Physics: Waves and Radiation

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Questions and Answers

What happens to the speed of a wave when it enters a denser medium?

It increases.

It doubles.

It decreases. (correct)

It remains unchanged.

Which statement is true regarding the law of reflection?

The angle of reflection varies with wavelength.

The angle of incidence is equal to the angle of reflection. (correct)

The angle of incidence is always greater than the angle of reflection.

The angle of reflection is always zero.

Which electromagnetic wave is used for satellite transmissions and cooking?

X-rays

Ultraviolet light

Gamma rays

Microwaves (correct)

What effect does ultraviolet light exposure have on human health?

Increases the risk of skin cancer. Signup and view all the answers

What is true about the frequency of a wave when it is refracted?

It remains the same. Signup and view all the answers

Which color is not part of the visible spectrum?

Ultraviolet Signup and view all the answers

Which electromagnetic wave is known for its application in medical imaging?

X-rays Signup and view all the answers

What is the correct order of the electromagnetic spectrum from longest wavelength to shortest?

Radio waves, Microwaves, Infrared, Visible light, Ultraviolet, X-rays, Gamma rays Signup and view all the answers

What type of wave consists of compressions and rarefactions?

Longitudinal wave Signup and view all the answers

Which parameter measures the distance from the equilibrium position to the maximum displacement in a wave?

Amplitude Signup and view all the answers

How is the speed of a wave calculated?

Frequency × Wavelength Signup and view all the answers

Which of the following describes the Doppler effect?

Change in observed frequency and wavelength due to motion Signup and view all the answers

What is the relationship between frequency and time period?

Frequency is the reciprocal of time period Signup and view all the answers

In terms of waves, what is frequency defined as?

Number of waves that pass a point per second Signup and view all the answers

What kind of wave has vibrations that occur at right angles to the direction of travel?

Transverse wave Signup and view all the answers

What happens to wavefronts if the wave source is moving towards an observer?

They become bunched together Signup and view all the answers

What is the primary reason for using protective shielding made of dense materials like lead when working with X-rays and Gamma rays?

To protect against ionising radiation that can cause mutations Signup and view all the answers

Which statement accurately describes the behavior of light when it passes from a less optically dense medium to a more optically dense medium?

The angle of refraction is less than the angle of incidence. Signup and view all the answers

What phenomenon occurs when light travels along the boundary of two different media at a specific critical angle?

Total internal reflection Signup and view all the answers

Which equation relates the angle of incidence and angle of refraction to the refractive index of a medium?

n1sin(i) = n2sin(r) Signup and view all the answers

What is the critical angle in the context of total internal reflection?

The angle of incidence where light will reflect back into the original medium Signup and view all the answers

What role does optical fibre play in the transmission of information?

It employs total internal reflection to carry light signals. Signup and view all the answers

What happens to light when it passes through a glass slab at an angle to its normal?

It bends towards the normal when entering the slab. Signup and view all the answers

Why is reflection demonstrated in a ray diagram with a plane mirror?

To represent the formation of an image through reflection Signup and view all the answers

What is the relationship between amplitude and loudness in sound waves?

Greater amplitude results in greater loudness. Signup and view all the answers

How can the speed of sound in air be measured?

By timing how long a sound takes to echo back from a wall. Signup and view all the answers

What occurs to sound waves during refraction?

They bend as they pass through different mediums. Signup and view all the answers

Which frequencies fall within the audible range for a healthy human ear?

20 Hz to 20000 Hz Signup and view all the answers

What characterizes the first sound wave described?

Quiet and low-pitched Signup and view all the answers

Study Notes

Ionising Radiation

X-rays and Gamma rays are types of ionising radiation that can lead to mutations and cancer.
Minimizing exposure is crucial; protective shielding should use dense materials like lead.

Light and Sound Waves

Light waves are transverse, characterized by peaks and troughs, and they vibrate at right angles to their direction of travel.
Sound waves are longitudinal, featuring compressions and rarefactions, with vibrations in the direction of travel.

Reflection and Refraction

Reflection occurs when light bounces off a surface, such as a plane mirror, and can be illustrated through ray diagrams.
Refraction happens when light passes through different media, altering its angle; denser media slow down light leading to bending towards the normal.
Snell's law: n1 * sin(i) = n2 * sin(r), where n represents refractive index, i is the angle of incidence, and r is the angle of refraction.

Total Internal Reflection

Occurs at the critical angle; when light hits a boundary at an angle greater than the critical angle, it reflects back into the denser medium, common from glass to air.
The critical angle is defined by n = 1/sin(c) where n is the refractive index and c is the critical angle.

Optical Fibres

Composed of glass with cladding, optical fibres use total internal reflection to transmit information via light, maintaining performance even when bent.

General Wave Properties

Waves transfer energy without transferring matter; particles oscillate around a fixed point.
Key terms: Amplitude (max displacement from equilibrium), Wavefront (points on wave in cycle), Frequency (waves per second), Wavelength (distance between two points), Time period (duration of one wave).

Wave Speed and Relationships

Wave speed equation: v = frequency × wavelength.
Frequency relates to time period: f = 1/T.

The Doppler Effect

A change in observed frequency and wavelength occurs when a wave source moves relative to an observer (e.g., a siren changing pitch when passing).

Electromagnetic Spectrum

Key categories in order: Radio waves, Microwaves, Infrared, Visible light (ROYGBIV), Ultraviolet, X-rays, Gamma rays.
All electromagnetic waves travel at high speeds in a vacuum.

Uses and Hazards of Electromagnetic Waves

Radio waves: Communication (TV/radio), reflected by the ionosphere.
Microwaves: Cooking and satellite transmissions; penetrate materials effectively.
Infrared: Heaters and night vision technology.
Visible Light: Fibre optics and photography.
Ultraviolet: Fluorescent lamps and tanning.
X-rays: Medical imaging and security; can penetrate materials.
Gamma radiation: Food and medical equipment sterilization.
Hazards: Microwaves cause internal heating, infrared leads to burns, ultraviolet raises skin cancer risk.

Sound Wave Properties

Audible range for humans is 20 Hz to 20,000 Hz.
Speed of sound can be measured by timing the echo of a sound made at a distance from a wall: speed = distance/time.
An oscilloscope connected to a microphone can display sound waves, showing frequency and amplitude relationship: greater amplitude = louder sound, greater frequency = higher pitch.

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Description

This quiz covers key concepts in physics related to ionising radiation, light, and sound waves. You'll explore phenomena such as reflection, refraction, and total internal reflection along with their applications. Test your understanding of these fundamental physical principles and their implications.