An electric kettle has an input power of 2000 W. The useful power output, heating the water, is 1800 W.
.1
Calculate the efficiency of the kettle.
[2 marks]
.2
Calculate the power wasted by the kettle.
[1 mark]
.3
Give one way energy is wasted by the kettle.
[1 mark]
7 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
A current of 0.25 A flows through a 47 Ω resistor.
.1
Calculate the power transferred in the resistor.
Give your answer to 2 significant figures.
[3 marks]
.2
The p.d. across the resistor is 11.75 V. In one minute, 15 C of charge flows through it.
Calculate the energy transferred in one minute.
[2 marks]
.3
Show that your answers to parts 1 and 2 agree, and explain why.
[2 marks]
4 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Radium-226 decays by emitting an alpha particle:
88226Ra→ZARn+24He
.1
Determine the mass number A of the radon nucleus.
[1 mark]
.2
Determine the atomic number Z of the radon nucleus.
[1 mark]
.3
Strontium-90 decays by beta emission. Describe what happens in the nucleus during beta decay.
[2 marks]
7 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Waves travel across a pond. A floating leaf moves up and down 5 times in 2.0 s. The distance between neighbouring crests is 0.40 m.
.1
Calculate the frequency of the waves.
[1 mark]
.2
Calculate the speed of the waves.
[2 marks]
.3
Calculate the period of the waves.
[2 marks]
.4
The leaf moves up and down but does not travel across the pond with the waves.
Explain what this shows about the waves.
[2 marks]
8 marksFoundation and Higher
Spec and skills
Original practice question
Answer and supported method checks
Hospitals use X-rays to form images of the inside of the body. A CT scan uses X-rays from many directions. The table shows some typical radiation doses.
Typical radiation dose in millisieverts: one chest X-ray 0.02; one CT scan of the chest 7.0; background radiation in one year, UK average, 2.7.
Source of radiation
Typical dose in mSv
One chest X-ray
0.02
One CT scan of the chest
7.0
Background radiation in one year (UK average)
2.7
.1
Calculate how many chest X-rays give the same dose as one CT scan of the chest.
[2 marks]
.2
Calculate the dose from one CT scan of the chest as a percentage of the yearly background dose.
[2 marks]
.3
A patient has had a cough for several months. Evaluate the use of a CT scan of the chest to find the cause.
[3 marks]
.4
Give one harmful effect of ultraviolet radiation on the human body.
