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.
[2 marks]
6 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
At fixed potential difference 3.0 V, a thermistor carries 0.0020 A in cool water and 0.0060 A in warm water. It is the type whose resistance falls as temperature rises.
.1
Calculate the resistance in cool water.
[2 marks]
.2
Calculate the resistance in warm water.
[2 marks]
.3
A pupil says the current tripled because the supply voltage tripled. Evaluate the statement using the data.
[2 marks]
5 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A rock has mass 0.54 kg and volume 200 cm³. A pupil writes its density as 0.0027 kg/m³.
.1
Calculate the correct density in kg/m³.
[3 marks]
.2
Explain why the pupil's numerical division is not sufficient to justify the stated unit.
[2 marks]
7 marksHigher
Spec and skills
Original practice question
Answer and supported method checks
A spring stores 0.72 J when compressed by 0.060 m. It obeys Hooke's law throughout this compression. It launches an initially stationary 0.090 kg toy horizontally; 25% of the stored energy is dissipated.
.1
Calculate the spring constant.
[2 marks]
.2
Calculate the toy's speed when it leaves the spring.
[3 marks]
.3
Explain why the speed cannot be found by treating the dissipated energy as destroyed.
[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.
