# Waves in Sight and Hearing | Physics Homework Help

YOU MUST DO FOLLOWING POINTS AND ADD THEM LABELLED 1.1 ETC TO EACH RELEVANTANSWER /TEXT

 1.1 Interpret wave types and features. 1.2 Explain amplitude, wavelength, frequency and speed for waves in 1.1. 1.3 Calculate changes in frequency and wavelength. 3.1 Demonstrate the effect of a range of lenses on parallel light.

INSTRUCTIONS

2. You can use a scientific calculator.
3. All multiple-choice questions have ONE correct answer only.

QUESTIONS

1A transverse wave is transporting energy from east to west. The particles of the medium will move

a. east to west only

b. north to south only

c. both northward and southward

1mark(1.1)
2The speed of a wave depends upon (i.e., is causally affected by) …

a. the properties of the medium through which the wave travels

b. the wavelength or frequency of the wave.

c. both the wavelength and the frequency of the wave.

1mark(1.1)
3The time required for the sound waves (v = 338 m/s) to travel from the tuning fork to point A is

 a. 20 ms b. 59 ms c. 0.059 s d. 338 m/s
2marks(1.3)
4Electromagnetic waves travel at a speed of 3.0 x 108 m/s through the air. A radio station transmits using waves with a wavelength of 1.9 x 102 m. At what frequency would you need to set your radio to receive this particular station’s programmes?2marks(1.3)

1. 1578947 m
1. 1.579 MHz

1. 157.9 kHz
1. 15.79 kHz

5

Dawn and Bob have stretched a slinky between them and begin experimenting with waves. As the frequency of the waves is halved,

a. the wavelength remains constant and the speed is doubled

b. both the wavelength and the speed are halved.

c. the wavelength is doubled and the speed remains constant

1mark(1.1)
6Mac and Jon are resting on top of the water near the end of the pool when Mac creates a surface wave. The wave travels the length of the pool and back in 12 s. The pool is 18 m long. Determine the speed of the wave.

F = 1/T     T=12 s

F=1/12

Speed (v) = 8 / (1/12)

Speed = 96 m/s

2marks(1.3)
7Two waves on identical strings have frequencies in a ratio of 2 to 1. If their wave speeds are the same, then how do their wavelengths compare?

 a. 2:1 b. 1:2 c. 4:1                d. 1:4
2marks(1.3)

8

A standing wave is formed when

a. a wave refracts due to changes in the properties of the medium.

b. a wave reflects off a canyon wall and is heard shortly after it is formed.

c. red, orange, and yellow wavelengths bend around suspended atmospheric particles.

d. two identical waves moving different directions along the same medium interfere.

1mark

(1.1)

9The string below is 5.0 m long. The string vibrates up and down with 18 complete cycles in 3 s. Determine the frequency, period, wavelength and speed for this wave.

Frequency –> f = (18 cycles) / (3 seconds) = 6 Hz

Period –> T = 1 / (6 Hz) = 0.167 Seconds

Wavelength –> W = 5 / (2) = 2.5m

Speed – > f x W = 6 x 2.5 = 15m/s

4marks(1.3)
10Consider the standing wave pattern below

a
The number of nodes in the entire pattern is

 a. 7 b. 9 c. 16 d. none of these
2marks1.1
bOf all the labelled points, destructive interference occurs at point(s) ____.

 a. B, C, and D b. A, E, and F c. A only d. C only e. none of these answers
2marks1.1
11aA string which is 1.5 m long vibrates up and down with 8 complete cycles in 5 s. Determine the amplitude, frequency, period, wavelength and speed for this wave.

 12 cm

Amplitude: 6cm or 0.06m

Frequency: 0.1 Hz

Period: 10s

Wavelength: 3.0 m

Speed: 1.5 / 5 = 0.3m/s

5marks(1.3)
BUsing your answers to part a above, explain the terms; amplitude, wavelength, frequency, period and speed for waves

Amplitude: maximum displacement from the equilibrium position of an object oscillating around such equilibrium position

Wavelength: The distance between two identical adjacent points in a wave

Frequency: Number of events per unit of time

Period: Time it takes to complete one oscillation

Speed: Distance traversed by a periodic, or cyclic, motion per unit time

5marks(1.2)

12

A wave is transporting energy from left to right. The particles of the medium are moving back and forth in a leftward and rightward direction. This type of wave is known as a

 a. mechanical b. electromagnetic c. transverse d. longitudinal

2marks

(1.1)

13A transverse wave is observed to be moving along a lengthy rope. Adjacent crests are positioned 3.2 m apart. Exactly 6 crests are observed to move past a given point along the medium in 9 s. Determine the wavelength, frequency, period and speed of these waves.

Wavelength = 3.2 m

Speed = 2.11 m/s

Frequency = 0.66 Hz

4marks(1.1)
14Which of the following best describes the image for a thin diverging lens that forms whenever the magnitude of the object distance is less than that of the lens’ focal length?

 a. inverted, enlarged and real b. upright, enlarged and virtual c. upright, reduced and virtual d. inverted, reduced and real
2marks(3.1

 15 A converging lens of focal length 4 cm being used as a magnifying glass. An object 1.5 cm tall is placed 2.8 cm from the lens. 3marks (3.1) a Use a ruler to construct accurately the position and size of the image. You should show how you construct your ray diagram. b Describe the image.The image is virtual, upright, same side as the object and larger that the object

 16 The diagram shows two parallel rays of light, a lens and its axis. 3marks (3.1) a Complete the diagram to show what happens to the rays. b Name the point where the rays seem to come together.The principal focus OR focal point C What word can be used to describe this type of lens?Convex lens or converging lens

 17 A student investigated how the nature of the image depends on the position of the object in front of a large converging lens. The diagram shows one position for the object. 3marks (3.1) a Use a ruler to complete a ray diagram to show how the image of the object is formed. b Describe the nature of this image relative to the object.The Real image is same distance from the focal point but in the opposite direction. It remains the same size and height but upside down.

 18 The diagram shows an object located vertically on the principal axis of a diverging lens. A student looks through the lens and can see an image of the object. 3marks (3.1) a Use a ruler to complete a ray diagram to show how the image of the object is formed. b Describe the nature of this image relative to the object.

The image formed is Virtual Upright, diminished and closer to the lens than the object