National 4 & 5 Physics Portree High School
Waves & Radiation 2 – Homework 1
1. (i)
Calculate the wavelength in air of a sound signal of frequency 800Hz.
(ii)
The same sound signal is now passed through a solid in which it travels at 1200ms-1.
Calculate the wavelength of the signal in the soild.
2. Which of these waves has (a) the highest frequency, (b) the lowest amplitude?
3. (a)
Calculate the wavelength of the following wave:
(b)
5 of these waves pass a point in 0.1 s, calculate the frequency.
(c)
Calculate the speed of the wave.
(d)
Using you answer to part (c) above, how long would it take a crest on the wave to
travel 2400m?
4.
Light can be considered as a wave. Your task in this question is to carry out some web
research and identify appropriate wavelengths for the following colours of light:
(a) Red
(b) Green
(c) Blue
National 4 & 5 Physics Portree High School
Waves and Radiation 2 – Homework 2
1. What is diffraction? Use a diagram to show which wavelengths diffract most.
2. Give examples of diffraction in nature.
3. What happens to white light when it is passed through a diffraction grating?
4. Describe a simple experiment to measure the wavelength of green light using a diffraction
grating.
5. Describe one other use of diffraction not covered so far in this homework sheet.
National 4 & 5 Physics Portree High School
Waves and Radiation 2 – Homework 3
1. What do all members of the Electromagnetic Spectrum have in common?
2. Put these radiations in order of largest wavelength first:
Visible light, x-rays, radio waves, UV, gamma rays, microwaves, infra red
3. State two forms of radiation in the EM spectrum and describe one medical use and
one non medical use for each radiation.
4. (a)
(b)
What are the hazards associated with UV?
What are the precautions to be taken to limit these hazards?
5.
What does the energy of each type of radiation in the EM spectrum depend on?
6.
Calculate the energy in a photon of UV radiation of frequency 3 x 1016Hz.
( h = 6.63 x 10-34JS)
National 4 & 5 Physics Portree High School
Waves and Radiation 2 – Homework 4
1. Using a diagram, describe what is meant by ‘ionisation’.
2. Why is ionisation bad in living tissue?
3. Name four sources of background radiation.
4. What is meant by the ‘Activity’ of a radioactive source?
5. Calculate the activity of a source if 300 decays occur in 0.2 s.
National 4 & 5 Physics Portree High School
Waves and Radiation 2 – Homework 5
1. The Activity of a radioactive source is 8000Bq. What does ‘Bq’ stand for?
2. For the source described in q 1 above, calculate how many decays there are in 3
minutes. (Write your answer in Scientific Notation).
3. What is the activity of a source if 4800 decays occur in 2 minutes?
4. How long would it take a source of activity 9600 Bq to produce 7.68 x 10 4 decays?
5. Carry out some web research and write a short paragraph on ‘Marie Curie’.
National 4 & 5 Physics Portree High School
Waves and Radiation 2 – Homework 6
1. Describe some advantages and disadvantages of electricity generation using nuclear
power.
2. Describe two other applications for ionising radiation.
3. Identify the type of radiation described by the following statements:
(a) I’m a small particle and can travel 30cm in air.
(b) I’m a large heavy particle and paper stops me.
(c) I just keep going and going until I’m stopped by lead or concrete.
4. What is equivalent dose and what is it measured in?
5. What is meant by the ‘half life’ of a radioactive sample?
6. Calculate the half life of a radioactive sample if it takes 48 days for the activity to fall
from 960Bq to 15Bq.
National 4 & 5 Physics Portree High School
Waves and Radiation 2 – Homework 7
1. An experiment to determine the half life of a radioactive source was carried out. Before the
experiment was started, the background count rate was measured and was found to be
15Bq.
Results of the experiment as follows:
Time (s)
0
5
10
15
20
25
30
Activity (Bq)
115
75
65
45
40
38
37
Your first task is to adjust these reading to take account of the background count rate. When you’ve
done that, construct a graph of adjusted activity against time. Use the proper graph paper
provided. The diagram below tells you what to put on each axis.
Use the graph you have made to determine the half life of the substance.
National 4 & 5 Physics Portree High School
Waves and Radiation 2 – Homework 8
1. A radioactive sample has a half life of 2 s. What fraction of the activity is left after
10s has elapsed?
2. A school receives a radioactive sample at 10am with an activity of 2.4KBq. Due to
health & safety, the sample cannot be used in the classroom until the activity is 150
Bq. Calculate the earliest time that the sample can be safely used in the classroom.
3. State the difference between fission and fusion.
4. When studying a fission reaction, a scientist measures that there is 2.8 x 10 -30Kg of
matter less before the reaction compared with after. Do some web research and
identify:
(a) Where has this lost mass gone?
(b) Which famous equation can be used to calculate the energy released as a result
of the loss in mass?
5. With the aid of a diagram describe what is meant by a ‘chain reaction’.