24.2 Production & Use of X-rays | CIE A Level Physics Topic Questions 2025

1a

1 mark

In an X-ray tube, charged particles are accelerated towards a metal target by an applied potential difference.

State the name of the charged particles that are accelerated by the applied potential difference.

How did you do?

1b

10 marks

Fig. 1.1 shows a simplified diagram of an X-ray tube.

24-1-3a-e-24-1-e-structure-of-an-x-ray-tube-cie-ial-sq

Fig. 1.1

State the name and purpose of

(i)

Component A

[2]

(ii)

Component B

[2]

(iii)

Component C

[2]

(iv)

Component D

[2]

(v)

Component E

[2]

How did you do?

1c

2 marks

Explain how X-rays are produced at the metal target.

How did you do?

1d

4 marks

The accelerating potential difference between the cathode and the anode of an X-ray tube is 75 kV.

(i)

State the maximum energy, in eV, of the photons produced in the X-ray tube.

[1]

(ii)

Calculate the minimum wavelength of photons in the X-ray beam.

[3]

How did you do?

Did this page help you?

1a

3 marks

The data in Table 1.1 shows how the attenuation coefficient μ depends on the energy of the X-rays in bone and muscle.

Table 1.1

maximum X-ray energy / keV	$μ_{b o n e}$ / cm⁻¹	$μ_{m u s c l e}$ / cm⁻¹
50	3.32	0.54
100	0.60	0.21
250	0.32	0.16
4000	0.087	0.049

Using the data in Table 1.1, state and explain which X-ray energy would produce an image of a bone next to a muscle with the best contrast.

How did you do?

1b

6 marks

For X-ray energies around 30 keV and below, the attenuation coefficient μ is approximately proportional to the cube of the proton number Z of the absorbing material.

The proton numbers of muscle, bone and some contract media are shown in Table 1.2

Table 1.2

substance	main elements
muscle	${}_{1}H$ , ${}_{6}C$ , ${}_{8}O$
bone	${}_{1}H$ , ${}_{6}C$ , ${}_{8}O$ , ${}_{15}P$ , ${}_{20}{Ca}$
contrast media	${}_{53}I$ , ${}_{56}{Ba}$

Using the information in Table 1.2

(i)

Show that bone absorbs X-rays about eight times more strongly than muscle.

[3]

(ii)

Explain why contrast media are made from elements with high values of atomic number Z.

[3]

How did you do?

1c

4 marks

The graph in Fig. 1.1 shows how the attenuation coefficient μ of muscle varies with photon energy E.

24-1-2c-h-24-1-h-attenuation-xray-energy-cie-ial-sq

Fig. 1.1

Using Fig. 1.1, explain why X-rays with energies less than 20 keV are usually filtered out of the beam.

How did you do?

1d

3 marks

An X-ray beam of energy 20 keV and intensity $I_{0}$ is incident on a sample of muscle and bone as shown in Fig. 1.2. The emergent beam intensities from the muscle and bone are $I_{m}$ and $I_{b}$ respectively.

24-1-2d-h-24-1-h-muscle-bone-xray-comparison-cie-ial-sq

Fig. 1.2

Using the graph in Fig. 1.1, calculate the ratio of intensities to compare the attenuation produced by 1 cm of bone and 1 cm of muscle.

How did you do?

Did this page help you?

2a

6 marks

An ultrasound investigation was used to identify a small volume of an unknown substance in a patient. It is suspected that this substance is either a cyst or a tumour.

During the ultrasound investigation, an ultrasound pulse of frequency 5 MHz is passed through soft tissue and then into the small volume of the unknown substance.

The ratio of the reflected intensity to the incident intensity for the ultrasound pulse reflected at the boundary was found to be 7.54 × 10⁻⁵.

Table 1.1 shows some information about the density and speed of ultrasound in soft tissue, cysts and tumours.

Table 1.1

material	density / kg m⁻³	ultrasound velocity / m s⁻¹
soft tissue	1065	1530
cyst	1020	1570
tumour	990	1565

(i)

Use the information in Table 1.1 to show that the unknown medium is a cyst.

[4]

(ii)

A pulse of ultrasound reflected from the front surface of the cyst was detected 27.5 µs later and a pulse from the rear surface was detected 43.2 µs later.

Determine the length of the cyst, in cm.

[2]

How did you do?

2b

3 marks

Fig. 1.1 shows a beam of X-rays of energy 20 keV incident normally on some soft tissue which contains the cyst.

The cyst is located 2.1 cm from the surface of the soft tissue.

24-1-3b-h-24-1-h-x-ray-intensity-cyst-cie-ial-sq

Fig. 1.1 (not to scale)

The attenuation constant of the soft tissue is 0.85 cm^–1. The incident intensity of the beam is 4.6 × 10³ W m^–2.

The X-ray beam is switched on for a time t.

Determine the energy of the X-ray beam incident on the front surface of the cyst each second. State any assumptions you make.

How did you do?

2c

5 marks

The ratio of the intensities of the emergent X-ray beams X and Y is determined to be

$\frac{I_{Y}}{I_{X}} = 0.94$

(i)

Determine the attenuation coefficient of the cyst.

[3]

(ii)

Compare the quality of the images that would be obtained from the ultrasound and the X-ray scans of the cyst.

[2]

How did you do?

2d

3 marks

Suggest a different imaging technique that could be used to image the cyst. Explain one advantage and one disadvantage of using this technique over ultrasound.

How did you do?

Did this page help you?

1

3 marks

(i)

State what is meant by contrast in an X-ray image.

[1]

(ii)

A parallel beam of X-ray radiation is incident, separately, on samples of bone and of muscle.

Data for the thickness x of the samples of bone and of muscle, together with the linear attenuation coefficients μ of the radiation in bone and in muscle, are given in Table 10.1.

Table 10.1

	x / cm	μ / cm^–1
bone	1.5	2.9
muscle	4.0	0.95

Calculate the ratio

$\frac{intensity of radiation transmitted through the bone}{intensity of radiation transmitted through the muscle}$ .

ratio = ........................................ [2]

How did you do?

Did this page help you?

	Download	View
Easy
Medium
Hard

Type of scan
X-ray Imaging
Ultrasound
PET scan
CT scan

	μ / cm⁻¹
blood	0.23
muscle	0.22

Production & Use of X-rays (CIE A Level Physics)

Topic Questions