Wallace Hall Academy Physics Department NATIONAL 5 PHYSICS. Waves and Radiation. Exam Questions

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1 Wallace Hall Academy Physics Department NATIONAL 5 PHYSICS Waves and Radiation Exam Questions

2 WAVE PARAMETERS AND BEHAVIOUR B FM waveband has short(er) wavelength () First mark for describing FM as These radio waves do not diffract around hills () short(er) wavelength/higher frequency Second mark for indicating that short wavelength/higher frequency waves do not diffract as much. Answer can be given in the context of A and B. Do not accept: Waves bend These are independent marks. Candidates can still achieve () mark for correct description of long wavelengths/low frequencies diffracting. Answer can be given in the context of A and B. (a) 500 m s - () (0) must show correct unit v = d/t () 500 = 5/t () t = s () (c) (ii) Total time = x = 0.04 s () Sig fig range 0.0, 0.0, Must use value for speed from correct value for speed of sound waves in water Multiplication by can happen at any stage *check significant figures Check calculations to see if candidate has doubled distance at start or double time at end. This could have an impact on significant figure issues. Watch intermediate rounding issues (eg pupil may round to 0.0s x = 0.04s) this is acceptable Time interval is unchanged Any indication that changing the frequency has no effect on the time Speed (of sound in water) is same/unchanged. Frequency has no effect (on the time taken for the wave to travel the 50m) 4 V = f () 500= 5 x 0 6 x () = m () 5 C 6 (a) v = f λ () f = x 0 8 / 0.06 () = Hz () (ii) T = /f () T = /5 x 0 9 () = 0-0 s () Signals received at same time () Radio waves and microwaves have same speed () 7 (a) Energy () d = vt ().5 x 0 = x 0 8 x t () t = 500 s () 8 A () 9 B () sig. fig. range m, m m, m

3 0 (a) x 0 8 ms - Unit required λ = v/f () significant figure range: = x 0 8 /900 x 0 6 () (c) = 0.6m () t = d/v = / x 0 8 =0.4 s (a) Surface waves Longer wavelength accept:bigger/larger/greater/higher/ large/high not: wider, any answer based on frequency (c) The radio waves are reflected by the ionosphere accept: reflection, (total internal) reflection do not accept: bounce (off ionosphere), refraction (d) mention of satellite () + any valid function of satellite () signals transmitted back to Earth signals amplified/focussed signal frequency altered t = d/v () = 6.8/40 () () for data selection of 40 ms - = 0.0 s () 4 (a) 500 ms - () d = v t () = () = 540 (m) () So depth = 540 = 70 m () 4 4 (a) (a) (ii) (ii) Q () Q () v = f λ () 40 = 0 λ () λ = 0 7 m () d = v t () 0.4 = 40 t () t = 0 06 s () (c) Wavelength decreased () Speed of sound slower () 5 (a) v = d/t () 4 40 = d/ 0 () d = 0 68 m () d = 0 4 m one way () f = /T () f = /0.5 () f = 8 Hz () If correct speed (500) is used in (c) but is incorrect, can still get full marks. Note: mark is allocated for division by two: the division of time or distance by two can occur at any point

4 THE ELECTROMAGNETIC SPECTRUM Phototransistor/photodiode/CCD () NOT thermometer/thermopile/ thermogram - not suitable for given context NOT Infra red camera Infra red detector (a) P = X-rays Q = Ultra violet/uv (Black bulb) thermometer photodiode phototransistor () B () 4 A () 5 (a) Radio (signals/waves) have a longer wavelength than television (signals/waves) () Longer wavelengths diffract more () 0 8 ms - () ms - 6 C () 7 (a) Infrared () both arrive at the same time () both travel at the same speed (or speed of light or 0 8 m/s) () 8 B () Accept: thermofilm thermistor thermopile thermocouple thermographic film heat sensitive paper IR film CCD Do not accept: skin IR camera photographic film thermogram Must mention both points for full marks If radio diffracts more than TV signals only then () max. Must have correct value and unit NOT: same as speed of light alone

