistance properties

The shape of electrical signals over time (correct)

What is the main function of a phototransistor?

To convert light into an electrical signal Signup and view all the answers

Which of the following statements about LDRs is true?

They convert light brightness to resistance. Signup and view all the answers

How much current is considered potentially lethal?

100 milliamps Signup and view all the answers

What is the main purpose of a galvanometer?

To measure tiny currents Signup and view all the answers

What component measures voltage, often referred to as potential difference?

Voltmeter Signup and view all the answers

What is the correct unit for measuring current?

Amperes Signup and view all the answers

Which of the following statements about voltage is true?

Voltage is the energy per unit charge. Signup and view all the answers

How is current typically measured in a circuit?

With an ammeter connected in series Signup and view all the answers

What distinguishes a battery from a single cell?

A battery is made of more than one cell. Signup and view all the answers

Which symbol is correctly used to represent voltage in equations?

V Signup and view all the answers

What does the 'blob' signify in wire connection symbols?

A joint or connection between wires Signup and view all the answers

What is true about direct current (DC)?

It always flows in one direction. Signup and view all the answers

What happens if wires cross in a circuit diagram without a joining 'blob'?

They are always unconnected. Signup and view all the answers

What is the primary function of a fuse in an electrical circuit?

To melt and interrupt the circuit when the current exceeds a limit Signup and view all the answers

In a transformer, how is energy transferred between the two coils?

Via a magnetic field in the core linking the coils Signup and view all the answers

What type of device is a lamp used for lighting in electrical circuits?

A transducer that converts electrical energy to light Signup and view all the answers

Which type of switch allows current to flow only when the button is pressed?

Push-to-make switch Signup and view all the answers

What is a characteristic of a DPST switch?

It isolates both the live and neutral connections. Signup and view all the answers

Which of the following options describes the function of an inductor?

It creates a magnetic field when current passes through it. Signup and view all the answers

What does SPDT stand for in switch terminology?

Single Pole, Double Throw Signup and view all the answers

What is the primary purpose of an earth (ground) connection in electrical circuits?

It provides a pathway for electrical current to escape safely. Signup and view all the answers

What size drill bits are typically used with a portable electric drill?

From 1/6" to approximately 1/4" Signup and view all the answers

What type of file is also known as a rat-tail file?

Round File Signup and view all the answers

Which file is primarily used for enlarging round holes?

Round File Signup and view all the answers

What is a common use for a utility knife?

Cutting various materials for trades and crafts Signup and view all the answers

Which type of saw is specifically designed for cutting metals?

Hacksaw Signup and view all the answers

Which file type is characterized as tapered in width and thickness?

Half Round File Signup and view all the answers

What is the function of the pointed tang at one end of metal files?

To attach a handle Signup and view all the answers

What distinguishes a flat file from a round file?

Shape and application Signup and view all the answers

What is the primary function of a magnifying glass?

To produce a magnified image of an object. Signup and view all the answers

Which of the following statements accurately describes a volt-ohm-milliammeter?

It combines the functions of a voltmeter, ohmmeter, and milliammeter. Signup and view all the answers

What is an oscilloscope primarily used for?

To view signal voltages as a graph. Signup and view all the answers

What is a characteristic feature of hand-held hacksaws?

They consist of a metal arch with a handle around a narrow blade. Signup and view all the answers

Which of the following describes the purpose of a signal generator?

To produce simple wave forms. Signup and view all the answers

Who is credited as the inventor of the magnifying glass?

Roger Bacon Signup and view all the answers

What does a paint brush primarily serve?

For cleaning dirty parts and painting. Signup and view all the answers

What type of instrument measures resistance, as well as voltages?

Volt-ohm-milliammeter Signup and view all the answers

Study Notes

Current and Voltage

Current is the rate of flow of charge.
Voltage is the energy per unit charge.
Current is measured in amperes (A), voltage is measured in volts (V).
Current is represented by the symbol I, voltage is represented by the symbol V.
Current flows into and out of a component.
Voltage is supplied by a battery or power supply.

Schematic Symbols and Their Functions

Wires connect components and pass current easily.
'Blobs' represent where wires are connected.
Cells and batteries supply electrical energy.
A cell is often called a battery, but a battery consists of two or more cells.
DC is the flow of electric current in one direction only.
AC continually changes direction.
Fuses are safety devices that melt if the current flow exceeds a specified value.
Transformers use magnetic fields to step up or step down AC voltages.
Earth (ground) provides a connection to the earth.
Lamps convert electrical energy into light.
Motors convert electrical energy into kinetic (motion) energy.
Buzzers convert electrical energy into sound.
Inductors/coils create a magnetic field when current passes through them.

Switch Symbol Types

Push-to-make switch allows current to flow only when pressed.
Push-to-break switch is normally closed (on) and only opens (off) when pressed.
SPST (Single Pole, Single Throw) switch allows current to flow when closed.
SPDT (Single Pole, Double Throw) switch directs current to one of two routes based on its position.
DPST (Double Pole, Single Throw) switch isolates live and neutral connections.
DPDT (Double Pole, Double Throw) switch is a dual on-off switch.

Transistors

Transistors amplify current and are used in amplifiers and switching circuits.
NPN and PNP transistors are the two common types.
Phototransistors are light-sensitive transistors.

Meters and Oscilloscope

Voltmeters measure voltage (potential difference).
Ammeters measure current.
Galvanometers are highly sensitive meters that measure tiny currents.
Ohmmeters measure resistance.
Oscilloscopes are used to display the shape of electrical signals, and measure voltage and time periods.

Sensors (Input Devices)

Light Dependent Resistor (LDR) converts brightness into resistance.
Thermistors convert temperature into resistance.

Lab Safety

Human fatality can occur with electric currents exceeding 100 milliamps (0.1 amps).

Portable Electric Drill

Used for drilling holes in plastic or metal chassis.

Metal Files

Hand tools with sharp ridges or teeth used for various tasks.
Flat files are used for flat surfaces and edges.
Round files are used for enlarging round holes.
Half Round files are tapered for filing inside rings.

Cutting Tools

Utility knives are used for various cutting tasks.
Hacksaws are used for cutting metals.

Auxiliary Tools

Magnifying glasses are used to magnify objects.
Paint brushes are used for cleaning and painting.

Electronic Equipment

Volt-Ohm-Milliammeter (Multimeter): measures voltage, resistance, and current.
Oscilloscope: displays signal voltages.
Signal Generator: produces simple waveforms.

Studying That Suits You

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Description

Explore the fundamentals of current and voltage in this quiz tailored for physics class. Understand key concepts such as the measurement of current and voltage, and their roles in electrical circuits. Test your knowledge of schematic symbols and their functions in representing electrical components.