A remote thermal camera receives infrared radiation from warm machinery. A normal visible-light camera is also used, but it cannot make an image in a completely dark room without illumination.
.1
Explain why the two cameras differ in darkness and why the thermal image does not measure visible colour.
[3 marks]
.2
The infrared wavelength is 1.0×10−5 m. Calculate its frequency using 3.0×108 m/s.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A vibrating string is observed with a ruler in its plane. Its equilibrium position is at 12.0 cm on the ruler. The highest and lowest positions are 14.4 cm and 9.6 cm.
.1
Calculate the amplitude in metres.
[2 marks]
.2
A pupil says that increasing amplitude necessarily increases frequency. Evaluate the claim.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
An atom absorbs electromagnetic radiation and one electron moves to a higher energy level. Later the electron returns to its original level.
Explain the energy transfers and why the element does not change.
[4 marks]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
In a collision test the total momentum before impact is 0.500 kg m/s. Three repeats give total momentum after impact of 0.492, 0.501 and 0.495 kg m/s, all in the original direction.
.1
Calculate the mean total momentum after impact.
[2 marks]
.2
The uncertainty in the mean is estimated as 0.010 kg m/s. Evaluate whether these results contradict conservation of momentum.
[3 marks]
6 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A detector registers 96 counts per minute of background radiation. With a source present it registers 896 counts per minute initially and 496 counts per minute after 12 minutes.
.1
Calculate the initial corrected detected count rate in min−1 (counts per minute).
[2 marks]
.2
Determine the half-life in minutes.
[2 marks]
.3
Explain why the background must be subtracted before comparing the rates.
