Read the information below about a hospital treatment unit. A newborn baby has jaundice and is placed under a special blue-light lamp. The light helps break...
Question 1 Report
Read the information below about a hospital treatment unit. A newborn baby has jaundice and is placed under a special blue-light lamp. The light helps break down a substance in the baby's blood. The unit has a transparent cover, a timer and a warning sign. A nurse checks that the lamp is not an ultraviolet source before treatment. The lamp transfers 18 kJ of energy as light during a 20 minute treatment.
(a) State the region of the electromagnetic spectrum used by the treatment lamp. [1]
(b) Explain why ultraviolet radiation would not be suitable as a replacement for the blue lamp. [3]
(c) Calculate the average power output of the lamp during the treatment. [4]
(d) Describe why the transparent cover must allow visible light to pass through it. [2]
(e) State two variables, other than lamp power, that the nurse should keep the same when comparing two treatment lamps. [2]
(f) Explain why a timer is included in the treatment unit. [2]
(g) Which type of electromagnetic wave could a nurse use to measure the baby's skin temperature without touching the skin? [1]
(h) Explain why this temperature measurement can be useful during treatment. [1]
Answer Details
(a) Blue light is in the visible-light region of the electromagnetic spectrum. [1]
(b) Ultraviolet has higher frequency and more energy than visible light. [1] It can damage skin cells or DNA. [1] This may cause sunburn or increase cancer risk, so it is not a safe replacement for the visible blue lamp. [1]
(c) Convert both quantities to SI units:
\[18\text{ kJ}=18\,000\text{ J}\] [1]
\[20\text{ min}=1200\text{ s}\] [1]
\[P=\frac{E}{t}\] [1]
\[P=\frac{18\,000\text{ J}}{1200\text{ s}}=15\text{ W}\]
The average power is 15 W. [1]
(d) The treatment light must reach the baby. [1] If the cover absorbs or reflects visible light, less useful radiation reaches the skin. [1]
(e) Keep the distance between lamp and baby the same [1] and keep treatment time the same. [1] Exposed skin area, cover type or thickness, and baby's position are also acceptable controls.
(f) The timer controls exposure time and hence the dose of light. [1] It prevents too little treatment or unnecessary prolonged exposure. [1]
(g) Infrared radiation can measure skin temperature without touching the baby. [1]
(h) It allows temperature to be monitored without touching or disturbing the baby. [1]
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