SI Units and Wave Terminology

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Questions and Answers

What is the correct formula for wave speed?

v = λ / f

v = f + λ

v = T / f

v = f × λ (correct)

How is frequency defined in the context of waves?

The time taken for one complete oscillation

The distance between two consecutive crests

The maximum displacement from rest position

The number of oscillations per second (correct)

What characterizes transverse waves?

They can travel through a vacuum without a medium

They consist of oscillations that are not repetitive

Particle motion is parallel to energy propagation

They have particles moving perpendicular to energy propagation (correct)

What is the relationship between time period and frequency?

T = 1 / f Signup and view all the answers

What phenomenon occurs when a wave changes direction upon entering a different medium?

Refraction Signup and view all the answers

Which of the following accurately describes the medium in wave propagation?

The material through which a wave travels Signup and view all the answers

What is the primary cause of sound production?

Vibrating objects Signup and view all the answers

What range of frequencies can humans typically hear?

20 Hz to 20,000 Hz Signup and view all the answers

What does the horizontal axis (X-axis) on a CRO display represent?

Time in milliseconds or microseconds per division Signup and view all the answers

How does a higher time base setting affect the CRO display?

It shows faster signals with smaller values in milliseconds per division Signup and view all the answers

How is the amplitude of a waveform determined on a CRO?

By multiplying the number of vertical divisions by the gain Signup and view all the answers

What is the formula used to calculate frequency from the time period?

Frequency (f) = 1 / Time Period (T) Signup and view all the answers

When observing a waveform on a CRO, how can you determine the time period?

Count the horizontal divisions between two consecutive peaks Signup and view all the answers

What does adjusting the 'Volts/Div' knob do on a CRO?

It compresses or stretches the waveform vertically Signup and view all the answers

What does diffraction refer to in wave behavior?

Waves spreading around objects or through gaps Signup and view all the answers

What is the purpose of the trigger function on a CRO?

To stabilize the waveform display on the screen Signup and view all the answers

How can wavelength be determined from a waveform on a CRO?

By counting horizontal divisions between two consecutive crests and multiplying by the time base Signup and view all the answers

How is the cursor function beneficial on modern oscilloscopes?

It allows calculation of time period and amplitude directly on-screen Signup and view all the answers

What information can be derived from the amplitude of a waveform?

It represents the maximum voltage reached by the signal Signup and view all the answers

If the time period of a signal is measured as 5 ms, what is the frequency?

200 Hz Signup and view all the answers

If a wave spans 4 divisions on the Y-axis at a gain of 0.5 V/div, what is the amplitude?

8 V Signup and view all the answers

Which of the following steps is NOT involved in reading a signal on the CRO?

Changing the frequency of the signal Signup and view all the answers

What is the expected behavior of waves passing through a large aperture?

Waves pass straight through with minimal spreading Signup and view all the answers

How do small apertures affect wave diffraction?

They lead to significant spreading and bending of waves Signup and view all the answers

Which situation depicts low levels of diffraction?

Large wavelength passing through a large aperture Signup and view all the answers

What is the effect of large wavelengths on diffraction when using a small aperture?

They cause increased levels of diffraction Signup and view all the answers

Which statement best summarizes the relationship between aperture size and wavelength in diffraction?

Smaller apertures or longer wavelengths result in increased diffraction Signup and view all the answers

Study Notes

SI Units

Hertz (Hz) is the unit for frequency (cycles per second)
Meters (m) is the unit for distance (wavelength)
Seconds (s) is the unit for time
Meters per second (m/s) is the unit for speed (wave speed)

Terminology and Definitions

Oscillations are repeated back-and-forth motions.
Vibrations are rapid particle movements within a medium.
Frequency is the number of oscillations per second, measured in Hertz (Hz).
Wavelength is the distance between consecutive crests or troughs.
Speed is the rate of wave travel, measured in meters per second (m/s).
Energy propagation is the movement of energy through a medium as waves.
Medium is the material that a wave travels through (e.g., air, water).
Amplitude is the maximum displacement from rest position (related to wave height).
Time period is the time for one complete oscillation, measured in seconds.

Transverse Waves

Particle motion is perpendicular to energy propagation (up and down motion).
Examples include light waves, water waves, and waves on a string.

Longitudinal Waves

Particle motion is parallel to energy propagation (back and forth motion).
Examples include sound waves, shock waves, and pressure waves.

Wave Equation

Wave speed (v) equals frequency (f) multiplied by wavelength (λ).
Formula: v = f × λ

Time Period/Frequency

Time period (T) is the time for one oscillation.
- Formula: T = 1 / f
Frequency (f) is the number of oscillations per second.
- Formula: f = 1 / T

Wave Behaviour

Reflection is when a wave bounces off a surface.
Refraction is when a wave changes direction passing from one medium to another (due to a change in speed).
Diffraction is when waves spread out passing through a gap or around obstacles.
Diffraction is more pronounced with smaller apertures and larger wavelengths.

Sound

Sound is produced by vibrating objects and needs a medium to transmit.
Sound speed is calculated as speed = distance/time.
A practical technique involves using two microphones to measure sound velocity.
The human hearing range is approximately 20 Hz to 20,000 Hz.
Noise is unwanted or unpleasant sound.

Cathode Ray Oscilloscope (CRO)

CROs are used to measure time period (one complete oscillation) by using the time base setting.
Frequency can be calculated using f = 1 / T.
CROs can display waveforms of various sound sources, including musical instruments.

Types of Waves in a Ripple Tank

Reflection, refraction, and diffraction behaviours are observed similar to other wave types.

Reading a CRO

Understanding the Display

The CRO displays waveforms with:
- Horizontal axis (X-axis): representing time (ms or μs per division)
- Vertical axis (Y-axis): representing voltage (V or mV per division)

Adjusting Controls

Time base (X-axis): Adjust the rate at which the signal moves, affecting the scale (higher/smaller values for higher signals, lower/larger for slow signals)
Voltage (Y-axis): Adjusts to vertically compress/stretch the waveform according to the voltage scale.

Reading the Signal

Frequency: Measured by the time period (T) for one cycle, using the formula f= 1/T
Amplitude: Measured from the baseline to the peak or trough of the wave.
Wavelength: Found by counting the horizontal divisions between crests and multiplying by the time base setting.

Cursor Function

Modern oscilloscopes feature a cursor function allowing for direct measurement of time periods and amplitudes.

Triggering

Crucial for stable waveform display by synchronizing the waveform.

Determining Values

Amplitude

Step 1: Observe the vertical scale markings (mV/div or V/div).
Step 2: Count the vertical divisions from baseline to peak.
Step 3: Multiply the number of divisions by the gain to get amplitude.

Time Period

Step 1: Observe the horizontal scale markings (ms/div or s/div).
Step 2: Count the horizontal divisions for one complete cycle.
Step 3: Multiply the number of divisions by the time base to get time period.

Frequency

Use the formula: f = 1 / T

Formulas Summary

Amplitude = Number of divisions × Gain
Time Period (T) = Number of divisions × Time Base
Frequency (f) = 1 / Time Period (T)

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Description

Test your knowledge on SI units related to waves, their terminology, and the definitions of key concepts such as frequency, wavelength, and speed. This quiz covers essential terms and principles related to oscillations and energy propagation in various mediums.