5 LIGHT E C (a) Greater Accept bigger, larger, longer but not higher Correct drawing and change of direction Arrows not required. (ii) All labels correctly shown 4 B () 5 C () 6 (a) 59 o () 40 o () 7 (a) Total internal reflection () Any angle less than 45 o () Angle of incidence must be more than critical angle () 8 C () 9 E () 0 (a) First mark only available if explanation attempted Ray must obey the law of reflection () Appropriate number of reflections () line not straight (-) (total internal) reflection (TIR) ()

6 NUCLEAR RADIATION (a) A Diagram (represents ionized atom) B An electron has been removed (from the atom) For this mark must explain that: Electron has been removed Fewer electrons than protons (ii) Alpha (accept symbol α) Accept: Wash hands Do not eat Wear protective clothing Use shielding Return to container as soon as demo is finished Or other suitable alternative Use forceps/don t point at eyes/wear gloves etc (c) Instrument sterilisation/treatment of cancer (ii) Beta (radiation) (accept symbol β) C D 4 A 5 (a) The radiation detector would detect a higher level of radiation count rate would be higher where there was a crack in the aircraft Time taken for the (radio) activity (of a radioactive source) to reduce by half. (ii) Source Y () gamma can penetrate through the metal aircraft () Long half life (). (c) Point away from face / people use tongs/ forceps Use lead (lined) aprons/gloves etc. (d) 48/ = 4 ( half lives) () (MBq) () for halving () for final answer Some indication that there would be an increase in the reading on the detector. Do not accept: Time for radiation/count rate to half. Y only acceptable answer. Additional () marks can only be obtained if Y is selected. Accept: Wash hands Do not eat Wear protective clothing Goggles Film badge to monitor exposure Limit exposure time Increased distance from source. Return to container as soon as demo is finished Or any other sensible alternative NOT: Film badge on its own wear gloves or gloves alone Unit not required but deduct () if wrong unit given in final answer Halving process () mark is independent of the calculation of the number of half lives.

7 6 (a) Any two correct count rate values from the graph, i.e. second = half of the first. () Half-life = hours () Any two valid answers. x () Weapons, atmosphere, rocks etc must be qualified in terms of radioactivity. (c) A type of electromagnetic radiation / wave/ ray Don t accept EM 7 A = N () If time not/wrongly converted max () t = 4,000 () (5 x 60) = 80 Bq () 8 C 9 E 0 E Time (hr) Activity MBq halving () halving activity times () Accept other methods if correct Answer not made clear ( ) Answer = 40 MBq () (a) Fission Accept induced fission Chain reaction 0 marks Must be spelt correctly P (slow) neutron Q (fissionable) nucleus R (fast) neutron S fission fragment/daughter product C 4 A 5 E 6 C 7 C 8 E 9 A 0 (a) A particle containing two protons and two neutrons A helium nucleus () The gain/loss of electrons by an atom () (c) Smaller nucleus (d) A = N/t () N = () = 44,000 (decays) () (e) Source may also emit β and/or γ radiation (accept other valid non-standard answer eg neutrons, positrons) ()

8 Must have correct value and unit VARIOUS (a) 0 8 m s - (ii) m s - marks ( or 0) NOT: same as speed of light alone (ii) d = v t () Must use value for speed from (a) = x 0 8 x 0.68 () correct value for speed of radio = m () signals If v = 40, then d = m Must use value for speed from (a) correct value for speed of radio signals Sig. fig range: 0, 0 4, 0 4, 0 49 (a) x 0 8 m s m s - If v = 40, then = 6 0-7m () (0) must show correct unit Do not accept: The speed of light Must use value for speed from (a) correct value for speed of microwave signals deduct for wrong/missing unit () If v = 40, then λ = m

National 5 Physics. Relevant Past Paper Questions from SQA Standard Grade Credit and Intermediate 2 papers. Unit 2: Waves and Radiation.

National 5 Physics. Relevant Past Paper Questions from SQA Standard Grade Credit and Intermediate 2 papers. Unit 2: Waves and Radiation. National 5 Physics Relevant Past Paper Questions from SQA Standard Grade Credit and Intermediate 2 papers Unit 2: Waves and Radiation March 2014 Transforming lives through learning N5 Physics Past Paper