Fig. 1 shows a dental radiography room. A dentist uses a machine to produce an image of a patient's tooth. A detector is placed inside the patient's mouth a...
Question 1 Report
Fig. 1 shows a dental radiography room. A dentist uses a machine to produce an image of a patient's tooth. A detector is placed inside the patient's mouth and a beam passes through the tooth. The dentist leaves the room before the exposure is made. The wavelength of the radiation used is 0.20 nm.
(a) State the name of the electromagnetic radiation produced by the machine. [1]
(b) Explain why the detector can show an image of the tooth. [3]
(c) State two precautions that reduce the risk from this radiation. [2]
(d) Calculate the frequency of radiation with a wavelength of 0.20 nm.
Use a wave speed of 3.0 × 108 m/s. [3]
Answer Details
(a) The machine produces X-rays. [1]
(b) Different materials absorb different amounts of X-rays. [1] Tooth and bone absorb more X-rays than soft tissue. [1] Different amounts therefore reach the detector, producing contrast and an image of the tooth. [1]
(c) Two suitable precautions are: the dentist leaves the room or uses a protective screen, and the patient wears a lead apron. Keeping exposure time short and taking only necessary images are also acceptable. [2]
(d) \[0.20\text{ nm}=0.20\times10^{-9}\text{ m}\] [1]
\[f=\frac{c}{\lambda}=\frac{3.0\times10^8\text{ m/s}}{0.20\times10^{-9}\text{ m}}\] [1]
\[f=1.5\times10^{18}\text{ Hz}\]
The frequency is \(1.5\times10^{18}\text{ Hz}\). [1]
Download The App On Google Playstore
Everything you need to excel in your exams
