# (d) Light and sound

## 3.17 practical: investigate the refraction of light, using rectangular blocks, semi-circular blocks and triangular prisms

 1.       Set up your apparatus as shown in the diagram using a rectangular block. 2.       Shine the light ray through the glass block 3.       Use crosses to mark the path of the ray. 4.       Join up crosses with a ruler 5.       Draw on a normal where the ray enters the glass block 6.       Measure the angle of incidence and the angle of refraction and add these to your results table 7.       Comment on how the speed of the light has changed as the light moves between the mediums. 8.       Repeat this for different angles of incidence and different glass prisms.

## 3.19 practical: investigate the refractive index of glass, using a glass block

 1.       Set up your apparatus as shown in the diagram using a rectangular block. 2.       Shine the light ray through the glass block 3.       Use crosses to mark the path of the ray. 4.       Join up crosses with a ruler 5.       Draw on a normal where the ray enters the glass block 6.       Measure the angle of incidence and the angle of refraction and add these to your results table 7.       Calculate the refractive index 8.       Repeat steps 2 – 7 using a different angle of incidence 9.       Find an average of your results.

## 3.21 explain the meaning of critical angle c

Critical Angle:

• The angle of incidence which produces an angle of refraction of 900 (refracted ray is along the boundary of the surface).
• When the angle of incidence is greater than the critical angle, total internal reflection occurs (all light is reflected at the boundary).
• This effect only occurs at a boundary from a high refractive index material to a low refractive index material.

## 3.26 understand how an oscilloscope and microphone can be used to display a sound wave

 With the microphone plugged into the oscilloscope and a sound incident on the microphone, the microphone will transfer the sound into an electrical signal which the oscilloscope can display .The x axis show the time base which can be adjusted for example 2ms for 1 square so time period and frequency can be calculated from this, along the y axis voltage is displayed as the wave is converted into an electrical signal this means amplitudes can be compared.

## 3.28 understand how the pitch of a sound relates to the frequency of vibration of the source

 High frequency means high pitch. If a string vibrates with a higher frequency then the note sounds higher.

## 3.29 understand how the loudness of a sound relates to the amplitude of vibration of the source

The greater the amplitude the louder the sound. Bigger vibrations of a sting mean more energy is being put in so more energy out as sound waves.

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Section 1: Principles of chemistry

a) States of matter

b) Atoms

c) Atomic structure

d) Relative formula masses and molar volumes of gases

e) Chemical formulae and chemical equations

f) Ionic compounds

g) Covalent substances

h) Metallic crystals

i) Electrolysis

Section 2: Chemistry of the elements

a) The Periodic Table

b) Group 1 elements: lithium, sodium and potassium

c) Group 7 elements: chlorine, bromine and iodine

d) Oxygen and oxides

e) Hydrogen and water

f) Reactivity series

g) Tests for ions and gases

Section 3: Organic chemistry

a) Introduction

b) Alkanes

c) Alkenes

d) Ethanol

Section 4: Physical chemistry

a) Acids, alkalis and salts

b) Energetics

c) Rates of reaction

d) Equilibria

Section 5: Chemistry in industry

a) Extraction and uses of metals

b) Crude oil

c) Synthetic polymers

d) The industrial manufacture of chemicals

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