Yr 12 2.7 Int Nature Q 03

Name: ______________________________

New Zealand Institute of Physics

PHYSICS Level 2

2.7 Demonstrate understanding of the integrated nature of physics Credits: Two

Answer ALL the questions in the spaces provided. If you need more space for any answer, use the pages provided at the back of this booklet and clearly number the question. For all numerical answers, full working should be shown and the answer should be rounded to the correct number of significant figures and given with an SI unit. For all ‘describe’ or ‘explain’ questions, the answer should be in complete sentences with all logic fully explained. Formulae that you may find useful are given on the next page.

For Assessor’s use only

Achievement Criteria

Achievement

Achievement with Merit

Achievement With Excellence

Identify or describe aspects of phenomena, concepts or principles.

Give descriptions or explanations in terms of phenomena, concepts, principles and/or relationships.

Give concise explanations that show clear understanding, in terms of phenomena, concepts, principles and/or relationships.

Solve straightforward problems.

Solve problems.

Solve complex problems.

Overall Level of Performance (all criteria within a column are met)

Physics 2.7 Question and Answer Booklet

Physics 2.7 Question and Answer Booklet

You may find the following formulae useful: 1 1 1 = + f do di

n1 v 2 λ 2 = = n2 v 1 λ 1 v=

Δd Δt

Fc =

v2 r

mv r

2

E p = 12 k x2 W = Fd Δ E p = Eqd

P=

di hi = do ho

ΔE t

n1 sin θ1 = n 2 sin θ2

v = fλ

d =

f =

1 T

∆v ∆t

v f =v i +at

v i +vf t 2

v f = v i + 2ad

a=

d = v i t + 12 a t2 ac =

m=

2

2

F = ma

τ=Fd

p = mv

Δ p = FΔ t

Ek = 12 m v2

Δ E p = mgΔ h

P =

W t

I=

q t

V d

F = Eq

ΔE q

V =IR

E= V=

P =IV

RT = R1 +R 2 + ...

1 1 1 = + + ... RT R1 R2

F =Bqv

V =BvL

F = - kx

F =BIL (sin θ )

Physics 2.7 Question and Answer Booklet

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You are advised to spend 40 minutes answering the questions in this booklet. QUESTION ONE: CALLING “CQ” – Part One Amateur radio operators are licensed by the government to operate radio communication equipment for personal use. In your study of physics you have already learned a lot of the physics required for an amateur radio licence. Radio waves are a type of electromagnetic radiation, and travel at the speed of light, 3.0 x 108 ms-1. One of the frequencies used by Amateur Radio operators is 7.1 x 106 Hertz. (a)

Calculate the period of this radio wave. _________________________________________________________________ _________________________________________________________________ period = __________________________________

(b)

Calculate the wavelength of this radio wave. _________________________________________________________________ _________________________________________________________________ wavelength = __________________________________

(c)

Name two other types of electromagnetic waves. _________________________________________________________________

Some New Zealand radio operators communicate to people in Canada by reflecting radio signals off the Moon. A radio signal transmitted from Earth reflects off the Moon and returns to the Earth 2.56 seconds later. (d)

Calculate the distance from the Earth to the Moon. Give the correct number of significant figures with your answer. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ distance = __________________________________

Physics 2.7 Question and Answer Booklet

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QUESTION TWO: CALLING “CQ” – Part Two Long distance radio communication is possible because certain radio waves undergo refraction as they pass into the ionised layers of the Earth’s upper atmosphere. The diagram illustrates the situation.

The ionised layer has a refractive index of 0.90 and the lower atmosphere has a refractive index of 1.0. Assume that the interface between the lower atmosphere and the ionised layer behaves as a plane boundary causing refraction. (a)

Describe the meaning of the term refraction. _________________________________________________________________ _________________________________________________________________

(b)

A radio wave of wavelength 20.0 m travels through the lower atmosphere and refracts into the ionised layer, calculate its wavelength within the ionised layer. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ wavelength = __________________________________

Physics 2.7 Question and Answer Booklet

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(c)

Explain what happens to the frequency of the radio waves in the ionised layer compared to their frequency in the lower atmosphere. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________

(d)

Will the radio waves refract towards the normal or away from the normal? Explain. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________

(e)

Calculate the angle of incidence required to produce total internal reflection. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ angle of incidence = __________________________________

(f)

Explain how the presence of the ionised layer allows radio signals to be received at a great distance away from the transmitter. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________

Physics 2.7 Question and Answer Booklet

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QUESTION THREE: CALLING “CQ” – Part Three Another way of achieving long distance radio communication is to broadcast a radio signal to a geostationary satellite, which then retransmits the radio signals to stations on Earth. A geostationary satellite is one that orbits the Earth in 24 hours. Geostationary satellites are placed in orbit at a distance of 35,600 kilometres from the surface of the Earth. The radius of the Earth is 6400 kilometres. The circumference of a circle = 2π r. (a)

Calculate the time taken in seconds for the satellite to orbit the Earth. _________________________________________________________________ _________________________________________________________________ time = __________________________________

(b)

Calculate the speed of a geostationary satellite. _________________________________________________________________ _________________________________________________________________ speed = __________________________________

(c)

Calculate the centripetal force exerted on a 42 kilogram geostationary. _________________________________________________________________ _________________________________________________________________ force = __________________________________

(d)

On the diagram below, use labelled vectors to show velocity, acceleration and force for the orbiting satellite.

Physics 2.7 Question and Answer Booklet

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Other satellites orbit at much lower altitudes (only a few hundred kilometres above the Earth) and complete an orbit of the Earth in less than two hours. (e)

Explain why geostationary satellites are preferable to low orbiting satellites for long distance radio communications _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________

Physics 2.7 Question and Answer Booklet

Assessor’s use only

Question Number

If you need more space for any answer, continue here. Clearly number the question. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________

Physics 2.7 Question and Answer Booklet

Physics 2.7 Question and Answer Booklet