## ACCELERATING EDUCATION

Physics keeps life going-物理 依据 生命

## Τρίτη, 18 Οκτωβρίου 2011

### Refraction of waves

The diagram below shows plane wavefronts incident on a boundary between two media

A and B.

The ratio

refractive index of medium B/ refractive index of medium A           is 1.4.

The angle between an incident wavefront and the normal to the boundary is 50

.
(ii) On the diagram above, construct three wavefronts to show the refraction of the

wave at the boundary.

(i) Calculate the angle between a refracted wavefront and the normal to the boundary.

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### IB TRAVELING WAVES

Graph 1 below shows the variation with time t of the displacement d of a travelling

(progressive) wave. Graph 2 shows the variation with distance x along the same wave of

its displacement d.

Use the graphs to determine the amplitude, wavelength, frequency and speed of

the wave.

Amplitude: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wavelength: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Frequency: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Speed: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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## Δευτέρα, 17 Οκτωβρίου 2011

### IB WAVES

A travelling wave is created on a string. The graph below shows the variation with time t of the

displacement y of a particular point on the string.

The variation with distance x of the displacement y of the string at t =0 is shown below.

(a) Use information from the graphs to calculate, for this wave,

(i) the wavelength.

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(ii) the frequency.

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(iii) the speed of the wave.

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EXERSICES

## Τετάρτη, 12 Οκτωβρίου 2011

### ΤΗΕ SUN

What is happening at the surface of the sun?